SF Bay Area Koi Club

Organization of Pond and Koi Keepers

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  • 07/10/2021 7:14 PM | Anonymous member (Administrator)

    They won’t wipe out insects completely, but their unique properties may send pests in another direction.

    By Korin Miller

    Jun 28, 2020

    close up of purple flowering plants on field

    When it comes to the inevitable face-off between you and bugs, keeping them away from your immediate vicinity is probably top priority as they thrive during the warmer months. While there are always options like pesticides and bug traps, it certainly doesn’t hurt to explore potential natural solutions before trying harsher chemicals (even though they can be necessary with serious infestations).

    That’s where plants come in. There are a slew of different herbs, bushes, and flowers you can put in your garden or outdoor space that have a solid reputation for keeping bugs away. “Plants are in the business of repelling insects, because this is one of the most important ways to avoid insect damage—by feeding,” explains entomologist Roberto M. Pereira, Ph.D., an insect research scientist with the University of Florida. But, of course, plants also need insects to perform cross-pollination so they can survive. “It is an arms race between plants and insects, each trying to survive and prosper,” Pereira says.

    Not sure where to start? Below, we rounded up the plants gardeners love to use to repel annoying bugs. They won’t wipe out mosquitoes, ticks, or flies for good—no plant really will—but their unique properties may send pests in another direction while simultaneously sprucing up your yard, garden space, or patio.

    Citronella grass

    citronella plant


    You’re probably most familiar with citronella candles to repel mosquitoes, but the smell comes from a plant called Cymbopogon nardus, which gives off a distinct beach grass vibe. It’s the oil from the plant that’s actually the repellent, according to the National Pesticide Information Center (NPIC).

    But Pereira says you’d need to have a lot of them to mimic the concentrated effects of burning a citronella candle or torch, so you shouldn’t rely on plants alone to keep mosquitoes away.

    If you just want one citronella plant, though, consider placing it in a pot near an outdoor seating area. “This plant gives off very little aroma—you can smell it if you crush the leaves—and so would only work if you were sitting right up close to it,” says board-certified entomologist Nancy Troyano, Ph.D., director of operations education and training for Ehrlich Pest Control.


    lemon grass plant tree growing on the garden plantation for food and herb leaf


    Lemongrass is a tall, perennial grass that’s native to tropical and sub-tropical climates of Asia. It looks a lot like citronella grass, and also has similar mosquito-fighting properties, Pereira says.

    One scientific literature review found that lemongrass oil offered up to 95% protection against certain types of mosquitoes for 2.5 hours, while another study found the oil can deter stable flies in a lab setting. Keep in mind, though, that it was the oil that was studied—not the plant itself. But if you’d like to add a few to your yard to see if they help, it’s a great place to start.


    mint plant grow at vegetable garden


    Many commercial bug repellents contain plant essential oils, and peppermint oil (which comes from peppermint plants) is one of the most promising when it comes to warding off mosquitoes, research suggests, as well as certain spiders.

    But it’s not clear why, exactly, some bugs don’t love it, Pereira says, although the strong smell may have something to do with it. Again, studies have mainly been done on various mint oils, not the plants.

    Another hack to consider: You can combine 10 drops each of peppermint, thyme, and rosemary essential oils mixed with water in a spray bottle. Then, spritz the solution around your garden to help repel flies, fleas, mosquitoes, aphids, antsspiderschiggers, and more.




    Catnip is known for its ability to give your feline friends a mellow buzz, but the herb also has some bug repellent properties. One study found the essential oil from catnip can help deter houseflies and mosquitoes. Another study from Iowa State University also found catnip oil to be a more effective “spatial repellent” than DEET, the most popular ingredient in insect repellents. Same caveat, though: Catnip oil isn’t the same as actual catnip plants, but the results are promising enough to warrant adding a few to your yard if you don’t have cats to worry about.


    sage salvia herbal plant


    This herb has a reputation for getting rid of ants, flies, and mosquitoes, but there isn’t a ton of science to support the claims outside of mosquitoes. Research has found that having a pot of sage around can offer up to 32% protection against certain types of mosquitoes. Since that’s 32% more protection than you’d get with no repellent, it’s not a bad idea to consider sage in the future, especially if you enjoy adding fresh sprigs to your meals.


    purple petunia flowers in the garden


    These colorful annuals have the potential to keep away bugs like aphids, certain beetles, leafhoppers, and squash bugs. But, keep in mind that you need them to bloom to do their thing. Petunias’ potential bug-repellent properties “may only be there if flowers are present,” Pereira says.


    closeup of orange marigold flowers and foliage


    Marigolds contain pyrethrum, an insecticidal compound that’s used in bug repellents. There isn’t a ton of research on the effects of marigolds on insects, but gardeners have long sworn by them to keep annoying pests, like mosquitoes and destructive nematodes, at bay. These annuals, while gorgeously vibrant, have an off-putting smell that many bugs (and people!) don’t seem to like. Try using them to create a pretty border around your patio, or place potted marigolds near common entryways, like doors and windows. (Just keep arrangements away from tables, where they may attract bees and wasps!)


    green fresh rosemary spicy herb sprouts


    This spiky herb, thanks to its particularly pungent scent, may help keep mosquitoes away, Troyano says. In fact, research
    has found that, when compared to 11 other essential oils, rosemary had the longest repellent effects on mosquitoes, and may even deter other insects like aphids and spider mites—just note that these results were all based on rosemary oil.


    lavender field


    Research has found that lavender can be effective at repelling mosquitos and other arthropods. It’s not clear why the flowering plant can act as a repellent, though—it could just be that the smell doesn’t appeal to bugs, Pereira says. “What is pleasant to you does not have to be pleasant to other humans, other mammals, other vertebrates, or other animals including invertebrates such as mosquitoes,” he says.


    fresh basil herb in pot


    A study published in the Journal of Vector Ecology found that basil—specifically hairy basil—knocked down and killed certain types of mosquitoes 100% of the time. Here’s the thing: This was tested in essential oil form, which is likely to be more potent at fending off mosquitoes than the actual plant. Overall, though, Pereira says the plant “produces a repellent odor that mosquitos don't like.

