A Few Words about Killies
By Jim Overly
I get asked every now and then about “Killifish”, what are they, are they hard to raise, are they aggressive and such like that. Maybe by answering a few of the more common questions in this article, I can pique a little interest in these wonderful, beautifully colored little fish. After all, what could be more interesting than fish that only live for a few months in a rain puddle, lay eggs that need to be dried out to hatch, and when wet again, give you dozens of fry all at once.
First that name, “Killifish”. Sounds intimidating, but it really comes from the 16th Century Dutch word “Kil”, meaning a small body of water, even a puddle. The Dutch settlers in Africa called these little fish Killifish because they lived their entire lives in the tiniest bodies of water. When the sun finally dried the Kils after a few months the adult fish obviously perished, but not before laying numerous eggs in the soft mud bottoms. As the water evaporated, the eggs were encased in this protective covering of dirt until the next rainy season wet the soil again, causing the eggs to hatch and start a new year’s cycle of life. It is the same today as it was then. One other note of interest – with all the warfare and destruction of habitat in Africa nowadays, many species we have in our aquariums are the last remaining species on earth; they are extinct in the wild.
Generally speaking, most Killies are peaceful, even timid fish, who like small tanks and low light conditions. A bare bottom suits them just fine, or perhaps a little fine gravel with a few plants that will take the low light necessary for the fish to spawn. Generally speaking, there are three methods of spawning Killies, the first being plant spawning. More or less like the usual egg scatterers with semi-adhesive eggs, the species of Killies that spawn this way are probably the best for beginning Killie-keepers. Then there are the peat ploughers, or fish that kind of bounce into the bottom sand or peat side by side and deposit their eggs as they make furrows in the substrate. Lastly are the peat divers. These guys actually dive into the peat you have thoughtfully provided, completely burying themselves as they press side by side to expel the eggs.
Although they are not a great problem to raise, most Killies dislike any great change in their world. Once they have been acclimatized to your conditions they are very hardy and forgiving of the few slip-ups we all tend to have happen. Most important, critical really, are frequent water changes. Depending on species, use the water qualities they prefer, or you can usually switch them to your own tap water over a period of time, but you must, must change 20 or 30 percent of the water weekly, replacing it with water as close as you can get to the original.
Later in this article, we will look at the individual fish and go into a little more detail on best spawning methods. Try these wonderful fish in a small tank of your own. They are some of the most beautiful fresh water fish in the world.
We will now fly in the face of Murphy's Law - Some of the most beautiful Killifish ARE the easiest to spawn. These are collectively known as the plant spawners, meaning they will lay their eggs on the roots of floating plants (or a facsimile thereof) and most importantly, will NOT need to have a dry resting phase before they can hatch. Most of the species that fall under this heading will give you eggs that will hatch in the water they were laid in within three weeks, some even less. We'll cover a few of the more popular ones for a start.
Perhaps I should say right now that most people who raise Killifish use only their Latin names. To give so many similar species common or generic names would result in the muddling of all of them into one big mess of hybrid genetic crossbreeds with no way to save the original strains. Once you get used to speaking Latin names out loud, they are not so intimidating. The females of most genuses are indistinguishable from each other. So, it is vitally important to keep the species apart to preserve their individual beauty. They are also unbelievable jumpers, and will, without fail end up on the floor or in their neighbor's tank. So it is wise to keep different types that cannot interbreed next to each other and be sure to keep the tanks completely covered. They can and will jump through 1/4 inch spaces; so tape or seal around heaters, hoses etc.
On to the fish. The most prolific genus is probably Aphyosemion. These fish live in bodies of water that, while not being very large usually, do not dry up completely in periods of low rainfall. Their eggs therefore can develop fully and the fry grow to adults without much danger of their habitat disappearing. Most will lay semi-adhesive eggs on floating plant roots and grasses hanging into the water near shaded banks. A few species of Aphyosemions will bounce along the bottom as they lay their eggs, and just to make things really interesting, some will do both or do just the opposite of what their species is supposed to normally do. Aphyosemion sjoestedti is a large, for killifish, remarkably beautiful fish that will do both, and is a very prolific spawner. They are generally easy to raise and breed for beginners to try. Aph. gardneri will typically lay eggs on higher roots and grass. Aph. akure, splendopleure, australe, and bivittatum will do so too.
