6 replies to this topic

[Michael Wolfe]

No, that is not it... I have hard copy of it laying around somewhere, but I am not at home... I will look after the holidays.

[Michael Wolfe]

Anyone have it as a PDF? I can't find it anywhere online.

Hot Tub Killies by Luke McClurg

Many aquarists out there like myself have over the last few years rediscovered the joys of keeping North American native killiefish as part of our hobby. Unfortunately, these native beauties can be somewhat difficult for the average aquarist to find if they are not in to collecting them personally, or live too far from the regions where the species they are looking for is found. This scarcity means that you need to take special care when you finally find the holy grail of killies. Once some specimens are obtained, they are loved and enjoyed until the inevitable march of time takes them away from us and the search must start all over again to replace our lost friends. If a population can be maintained over time though, with successive generations being raised and cared for, then one need not go through all the hassles of trying to replace a species every few years. So that is the crux of the issue, either breed these hard to acquire fish or throw yourself on the mercy of the collectors out there. ?But, I can?t raise fish to save my life!? you might say while reading this, and while in most instances I would agree that I too am not the most successful fish breeder, I am pleased to tell you that, for many temperate species at least, this is no longer true and I am happy to tell you how you too can ?Hot Tub? some of your favorite species of native killies.

The technique I am about to describe for you is not one I can claim as my own. It is one I have learned and modified from others .I must give thanks to other breeders for their help, insight, and vast experiences in teaching me the very system I am about to share with you. The North American killies are so poorly documented that little or no information is available to the average aquarist. Robert Rice, Ray Katula, Konrad Schmidt and many others deserve the kudos for sharing this technique. I have used this method for the last five years, and it has never failed me yet when done properly. As the title suggests, I have had my greatest success with the killifish species of North America including Fundulus cingulatis, Fundulus chrysotus, Leptolucania ommata and many others. This system also works with livebearers such as Goodeids and Mollies, as well as egg layers such as American Flagfish Jordanella floridia, and Pygmy Sunfish. I believe that with proper preparation, this technique could be used for many other species .


The most important thing to remember in hot tub setup, is preparation. It takes weeks of preparation to get a tub ready for the fish you will place in it. Nothing is more important in this preparation than selecting the right size of tub. I personally like to use the livestock tubs commonly found at feed stores that range in size from 70 to 110 gallons. The brand is not important, what is important is that these tubs are made for extended, outdoor use, and have some type of UV protection. Otherwise, you will at best only be able to use your tub for one growing season, and after that be forced to replace it. For smaller species such as the Pygmy Killifish L. Omatta, it is possible to use a tub as small as 20 gallons, such as one of the poly or plastic whiskey barrel containers sold in many outdoor stores. Let me recommend though that unless you are extremely limited on space, that you use the largest tub you can. I even have used 8 foot round ?kiddies? swimming pools, and am currently using an 8 foot poly stock tank with remarkable success.
Once you have the tub selected, you will need to place it in a suitable site. This is also critical, as it is the sun which will be fueling the tiny ecosystem you will create in your tub. I recommend as much light as possible, at least 8 hours a day exposure. The need for so much sun will become apparent a little later in this article, for now though, suffice it to say that the more sun the better for this situation. Don?t forget to make sure that the site you select is a level one also. This becomes a greater problem as the size of your tub increases and it may actually be necessary with very large tubs to put a little ?sweat equity? in to the project and shovel soil around to achieve a level surface to place your tub. One more important point to remember is never place your tub near a location where, if for some reason such as overfilling or heavy rains, the tub should spill over and some of the fish get washed out and be accidentally introduced to your local watershed. This could have detrimental effects on the local ecology, so please be wise and aware and take all necessary precautions to prevent accidental introductions.

Now that the tub is selected, and a proper place has been found for it to rest, you will of course need to fill it with water. I always make sure to remove any product labels from the inside of the tube, but other than that, I generally just place it and fill it using a standard garden hose. I don?t even use any dechlorinator or other water treatment chemicals, instead I let the tub sit for several days in the full sun and let nature do its work. I will after a few days though add some fertilizer for aquarium plants, a liquid type with lots of iron in it. Just follow the label directions for the product you choose, pour it in, and let it go for now. Throughout the growing season you will need to continue to fertilize your tub as the plants you will be introducing will quickly soak up all the nutrients out of the tub water. You aren?t ready to add plants yet, but oddly enough what you do want to add are several pieces of plain, white sandwich bread (a Robert Rice Tip). Yes, that?s correct, sandwich bread. I like to use about 6 slices per 100 gallons of water to start off with.

If all goes according to plan, you should see the water turning either cloudy or slightly green in a day or two, don?t panic, this is exactly what you want to happen. Now is the time for perhaps the most important step yet, adding live food to the water. While the days have been passing by and you?ve been waiting on your water to mature, you should have gone to a local pond or creek and scooped up a jar or two of the local water, in this you should find small animals such as daphnia which will make up the food base of your tub. If you can find no daphnia, it is possible to order starter packs from various sources online, or sometimes at local pet stores, for a reasonable price. Be sure if you seed your tubs with local pond or creek water that you introduce no predators such as dragonfly larva in to the mix. In either case, whether you purchase a starter pack of daphnia, or collect your own, once you know they are clean of unwanted invaders, dump them in to the tub. The daphnia will feed on the micro-organisms and algae in the water and bloom in a few weeks in to a huge colony.