  • 09/12/2020 12:08 PM | Anonymous member (Administrator)
    Complete Aeration Kits


    In order to have a healthy, beautiful pond, you need to make sure your pond is receiving enough oxygen. Aeration is the infusion of oxygen and it is essential component to the overall life of your pond. When pond water is stagnant, only the surface of the pond can oxygenate, leading the rest of the pond with a lack of oxygen and nutrients.

    Are layers of algae aggressively growing in your pond? Or are there distinct, foul odors being emitted from your pond? Do the fish in your pond come up to the surface gasping for air or simply won’t leave the area by a water feature? These are all signs that correlate with the issue of not having enough oxygen in your pond. Making sure that your pond is properly aerated is essential for the health and life of your pond. When pond water is stagnant, only the surface of the pond can oxygenate, leading the rest of the pond with a lack of oxygen and nutrients.

    Here are a few reasons why you should consider aeration for your pond:


      If there is not enough water circulation in your pond, then “muck” will form in the bottom of your pond. Muck is the build-up of different organics sometimes including plant waste, animal waste, dead algae, weeds, and grass. Aeration increases aerobic bacteria which helps fight build-up and will reduce the muck accumulated.


      A calm, still pond is the ideal environment for mosquito larvae to live. Aeration keeps the water circulating throughout the pond resulting in an inhabitable place for mosquitoes to lay their eggs.


      Proper circulation of the water helps stabilize Ph levels, reduce alkalinity, and remove excess carbon dioxide. These improvements will contribute in a reduction of algae and weeds all while improving the overall water quality and clarity of your pond.


      Much like us, fish rely on oxygen to live. If the supply of oxygen in your pond is not great enough, then your fish will not get the nutrients they need to survive. Without aeration, not only can your fish not receive the oxygen they need, but toxic gases will have no way to escape which will harm and kill the fish.

  • 07/24/2020 6:36 PM | Anonymous member (Administrator)

    Red Koi, blue Koi, upstream, downstream, what are Koi meanings in tattoos?

    If a tattoo is on your bucket list you might do a little research ahead of the permanent ink hitting your skin. Interestingly, Koi in tattoos represent many things, from the direction they are swimming, to the color of the Koi itself, and whether it is a standard fin or butterfly fin. Koi tattoo are some of the most intricate, colorful, and most common tattoo. Koi legends go back many, many years and symbolize heroism and sacred myths.

    Koi, in general,  represent good fortune and luck. In Chinese art, Koi bring luck, wealth, and a happy marriage. In a tattoo, Koi swimming upstream represent striving amidst diversity and challenge, a new beginning, or to fulfil destiny which symbolizes the legend of the Dragon Koi. As legend tells it, Koi swam up stream in the Yellow River against great currents and adversity. The bravest of these was able to leap the falls and the Gods' rewarded it's bravery by turning it into a magnificent Golden Dragon. Those falls are known as Dragon's Gate. A Koi swimming downstream represents someone who has already dealt with trials and adversity and is moving on. For some, it may also represent giving up on someone or something. A single Koi is eye catching and double Koi represents yin-yang, the dance of life and harmony. Two Koi can also represent the ability to go with the flow. A tattoo with lotus added symbolizes purity, rebirth, and a successful struggle. A cherry blossom symbolizes fertility/femininity. Fallen cherry blossoms represent a fallen warrior/samurai. 

    Colors also have specific symbolism attached to them. A full black Koi turning into a Dragon represents independence, unstoppable determination, courage, or life changes. The black Koi also symbolizes the father. The gold/yellow Koi symbolizes prosperity, good fortune, and treasure. The white Koi with a red marking on the head symbolizes career success. A white Koi with red lips symbolizes enduring love. A silver-gold platinum-colored Koi symbolizes business success. A red Koi symbolizes love, the mother of the family/power and bravery. Artificial Koi colors symbolize gender. A blue Koi symbolizes tranquility, masculinity, strength and the son. A pink Koi represents a delicate female and the daughter. 

    Koi have powerful symbolism whether in legends, ponds, or tattoos that date back to ancient times and, thus, have stood the test of time, no wonder we are intrigued with them in art, ponds, and tattoos. Will you be checking out a Koi tattoo the next time you see one to see if you recognize it's symbolism?

    by Brenda Bartz

  • 02/09/2020 6:52 AM | Anonymous member (Administrator)

    Spring Has Sprung?

    Not much goes on in an overwintering pond. With the water being less than 55 F, plants, fishes and invertebrates are largely in a "resting mode" metabolically, requiring no feeding. Pond gear, like pumps and filters may actually be turned off completely, particularly in regions where water may freeze. Deep ponds may be neglected entirely, whereas shallow ones might require your intervention to prevent freezing over (and down) completely. Maintenance activities are at a standstill as well. Wastes should have been removed during the latter Fall and new leaf litter et al. left for removal in the coming Spring. Fooling with very cold ponds can be disastrous, both to pond livestock and their care-keepers. Best by and large to do your planning, and leave the pond be during the coldest season'¦ if you have such in your setting.

    For those uninitiated with ponds and cold winters, do NOT fool with a fish-containing system covered with ice. The shock of even walking on the surface, let alone striking it, can easily kill your fishes.

    When Days Get Long/er:

    Changes in your pond are far more telling than a rising reading on a thermometer. Look to your plants and animals for signs of Spring and as with your terrestrial gardening, be prepared with a plan, tools and materials to meet the new season.

    Once frost is gone, marginal plants can be worked, thinned of dead growth. Fishes should be fed initially low-protein (less than twenty percent) diets once the water attains a daily temperature of 55 F. and they show sufficient interest in same.