These are all some of the easier fish to spawn, but everyone has different conditions that may or may not suit an individual species. The genus Epiplatys contains the species dageti, sexfasciatus, and annulatus. These fish have a pike shaped body and similar attitude. They lie in wait for an insect to come within range and shoot forward to snap it up. They are some of the most skillful at jumping through impossibly small openings. Most Epis like cooler water and lots of vegetation. They will prey upon their own fry just as readily as any other food, so care must be taken to separate the parents if you want to propagate this genus.
All these plant spawners prefer to lay their eggs on our sometimes hard to grow greenery, and to make things a bit tougher on us, they like dimly lit tanks and cooler water. Temps of 65 to 70 degrees F will suit them fine, so no heater is usually needed. But most plants need more light and warmth than what the fish want. Java moss is the standby for killi-keepers who want live plants, but there are alternatives. To insure the safety of the eggs and the fry after they hatch, you must separate them from their parents. The easiest way to do that is to remove the plants they spawned on and put these plants in a separate tank for three weeks to hatch. A trick most killie-keepers use is to make a mop head out of acrylic yarn to substitute for the plant. If the fish can tell the difference, they don't seem to mind much. The normal set-up for breeding plant spawners is a bare 2-1/2 or 5 gallon tank with a small sponge filter and one or two yarn mops floating in them. To make the mops, tie 20 or 25 strands of acrylic yarn, 20 inches long, together in the middle and then tie that to a large cork. No gravel is wanted, but sometimes a mop head on the bottom will entice the fish to spawn there.
The fish will swim into the hanging strands of yarn and lay their eggs as they pass through. They will do this continually everyday as long as they are well fed with frozen foods and have frequent water changes. You may either lift the mops out of the water, squeeze them dry with your hands and pick off each egg (they're tough shelled), or just put the whole mop in another tank with similar conditions. If you really want to make sure you have success, put the eggs you hand pick into a small jar or petri dish with a half inch of water over them and a tiny bit of fungus guard added. Watch this for a few weeks and remove the fry as they hatch.
Feed all the new fry baby brine shrimp for the best results. Other live foods that are small enough will be eaten also, but the best is to hatch out the shrimp and feed them for the first couple weeks. After that you can wean them to frozen foods of the right size. If you want to do it the easy way, you will still end up with good numbers of fish. When you have put the mops in the second tank, start your feeding regimen about two weeks after the first eggs were laid and continue three weeks after you switch the mops to the new tank. This ensures all the eggs will have hatched. Keep a lot of vegetation in the nursery tank the first couple months because siblings will prey on smaller siblings.
How would you like to take a bag of dirt off of a shelf in your closet, dump it in a jar of water and have a school of killifish fry swimming around in it 4 or 5 hours later? It really is that simple, although it does take a little work two months prior to that wetting, but not all that much. These are typically known as the dirt spawners, and they lay their eggs in the bottom sediments of their stream or pond type habitats.
Perhaps you've heard of some of these fish that spend their entire lives in puddles as small as a cow's hoof print. This obviously isn't the norm, but the fish do live in temporarily filled puddles, ponds and small streams that disappear during the dry season. For the species to survive, they must hatch out, grow to sexual maturity and breed in the space of a few months. The eggs they have laid will survive the seasonal desiccation and hatch when the next rainy season again fills their habitat with water.