At this point, several weeks later, your tub should now have gone through a ?pea green? stage, and the water should be clearing somewhat with huge numbers of daphnia visible swimming in the water. You may see other small organisms that have been blown in on the wind sharing your tub as well. Most of these are harmless and actually good for the tub?s ecology, but if you see predatory species such as large water beetles or dragonfly nymphs, you should try to remove them at once. By now, all the bread that you dropped in the tub originally should have disappeared; you will need to put in more now, as this is what will be the food source for your micro-organisms that your daphnia are feeding on. You will also at this point add plants to the tub. My favorite plant is water hyacinth. These plants are an invasive species in the south and it may be illegal to transport them even short distances. If you cannot legally obtain them in your area, other dense, top water plants such as hornwort will work just as well in most cases. It is also possible at this time, depending on the size of your tub, to add some decorative plants such as water lily, rushes, cattails, or other potted and floating plants. This will depend on your own sense of taste and style and you should not hesitate to turn your tub into a small garden.

After the plants have been added for a period of about one week, it is now time to add your fish. It?s taken as long as six weeks to get to this stage, but if you have properly prepared the tub, it will be well worth it. For a 110 gallon tub I recommend no more than 5 adult killifish be added, actually, a trio is more desirable, especially for the larger fish that exceed one and a half inches in length. Slowly acclimate them to the water, preferably early in the morning so they can adjust to their new environs during the daylight hours. Once they are introduced to their new tub, there is very little more you must do.

It?s now time for nature to take its course, and over the next few days as your killifish gorge on daphnia and other live foods they will come in to breeding condition. As the plants grow and cover the surface of the tub, it will provide places for the killies to deposit their eggs. When these hatch, the plants roots and leaves will provide areas of refuge for the fry, as well as breeding grounds for other live foods that will find their way in to your tub. Be sure to let the plants have free reign in your tub; don?t restrict them, at least not at first. The plants will provide cover, food, and shade for the tub and its inhabitants. I keep my tubs in the full sun of a Kansas summer, with temperatures often in the 90's and sometimes over 100, and the plant cover acts as a natural air-conditioner for the tub. It may be hot on the first inch or so of water, but reach in under the plants and you will feel a cool, refreshing refuge below that your fish will enjoy. They will automatically find the level at which they are comfortable and stay there.


This system acts as a mini-pond, by producing all the essentials necessary for your fish to be happy and reproduce. When the fry hatch, simply allow them to remain in the pond, under the cover of the plants. I have found that if there is sufficient daphnia in the water, the parents will not even take notice of the fry. One of the fun things to do is to dip a quart jar in under the plants and lift out the water filled jar to see if there are any fry to be found yet. This technique can be used throughout the summer to monitor the growth and spawning rate of your killies. Of course, if you wish, you can remove the fry and keep them in a separate tub, or move them to indoor aquariums if you wish. I would wait though until the fry are at last one quarter grown, as any smaller as this and the stress can often be fatal. If the plants become too numerous, simply remove a few, being careful to scan for the round, pin-head sized, eggs of the adults before you discard them. If you find any of the eggs, carefully remove them with fingers or tweezers, and place them gently back in the cleft of a plant root or leaf under the water line. If the water level decreases due to heat or lack of rain, be sure to replace it with water from your garden hose quickly. Never let the water level drop more than 3 or 4 inches, as that can destroy eggs as well as increase the overall water temperature in the tub.

If you live in a region with a climate that dips below 50 degrees for more than a couple days at a time in winter, then you will have to move all your adults and fry indoors for the winter. In Kansas, I try to have this completed by the end of October at the latest. If you live further north, you might have to do it sooner than that. When cleaning out the tub, first remove the plants, shaking them carefully to flush out any fish hiding in them. Then drain the tub slowly to about half of its volume. Use a net to carefully catch and lift out all the killies in the tub and transfer them to a bucket containing some of the water from the tub. When you think you have all of the fish removed, continue to carefully drain the tub until empty. Be sure to search for the inevitable straggler that your net missed earlier while doing this. Once empty, discard the hyacinth and other floating plants you can?t use indoors to the compost pile, store your potted plants, and turn the tub over and wait until next spring to repeat the process. The young killies you have raised in your tub over the summer will quickly adapt to the aquarium life, and by next spring will be ready to spawn the next generation.

I have successfully used this technique to raise hundreds of fry, from at least 10 different species of North American killifish, livebearers and pygmy sunfish. It has afforded me countless hours of enjoyment sitting by my tubs, watching the young fish feeding at the surface and interacting with each other. I have done this for single species tubs of 110 gallons or less or in multi-species ?ponds? of up to 8 foot in diameter. In the central U.S., I begin to fill my tubs in mid to late March and by early May am ready to introduce the adults into them. I hope you will give the hot-tub a try in your own back yard.

If you are unsure as to where to find local killie species, you will find help at the website of the Native Fish Conservancy, www.nativefish.org. I am a member and have found the NFC an aquarist friendly lot who love local fishes. The NFC is a great place to network with conservation, breeders clubs and adopt a tank programs. Look around because there are men and women across this country keeping native species of all types who are eager to help anyone who might be interested in this fascinating and rewarding branch of the hobby.

Until next time Happy Collecting and breeding!