    True aquatic plants and mucking about in, cleaning the pond basin/s should wait till the water is warmer'¦ for you and your livestock. A good minimum of sixty degrees Fahrenheit is about right. The stress of overwintering and your stirring about in the system is otherwise too much for "just defrosted" livestock.

    If your pump/s, filters and plumbing have been off during the cold weather, do make sure and "flush" them with water, voiding the initial water to waste, to prevent poisoning the system.

    Later On:

    As your fishes bulk up on regular feeding and your biological filtration is restored (if shut off as in colder regions for the season), heater/de-icing gear should be turned off/removed and thought given to a semi-thorough cleaning of your pond basin/s. Likely a good net-leaf removal will serve to eliminate the bulk of material that has accumulated over the Winter, but if you have a vacuum system, a careful partial removal over a period of days to weeks may be in order. Best to remember that "cleanliness is not sterility" in biological systems like ponds, therefore to go slowly in removing organic material and never remove all. Take care to treat replacement water with dechlorinator and make changes with water of about the same temperature.

    Should your water turn murky, or an unsightly algae bloom seem to "take over", don't panic'¦ Look to the root causes of these cycles. Warmer water, extended photoperiod, the release of bound-up nutrients and new chemical foods through your feeding. If your fish livestock is none the worse for these events, consider a slow approach to their solution. Not unlike turning a large ship with a small rudder, nothing good happens quickly in a biological pond. Slow and steady as she goes. As the Spring wears on, activities like re-potting and fertilizing plants, adding fishes and other animals can be engaged.

    Spring Pond Maintenance 

    Though the seasons are of a certainty cyclical, we mostly center on springtime as the "beginning" of years'¦ As a pond-keeper this IS the time of your greatest activity and concern. In the new year's warming months, all related gear is checked and re-instituted, livestock "wakes up" and is at its most vulnerable to damage, and we, ourselves venture out to enjoy, engage our water features and their inhabitants.

    Spring Sprung?

    A systematic approach to details of pond mechanicals and cleanliness will ensure you a trouble-free, enjoyable summer and fall with your water feature. Pond filters, plumbing, pump/s, controllers if any need to be checked, tested, and water vented through them if they've been shut down for the winter. Livestock will begin to stir as the water warms and should be examined as they begin to feed, for signs of parasitic infestation. If you've had a notion to initiate new algae control measures, now is the time to set them in motion'¦

    But before you start, do make sure that the cold weather time is past; by monitoring your ponds water temperature. Air temperature during the day or night is no valid indicator of what is going on in your system. Get and use (preferably a encased, non-breakable type with a string!) a good thermometer and record your water temperature for a good week or two after it approaches 50 F. during daytime. When in doubt whether time has come to start working on your pond, wait.

    Pumps/Plumbing/Filters & Basins:

    Once the chance of water freezing in your plumbing is past, and there is a definitive warming trend in the weather, one can give attention to inspecting, repairing and "firing over" pond pump/s and filters (if they haven't been running continuously of course, as in warm weather regions). Though the water may still be quite cold to you, once it nears and stays about 50 F. or higher during the days, it's time to prime the lines, turn on filter and recirculating pumps, test all valves and skimmers for function and turn all on. A cautionary note re the initial start-up: It is STRONGLY advised that the first few minutes of water coursing through your lines and filters be vented to waste, to prevent the pumping of polluted water into the system. Be forewarned that this water can be stinky!

    Basins, whether cementitious, fiberglass, polyethylene or liner in construction need to be checked for integrity'¦ as does any penetrating rock work, particularly that which may make up your waterfall/s. Cold weather, water/ice expansion can play havoc on the water tightness of basins and such during winter. Make sure your system doesn't leak before leaving the pumps running. Liners may crack, one-piece basins be uplifted, whole basins may require lowering the water to effect repairs.

    Clean-up Time:

    Along with general checking on the pond, its components and livestock is the issue of "spring cleaning", the removal of accumulated "gunk", leaves, soil, what have you, from the basins. This should not be attempted while the system is still cold, and a good indication of when it might be time is the relative temperature of your tap/source water. It's best to wait till these are about the same, as you will be re-filling the system with this water and it needs to be about the same temperature. Another concern is that you not be too fastidious in your cleaning. You do NOT want to totally dump, scrub, and remove all traces of detritus in your initial effort here. Very important instead to take your time in vacuuming, netting out a good portion (let's say up to 80-90 percent) of unwanted material, and no more than 20-25% of the water'¦ re-filling it slowly (as in a drip), with dechlorinator to prevent poisoning from tap water sanitizer.

    Check around the pond perimeter for movement of soil that should be removed to prevent it entering the pond. Check your drainage scheme to insure that it is clear of debris to preclude floodwater from entering the pond or water overfilled from the pond escaping to other areas.

    Established Livestock Concerns:

    Now is the time, while investigating the surrounding landscape, to devise your plan for scaling back seasonal overgrowth and making mental notes re what you intend to add during the growing season to embankments and nearby plant areas. Remove dead and left over excess growth of out of pond plants, fertilize them and/or augment soil as you see necessary, but hold off till the pond is a bit more re-established (let's say mid to late spring) to do much with the bog and truly aquatic plants. Once again, there is a need to "go slow" initially in doing much with changing water quality in the new year. In later spring, potted and interior border-grown plantings can be re-potted and fertilized as new growth becomes evident. A semi-last cautionary note here: be careful in getting in and out of your pond. These are treacherously slippery, and oh-so easy to slip and fall in.

    Fishes should be carefully examined for signs of disease. The spring is their parasite and infectious fauna's "hay day" and it's important to catch any latent or new problem here and now. You will find there are many, MANY disparate opinions on the how and what to treat symptoms, apparent pathogens with'¦ Whatever protocols you settle on I encourage you to administer medicants OUTSIDE your pond'¦ in a more controlled, easier observation container like a net-covered kiddie pool or large aquarium. Historically, attempts at treating livestock in their main ponds are expensive and disastrous. Most result in more damage than good.