We simulate this natural occurrence by providing a pair or trio of killies with a container of garden peat moss set inside their five-gallon tank. A wide mouth glass olive or pickle jar works well for this since it stays in one place on the bottom. The peat has to be fine enough to allow the fish to plow through it without sticks and debris harming them, so the bagged variety has to be put through a screen. An easier way is to find “Jiffy-7” seed starter packages in the garden section of discount stores. Remove the netting surrounding the tablet of peat and drop it in a glass of water. In a few hours there will be about a cupful of soaked peat. Put this in a strainer and rinse the very fine particles from it. Put what is left in the jar and add water to the very top. It is best to let this settle for a short while. Now comes the tricky part. Very gently lower the jarful of peat into the fish tank. The fine peat tends to roil into the water easily so some people find it works to cover the top with a flat piece of glass that can be slid off sideways after the jar is on the bottom.
All that needs to be done now is to wait. The fish should find the peat moss and start spawning in a day or two. If some of the peat has escaped the jar into the tank, it will not matter. If you wish you may siphon it out with normal tank maintenance, but it will harm nothing. The male will sometimes take up residence over the peat and entice or drive the females into it with him. After a week or better you may remove the jar with the peat and hopefully a couple dozen eggs. Replace that jar with another that has been set up the same way. The fish will spawn continually as long as they are healthy and well fed.
The jar that has been removed can now be emptied into a fine mesh strained again, but this time you will not rinse it. Let the water drain out and press the peat gently with your fingers to expel even more of the water. The peat should now be compressed enough to let you tip the strainer upside-down onto a few layers of paper toweling and tap the chunk of peat out. Lift the toweling and peat onto a stack of folded newspapers about thirty layers of paper thick. Over the next few days, a lot of the water will soak into the papers. The peat should end up damp but not wet, nor should it be turning the light tan it becomes when it is completely dry. A little experience will teach you the right dampness to store the eggs at. Put the slightly damp peat in a Ziploc bag, be sure to label it with species, date spawned and whatever notes you want to remember, and tuck it away in a dark spot at around 70 degrees. For at least two months, or up to six months for some species, let it rest.
After the proper length of resting, the peat may be rewet. A few days before you plan to hatch the eggs, you should start a bottle of brine shrimp eggs hatching so you will have food for the little fish. Powdered dry food doesn’t seem to work well for these guys. The like meat right from the start, but your friendly local fish store operator should be able to help you with something that will work if you can’t raise shrimp. When you have everything ready, plop the eggs and peat into a shallow container of water, about an inch deep, and give it a little stir with your fingers. You want to break up the peat a little and let it all settle into the water. Check it in five or six hours and then every couple hours after that. Some species hatch quickly while others take a day or so. Look for the tiniest movement, and if you see any, look for little comma shaped fry which may be anywhere from 1/16th of an inch long to perhaps 1/4th inch.
You may either spoon out the fry with a teaspoon, suck them up with a meat baster, or leave them right in the hatching container for a week or so. If you prefer the latter, feed them a very little bit as many times a day as you can, up to every two hours. Don’t panic – three times a day is fine too. After a week or two, pour the whole lot into a two gallon tank and start the usual siphon cleaning and water changing routine, but be careful you don’t siphon out the fish as they like to hide in the bottom sediment. Check the wastewater before you dump it down the drain. Killies grow fast, so it won’t be long before the will be swimming higher in the tank.
What if you have waited two or three days and nothing has happened within the hatching container? Give it another chance. Put it back through all the steps of straining, pressing, paper blotting and storage, but only for a few weeks the second time. Rewet it and see what happens this time. And if nothing has happened and you are sure the resting period was long enough for that species, try one more time. Although it is unusual to have no fry at all the first couple times, many people rewet twice as a matter of normal spawning, even if they have a fair number hatch right off. Nature has her way of protecting the species, and it just might be that in the wild, the puddle would dry up again after a short rain. Some eggs are hardwired to only hatch after a double wetting.
So there you have it. Instant fish (after a few months of preparation that is). And now what do you do with them all?
It’s ironic that some of the prettiest freshwater fish are also some of the easiest to keep and breed. The various species have their differences, but most of them are slight, and if you follow the general good housekeeping rules of fish keeping, you will have no problems with killies. Let me first touch on water issues and then foods and finally a few tricks to get you up and running.