    It's best to hold off on such treatments till the water is at least 60 F. These medications may take the form of liquid prep.s of formalin, malachite, copper'¦ or medicated foods, even injections. Take a look on the Internet AND established print sources of information on pond fish disease before embarking on any given regimen. If you can, hold off on handling, moving your fishes till the water is in the 60's F. Moving them before this time/temperature can be much more harmful than the effects of any given disease. 

    Plants can be divided, re-planted and fertilized once the water is steadily in the 50's F. or higher'¦ I like to wait (for my comfort) till the water is even warmer still, but as a general rule most plants should be so manipulated no later than mid to late spring. Use the appearance of new-growth to gauge when to start such work.

    A brief related note regarding the use of various test kits (pH, ammonia, nitrite, nitrate, phosphate et al.). There are times when folks seem to become mesmerized with testing. Such assays for water quality do indeed have their place, but I caution you to first and foremost rely on your powers of observation on examining your livestock. Few "things" happen quickly in ponds that are pleasant'¦ and you are cautioned to "when in doubt, leave it out", where questions arise as to take action or alter your waters make-up in the face of apparent good health in your fishes and plants.

    Acquiring and Placing New Livestock:

    Other than concerns re pest snails and possibly algae, you might think the introduction of new aquatic plant material holds little challenge in ongoing ponds. Such is not the case however and you should isolate new purchases for two weeks or so to weaken potential infectious bacteria and parasites, possibly immersing them in a prophylactic alum (aluminum sulphate) bath before allowing them to be placed in your pond. The standard operating procedure for alum baths is to mix a teaspoon of the solid in a quart of water, immerse the plants for about ten minutes, and then rinse them thoroughly. Most plants offered/utilized in ponds are of cool water origins, but you should wait on introducing non-hardy water lilies, water hyacinth and water lettuce till your water reaches the mid 60's F. consistently. <Pix, some hardy and tropical lilies'¦ most of the former are "warm colored", reds, yellows'¦ and have flowers whose petioles/stems lay flat at the waters surface. Tropicals are often "cool colored" and have stems that are immerse. And a pic of Pistia stratiotes, Water Lettuce>

    With fishes you are advised to utilize the same simple, effective quarantine method with all new purchases. The same "treatment" system of a covered holding tank, filtration/aeration can be employed here. All new fish purchases should be acclimated and maintained for a minimum of a two-week period to 1) give them time to "rest up", 2) grant you opportunities to observe them for possible pathogens, and 3) if necessary treat them for same. If you live in a cold (ice) to cooler weather region, you're encourage to hold off on acquiring new fish till later spring, when these animals immune systems are entirely functional.

    If you've kept your fishes, maybe even plants "indoors" in an aquarium or pool in the garage, patio over winter, do wait until time in which their current ambient water temperature matches the warming weather, water temperature of the pond to re-locate them outdoors. Thermal stress is a principal determinant of health/disease with this life, and adding to the negative side of the equation by too-early moving of livestock can be disastrous.

    About Algicides:

    Well-designed and maintained water features don't have serious "troubles" with excess algae, but all must need be watched/monitored to prevent outright algal "explosions". If you sense you have too much algal growth, you likely do'¦ and need to give thought to your best control methodology. Is it an excess of nutrients, too much available sunlight, a lack of competition for these same? Is your water chemistry out of whack? Is your waters pH too high or experiencing too much diurnal fluctuation? What do you feed (purposely and inadvertently through fertilization and water changes) into your system? When is the last time you thoroughly checked your filtration? Would improved circulation, aeration; even the addition of barley bales, an in-line ultraviolet sterilizer or purposeful beneficial bacteria improve your chances of controlling excess algae?

    A very reasonable and easy mechanism to reduce the likelihood of "green, murky water" in spring is to effect a series of partial water changes. After your water warms to 50 F. or higher, a portion (10-20 %) can be vented and slowly (as with a drip from a hose) refilled (with water conditioner added ahead of time). This change-out accomplishes several important benefits: diluting wastes accumulated during winter, reducing the amount of nutrients available to pest algae, flushing out pathogens, and infusing the system with oxygenated water. 

    Lastly on your list of "tools to combat algae" should be chemical algicides. Few of these are effective and none are truly safe to use. If you go the chemical route, do so with the knowledge of the actual gallonage of your system and carefully administer doses with an ever-present eye on its effect on your livestock. Be aware that most of these compounds have a very narrow range of efficacy. That is, there is not much "room for error" in their overdosing. Some that are Simazine based are toxic to surrounding terrestrial plants as well as aquatic. Use with extreme care.

    >Sidebar< Calculating Pond Volumes:

    There are a few mathematical formulae for estimating the size and hence the volume of a given pond (there are about 7.5 gallons of water in a cubic volume of one foot), but the best, most accurate method of approximating volume is to measure the rate of flow to filling a given known volume (like a five gallon "pickle" bucket) and measuring the time it takes to fill your pond'¦ multiplying the equivalent time by the time per known volume. An example: Let's say it takes twenty seconds to fill a five gallon bucket from your house, and some two and a half hours to fill your pond'¦ From the first experiment, your hose delivers about a gallon every four seconds'¦ and it took (2.5 hours times 60 minutes per hour, times 60 seconds per minute equals) 9,000 seconds'¦ so, 9,000 seconds of water, divided by 4 seconds per gallon, gives you 2,250 gallons of volume in your pond.

    About Feeding Your Fish:

    Breaking into and establishing a routine of offering food is tricky just after wintertime. First foods should be low-protein (less than 20%, check the bag label) and composed of little animal material (for ease of digestion). Feed sparingly'¦ only a few pellets or sticks, at first, and if the food is not accepted, remove it and add no more till the water is warmer. A general rule of thumb is to feed nothing at temperatures below 50-55 F., once a day between 55-65 F., twice a day between 65-75 F'¦ But be wary of the initial start-up of feeding. Koi and goldfishes will eat more than they can digest'¦ and simply ingesting food will do them more harm than good. Again, my advice, feed nothing until your water is at least 50 F. during the day. Oh, and higher-protein foods can be commenced once your water temperature is in the 60's F., initially mixed in with more easily digested lower-protein kind/s.



    With increasing temperatures of our planets solar cycling, come awareness and tasks for the earnest Pondkeeper. Make a list of activities, tools and materials; adapted; adopted from this article and "be prepared" for checking your system, its livestock and doing requisite clean up come spring. Be aware that as your livestock's metabolism "wakes-up" this is a very delicate time to adjustment, and that you should proceed with caution in adding to chemical, physical and/or biological changes. Wait till the water has warmed up, remains in the 50's F. before proceeding, and then not overtly. Fifty degrees Fahrenheit is indeed a "magical number", signifying about the time that's best to re-start pumps, initiate feeding of pond fish, re-pot and fertilize plants, and begin regular maintenance to your "new" pond.

  • 09/03/2019 6:41 PM | Anonymous member (Administrator)

    This synopsis is of a study that showed the benefits of Koi getting some sun near the surface.  Even fish sometimes need to catch some rays.

    Researchers recently conducted the first-ever investigation of sunbathing fish, to see if they were able to directly absorb heat from sunlight — as lizards, snakes and insects do — and to understand how that ability might benefit them.

    Previously, scientists thought that sunbathing fish couldn't warm up to temperatures higher than those of sun-heated water. But in the new study, researchers discovered that sun-seeking carp absorbed and retained more heat than surface water did, and that solar-heated fish grew faster than their chilly neighbors.

    Nearly all fish are ectotherms, or cold-blooded animals, which means that they warm their bodies by drawing heat from their environment. Only one type of fish — the opah, or moonfish — is known to generate its own heat, by vigorously waving its pectoral fins as it swims.

    When land-dwelling ectothermic animals — including lizards, snakes and frogs — need to warm up, they seek out a sunny spot and soak up the sunlight. But it was long thought that cold-blooded fish and other animals that live in water were denied this extra heat because of water's cooling effect.

    To test that hypothesis, scientists submerged physical models in water and measured their temperature after exposure to natural sunlight. They found that the models did become warmer than the water.

    Next, to see if the same thing would happen to living animals, they tagged 48 free-ranging carp (Cyprinus carpio) with sensors to monitor their body temperatures, and released them in an artificial clay pond. After observing fish that basked in the sun near the water's surface, the researchers discovered that the sun-worshipping fish became warmer than the water temperature by as much as 7.2 degrees Fahrenheit (4 degrees Celsius) — a feat that was previously thought to be impossible, according to the study.

    Temperament played into this behavior too, with bolder fish more likely to "sunbathe" than more timid swimmers. Individual coloration was also a factor, as darker carp absorbed more heat than paler fish.

    And basking carried benefits: Sun-warmed fish grew faster than fish that lurked in cooler depths, demonstrating the ecological and evolutionary importance of this previously unknown ability, lead author Oscar Nordahl, a doctoral candidate in the Department of Biology and Environmental Science at Linnaeus University in Sweden, said in a statement.

    Source: The findings were published online May 30, 2018 in the journal Proceedings of the Royal Society B

  • 05/26/2019 7:22 AM | Anonymous member (Administrator)

    This article is about size change in fish do to global warming, but has an excellent description of why larger Koi require more O2 than smaller Koi.

    Fishermen over the past several years have noted that fish appear to be shrinking. That observation was validated in 2014 by research that found commercially important fish stocks in the North Sea, such as sole, herring, and haddock, have decreased in maximum body size over a 40-year period. Scientists suspected that climate change was the culprit, but were unsure how warming waters could lead to fish shrinkage across entire species.

    New research published in the journal Global Change Biology describes the mechanism that is likely causing fish to shrink. Lead author Daniel Pauly, a principal investigator with the Sea Around Us project at the University of British Columbia, said the findings apply to animals with gills, such as fish, sharks, squid, and lobsters.

    Pauly's co-author William Cheung, director of science for the Nippon Foundation Nereus Program at the university, explained that these species and many others are ectotherms, meaning that their body temperature depends on environmental temperature.

    "As the oceans warm up," Cheung said, "their bodies will do so as well. Higher temperature within the scope that the fish can tolerate generally increases the rate of biochemical reactions in the fish's body and thus increases their body metabolic rate."

    Metabolic rate refers to an animal's oxygen consumption, which also naturally increases as fish grow into adulthood because their body mass becomes larger.

    One might wonder why fish and other marine ectotherms aren't just taking in ever more oxygen to coincide with this natural growth due to maturation and the rise of ocean temperatures. They don't because at a certain point they cannot keep up.

    The researchers point out that the surface area of an animal's gills — where oxygen is obtained — does not grow at the same pace as the rest of its body.

    "This is because gills, in order to work, must function as a two-dimensional surface — width by height — and thus cannot grow as fast as the three-dimensional volume — width by height by depth — they have to supply with oxygen," Pauly said.

    He and Cheung liken how a fish gill works to a car radiator. Both are made up of numerous thin layers that allow for the transfer of heat, which permits cooling. But both can only work in two dimensions because air or water pass through only once.

    "There is not much that fish can do to solve this problem," Pauly said. "They can have bigger gills — just as sports cars have bigger radiators — but ultimately, the weight always catches up, and the ratio of gill surface to body weight becomes too low."

    The researchers believe this set of principles, which they have named the Gill-Oxygen Limitation Theory helps to explain why so many populations of marine species are shrinking. They and others predict that the reductions will be in the range of 20–30 percent if ocean temperatures continue to climb due to climate change.

    At the higher end of that range is one of the world's most important commercial fish: tuna.