Water. Change it and change it often. Most killie keepers change 20 to 50% of each tank’s water weekly. Replace that water with water as close to the same conditions as possible. While killies are pretty hardy fish, they take a while to acclimate to different water conditions. That is not to say small variances will matter, but try to keep pH, general hardness, and temperature fairly close to the original. Killies are usually bred in bare 2 1/2 to 5 gallon tanks, so changing water is fast and easy. A little bottom siphoning while you drain the old water will ensure clean and healthy tanks. PH should be a little on the acid side for most killies, about 6 to 6.5 on the scale. This also helps to keep any small amounts of ammonia in the less toxic ammonium ion form. Hardness should also be low, perhaps 50 to 100 ppm for most, although fish that are acclimated to harder water will spawn readily. Hard water does have deleterious effects on the eggs themselves, as it hardens the chorion, or shell, so much that the fry have a difficult time breaking out. Some tricks have been devised to overcome this problem, as we will see later. Foam filters and air stones are nice, but one of the top breeders in the area does not use any filtration or air in his small breeding tanks at all, and he raises some of the most difficult species and wins top awards with them. Lastly, the temperatures need not be warmer than room temperature. 66 to 72 degrees will be right for all the easier killies, which covers 90% of the species out there. What could be easier – no air, no heat, small tanks.
Foods for killies present a more challenging regimen. They need live foods to really flourish. Frozen foods will keep them spawning and dry foods will keep most of them alive, but to have award winning fish, they want the live stuff. In the wild they eat mostly insects or worms and larvae from insects, depending on whether they are surface or bottom feeders. For practical purposes however, we can group them all together. Mosquito larva from stagnant water in the summer is the number 1 killie food. Unfortunately, any uneaten larva will turn into the flying pest that thinks you are the number 1 mosquito food. A better idea is to purchase black worms from your local fish store. These are not tubifex, by the way. Black worms are grown in clean water, mostly in California, and fed trout chow, or in tanks fed from the runoff of commercial trout and salmon ponds. Homegrown white worms are relished as well. Some people raise a wingless variety of fruit fly to keep their fish in top shape, but this is a time consuming task for a small return of food, albeit one of the best foods. Then there is the brine shrimp, the mainstay of killie keepers. Frozen adult shrimp is probably the most used killie food, and is the easiest to come by. Shrimp newly hatched by the aquarist are eagerly eaten by all killies, and are a must if you desire to breed any of them. The fry must have baby shrimp to survive in any quantity after hatching. Some adult killies will take flake food if they are acclimated to it.
The tricks? Nothing fancy, just mostly common sense. Remove eggs from tanks every day or at least every other day from the plant spawners. Every week or so exchange the peat containers from the dirt spawners. Put plant-spawned eggs in very shallow dishes, petri dishes work best, and watch for eyes to form in the egg. If the fry don’t hatch in a few days after you see eyes, put the eggs and a little of the water in a small vial or jar and breathe into it before capping it tightly. Put it in your pocket for a couple hours, checking it now and then. This warmth and CO2 and agitation is often enough to force their hatching. For the peat divers, after you have dried the peat and waited the recommended time period, use distilled or very, very soft water to wet them with. It seems to bring faster hatching. Also, be sure to redry and rewet two or three times before discarding the peat. These eggs do not all hatch at the same time. Use only acrylic yarn for the spawning mops if you are making them, and boil them slightly to rid them of excess dyes and such. And always read as much as you can about the various species, as they have similar, but not perfectly alike, requirements.
That’s the basics of killie keeping. They are fun, pretty and not too hard to raise. They have somewhat shorter life spans, about two years, but will breed regularly to continue their existence in your tanks. I will be ordering some new species from the AKA as soon as the weather warms up a little, so if anyone would like a couple pairs, let me know. Did I mention these are the fish that can be sent through the postal system for up to a week? They are a whole new experience in fish keeping.