    "Tunas are active, mobile, and fast-swimming animals that need a lot of oxygen to maintain their lifestyle," Cheung said. "In fact, they have to keep swimming non-stop in order to get more water through their gills to obtain sufficient oxygen. Thus, when temperature increases, they are particularly susceptible to not having sufficient oxygen to support their body growth."

    He added that for a 2 degree Celsius (3.6 degree Fahrenheit) increase in water temperature, which is approximately what is expected to occur in oceans around the world by the mid-21st century, tunas such as the Atlantic bluefin tuna will potentially decrease in body size by 30 percent.

    Sharks, many of which are already threatened with extinction, are also predicted to decrease in size, especially larger species.

    In the case of tuna, haddock, cod, and other fish consumed by humans, shrinkage is predicted to decrease potential fisheries production. Since marine ecosystems are structured in part by the body size of organisms — basically larger fish eat smaller fish — the projected changes to body sizes will likely affect predator and prey interactions, as well as ecosystem structure and functions, Cheung said.

    He said the most effective way to prevent these problems from occurring is to mitigate carbon dioxide emissions.

    "Our model projections show that the lower the emissions and thus warming, the smaller is the change in body size," Cheung explained. "Also, overfishing is reducing fish body size, so eliminating overfishing can help to reduce the extent of fish shrinkages."

    Meeting the emissions reductions targets of the Paris agreement on climate change would also bring substantial benefits, he added.

    The researchers believe that the tropics will be hardest hit by a reduction in fish body size since coastal communities in these regions are very dependent on fish stocks for their diets.

    Not all marine species are expected to shrink. Notable exceptions include whales and other air-breathing marine mammals. They are facing other risks brought about by climate change.

    "Their problem," Pauly said, "is getting rid of heat, like cars, since their flukes serve as radiators."

  • 01/23/2019 9:36 AM | Anonymous member (Administrator)

    Recently the question was asked about how much does a Koi weigh that is a certain length? Here are some thoughts, and a few charts...

    I've never raised koi fry but I've been a fish geek most of my life and I know plenty of other who also fall into this category. Here's what I can tell you from my experience and the experience of others.

    Fish grow most (fastest) when they are young. If they are to reach their full genetic potential, they need to be grown fast when they are young.

    Young, fast-growing fish need higher protein food than older fish. Stunting a fish with retarded growth when they are young cannot be compensated for later in the fish's life. Feeding heavy and often promotes fast growth. However, you need be careful to keep good water quality as good water is essential to good health and fast growth. This can be tricky as you need to offer enough food to keep them growing but not pollute the water.

    I know a guy who used to raise angelfish. He changed nearly 100% of the water in every tank every day. People who raise discus are also water change fanatics. Changing water relates to ridding it of growth-retarding hormones.

    There are some charts which I copied off the internet, and I'll provide below - but note that the VBGF is for farmed Koi - and that most ornamental fish in home ponds GREATLY exceed the weight at which those fish would be harvested for food... Unfortunately, that means that there is not a very good correlation between size and weight for Koi - we certainly see skinny Koi and Koi that can weight twice as much and be exact same length... And the same can be said for length vs. age - it varies considerably, based on many factors, including genetics and water quality, type of food, etc.

  • 11/18/2018 4:22 PM | Anonymous member (Administrator)

    Dr Paula Reynolds describes it very eloquently, in Koi-Carp Magazine, August 2000.  "The outermost body protection for koi is the mucus coating which forms a layer known as the cuticle. 

    The mucus is comprised of natural secretions containing antibiotics, which are the proteins that fight disease. Primarily the mucus prevents the adherence to the body by pathogens such as bacteria, virus and parasites. These antibiotics produce a general response to all the harmful organisms in an aquatic environment rather than targeting one harmful organism specifically."

    The enzyme lysozyme and other secretions termed bacteriolysins, are also found throughout the mucus layer, defending the fish when under attack by diseases.  Complement is the term applied to the system of interlinks enzyme reactions that take place in the mucus layer and also in serum. The mucus layer also contains unwanted matter from skin cells which some body parasites use as a source of nutrition.  It is from this layer that the very small amount of mucus is removed to be viewed microscopically when a parasite problem is suspected.

    The consistency of the mucus layer can be changed by diseases. When nitrite is in the water the koi can take on a soapy appearance as this substance interferes with normal mucus production. In other cases the mucus becomes thicker or even watery or can be shed altogether as it mounts a variable response to health problems. A koi striped of its mucus coating becomes more vulnerable and that is why chemicals that removes it, such as formalin has to be used cautiously.

    By: Chris Neaves

  • 11/01/2018 10:56 AM | Anonymous member (Administrator)

    If you've missed the previous posts, then you may not know that the Ausies are planning to release KHV in the Murry-Darling basin in Australia to control unwanted carp.  Here is another excellent article that voices serious concerns over the government controlled planned release of KHV.

    The extermination will begin within years - an especially virulent strain of herpes virus will be gradually introduced to rivers, and the disease will rampage through the carp population, killing as much as 95 per cent.

    Carp - also known as 'blubber lips' and 'mud sucker' - are those pale-gold, pale-silver creatures that can grow to monstrous size in rivers and creeks.

    More than 100 years after being introduced into Australia by recreational anglers and do-gooder "acclimatisation societies", it's been decided the carp are causing too much damage, churning up the river bottoms and causing a nuisance, and and they have to go. Essentially Australia is looking to deploy a biological weapon against a bunch of fish.

    Their mass extermination is being called "carpageddon".

    This is not the first time we've deployed what's called "biological controls". Maybe the most notorious is the cane toad, which was introduced to control the cane beetle, and ended up ignoring the beetle and driving native species to the edge of extinction.

    Then there was myxomatosis - introduced in the 1950s, it successfully killed lots of rabbits in Australia. Unfortunately, it then spread overseas, out of control, and killed almost all of the wild rabbits in France and the United Kingdom. The lesson: Using viruses as "biological controls" is playing with fire.

    What could possibly go wrong?

    Though the plan has been around for a decade, the idea of giving carp herpes only truly captured the public's attention last year, when the Deputy Prime Minister announced $15 million funding.

    Barnaby Joyce - who threatened to euthanize Johnny Depp's dogs over non-compliance with biosecurity laws - delighted in talking up the plan during question time, things got a bit weird. "We are afflicted in this nation with these disgusting mud-sucking creatures, bottom dwelling mud-sucking creatures," Mr Joyce said, staring at the Opposition benches. "We on the Coalition are going to make sure we have a healthy river and a healthy economy because we're going to get rid of the carp."

    But not everyone is as gung-ho as the Member for New England.

    Hack has spoken with a pet management professor, a carp-fishing tycoon, and a specialist fish veterinarian who doubt government can control the outbreak of the virus and handle the scale of carpageddon.  By declaring war on the freshwater pest, they say, Australia may drown under a sea of herpes-disfigured carcasses.

    How many carp are we talking about?

    Exactly how many carp are in Australian waterways is not known with any accuracy - estimates range from two to six million tonnes. Let's say there's four million tonnes, that's the equivalent of 100 fully grown humpback whales, or 25,000 bottlenose dolphins.

    It's true that we've handled feral animal mass exterminations before.

    The most recent was in the mid 1990s - a strain of calicivirus imported from Czechoslovakia jumped quarantine and killed 10 million rabbits within eight weeks.

    "The Murray River area stank of dead carcasses because it went through so quickly and killed 80 per cent of rabbits," says Dr Braysher, a University of Canberra professor and recognised expert on the topic of feral animal management. "And that's on land - imagine concentrated in a water system."  In the case of calicivirus, the rabbits were left to rot. This isn't an option with carp. "They're going to need lots of people there to collect dead fish because once they die those fish will come to surface and start rotting," says Dr Braysher.  As they rot they'll take oxygen form the water. As that happens all other aquatic wildlife that depend on oxygen in the water will die."

    "If they don't get dead fish out of water it will have major effects."

    Apart from suffocating the other fish, including native species like Murray Cod, the release of phosphorous and nitrogen will promote blooms of toxic algae.  "If you think we have blue green algae blooms now, think about when we have massive fish deaths," says Keith Bell, probably Australia's most experienced carp fishermen.

    Apart from killing more fish, and stopping people swimming, the algae could poison the water supply of small towns."Lots of little towns still draw water from rivers," says Keith. "Their filtering system can cope with fish, but not once the fish die and become toxic."  OK, just scoop them out.  This is only possible if the outbreak of the virus is carefully controlled. If authorities lose control, and too many fish die at once, there won't be enough people to scoop them out. Controlling a virus is very difficult - so difficult Dr Braysher thinks its impossible.  "I don't think they can," he says.

    The carp herpes virus, like all viruses, spreads at an exponential rate.

    In 1-3 days of its release, the dead carp will begin floating to the surface with bleeding gills, sunken eyes and pale patches on the skin. They suffocate over about 48 hours. The survivors, horribly disfigured, will swim about infecting other fish.  Rapid response crews will travel around the countryside netting the dead fish and dumping them in trucks for landfill.

    The virus will spread through New South Wales, Victoria, and South Australia - in the Murray-Darling Basin, the catchment for Australia's largest river system, it's estimated carp are 90 per cent of the fish biomass.  According to Dr Richmond Loh, a fish veterinarian with a particular interest in koi, a species of carp, the virus spreads easily.  It can survive in water droplets on a bird's legs,  This means it could be hard to contain. Flying upstream, the bird could transport the virus hundreds of kilometres.  A single drop of viral water in Lake Burley Griffin, the big man-made lake at the centre of Canberra, right next to Parliament House, could send belly-up an estimated 10,000 tonnes of carp in a single sitting week.

    "Once the virus is out there there's no going back," Dr Loh says.

    The virus once hit one of the major recreational lakes in the US and you couldn't go water skiing because you had to dodge all these floating fish everywhere.  "The place stunk really badly."

    Even without birds couriering the virus about, it could still be spread deliberately by humans. It happened with calicivirus - some New Zealand farmers reportedly smuggled it into their own country, to kill the rabbits in their paddocks.  "The major problem I see is people who will start picking up fish with the virus and transport them upstream," says Dr Braysher.

    We can turn them into pet food or make fish fertiliser  Maybe not.

    Last year, when everyone was learning about the carp herpes plan, there was excitement around the idea that the fish could be turned into pet food or fertiliser.  There's already a company that turns carp into fertiliser - Charlie Carp - and the owner said the company could even expand production to take advantage of the increased supply. Barnaby Joyce proposed the carp could "take the place of horse manure or something".

    It turns out it's not so simple.

    Keith Bell, the fisherman who's responsible for almost all the carp exported from the country in the last two decades, says once the carp begins rotting it can't be used for either pet food or fertiliser. Even if the fish can be collected in time (a matter of hours after they die, he says), the volume would probably overwhelm processing facilities. Carp isn't being used for pet food at the moment, and the fertiliser industry only processes a couple of hundred tonnes per year, according to Keith. "Two to three fishermen keeps Charlie Carp in enough fish for a year," he says. "The domestic human consumption market is 50-60 tonnes a year at a reasonable price.  "It's a wasted resource," says Bell, who was exporting a couple of thousand tonnes of carp per year from Australia from the late 90s until last year, when he sold up and moved to Mississippi.

    "I don't know what the right answer is, but I know this isn't the right answer." Why aren't we exporting more carp, or just eating them?

    The irony is that carp is one of the most farmed fish in the world. In Europe and China, it's considered good eating. Australia is the only carp-culturing country that hasn't had any reported cases of carp herpes. We're deliberately spreading a virus that other countries are desperately getting rid of - the same way we're trying to get rid of carp. The double irony is carp were originally introduced into Australia for human consumption - either released for recreational fishers or raised in fish farms.

    "In fish markets in Sydney or Canberra you can buy carp for $6 a kilo," says Dr Braysher. "People who want them will like them and pay big money for them.  "It's an attitude thing."  Keith Bell says exporting carp from Australia is no longer financially viable.  He says restrictions placed on what equipment he could use to catch the fish - restrictions to minimise the bycatch of native fish - made fishing carp too expensive. There's the bind: by relaxing restrictions to boost carp exports, we'll also be getting rid of native fish.  Keith closed his export business last year. He says he was the last person to export carp from Australia.

    You can't get rid of herpes

    Once the virus is released, it can't be removed. From the moment of the release, expected to be late 2018 or early 2019, there will always be herpes in Australian carp.  There will also always be carp. It's estimated within 10 years the virus-resistant fish will breed up to 60 per cent of the current population.  That means in 10 years time we'll still have a carp problem, and the carp will have a herpes problem.

    Dr Braysher says the carp are here to stay.

    "No established pest in Australia has ever been eradicated," he says.  He says river health and native fish stocks had begun to decline well before carp began to dominate the Murray-Darling river basin in the late 1960s and early 1970s. Getting rid of carp will create a window of opportunity, before they breed back up, to improve river health and native fish stocks to prevent carp once again dominating the system.

    To do this, we have to do more than blame the carp, he says. We have to look more closely at politically-sensitive things like agriculture.  We need to stop cattle getting into the river and destroying vegetation, destabilising banks and churning sediment."  "We all play a part in the degradation of the system, it's not just one individual thing.  "The pest is there taking advantage of a modified system."  "Treating carp is only treating part of the problem."

  • 09/21/2018 2:38 PM | Anonymous member (Administrator)

    By Syd Mitchell

    An interesting question has been asked:  “If an air pump is turned off for an hour in the evening, does the dissolved oxygen in the pond water disappear immediately the air pump stops?”  (The pond has an aerated bottom drain and I assume the air is being turned off so that the Koi can be seen more clearly).

    I could approach the answer from a technical point of view but it is much simpler to draw a comparison with a situation that we all have experienced and can relate to.

    A pond can be compared to a room that has an open window.  Assuming there is no wind to influence the situation, the slow, but steady, air flow through this window will provide adequate ventilation for a small number of people.  As the people in the room breathe in oxygen and breathe out carbon dioxide, the level of oxygen will decrease, and the level of carbon dioxide will increase.  With only a few people in the room, this change will not be noticeable and they will breathe comfortably.  The larger the area of the window, the greater will be the number of people that can occupy the room.

    In comparison with a pond, the open window is equivalent to the surface of the pond.  The greater the surface area, the greater will be the number of fish that can live in it using just the natural gas exchange at the surface to provide them with oxygen and to remove the carbon dioxide that they produce.  In a lightly stocked pond with a large surface area, there will be enough exchange of gasses through the surface area alone and additional aeration will not be needed.

    If you want to increase the number of people that a room can hold, you could blow air into the room by means of a ventilation fan.   This will not only introduce more fresh air into the room, but in doing so, it will also push stale air out of the window and prevent carbon dioxide from building up. The more powerful the fan, the more people will be able to use the room in comfort.  This would be the equivalent of putting air stones into a pond. The faster the air is introduced through these air stones, the faster the oxygen in the water is replaced and the faster the carbon dioxide is removed, so therefore, the greater the number of fish the pond could hold. 

    If you were to turn off the ventilation fan when the room is full, the occupants will not immediately feel the effect but, after a while, as the oxygen is being used up, they will find it harder to breathe.  There will still be some ventilation through the open window, but this may not be enough to prevent the occupants from suffocating.  It all depends on how many people are in the room, as to whether the open window will supply enough fresh air for them to breathe in comfort, or at least survive until the fan is turned back on.  Whether the room is being used for aerobics or for yoga classes, and the number of occupants are factors deciding for how long the ventilation can be turned off. Similarly, in a pond, active fish consume oxygen at a greater rate and also, the more fish there are, the shorter will be the time they can be left without additional aeration.

    If you turn off an air pump for any length of time and don’t want to spend that time doing regular oxygen tests, then watch your fish. They will tell you whether or not they are finding it hard to breathe.  If they are carrying on as normal, everything is fine.  If they start showing greater or more rapid gill movements, or if they spend more time at the surface, they need more air. As a “rule of thumb”, with good aeration and normal stocking rates, there will be a reservoir of dissolved oxygen in the water that will be adequate for them to breathe for an hour or so after the air is turned off.

    A few points you should bear in mind.  The warmer the water, the less oxygen it can hold.

    Saturation values of oxygen in fresh water at sea level (Maximum level of oxygen a pond can hold)

    Koi are happy with an oxygen level of 7 to 8 mg/L (7 to 8 ppm).  They need a minimum oxygen level of 6 mg/L to be comfortable, and they will die quickly if the level falls to around 3 mg/L. So don’t push your luck! As soon as the first fish looks slightly “out of breath”, the oxygen level will be dropping below the lowest acceptable level, so turn the air back on immediately and don’t leave it off for anywhere near as long next time.

    It is a sensible idea, if you feed Koi when the air is off, to bear in mind that as the protein in their food is digested, they produce ammonia. The nitrifying bugs (nitrosomonas and nitrobacter) in the biofilter will soon get busy converting this into nitrite and then into nitrate.  In order to do this, they will use a huge amount of oxygen, which they will also take from the water. Unless there is sufficient continuous aeration in the filters, the water returning to the pond will be depleted of oxygen. As this mixes with the rest of the pond water, it will dramatically shorten the time during which aeration in the pond can be turned off. 

    It is never a good idea to turn off the air supply to the biological chamber of the filter unnecessarily.

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