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Care
and Breeding of Killies (Article contributed by Ronnie Lee)
Killifish are a diverse group of fish and have adapted to life where most fish would fail to survive. Small pools and temporary ponds make up the majority of the native habitat. Salt marshes, mangrove swamps and shallow streams also make up another sector of the habitat that Killifish are distributed in. Fortunately, Killifish are relatively un-demanding fish and tolerate a wide variety of conditions as their native habitat suffers extreme conditions that would kill most other fish making it possible to keep killifish in plastic kitchen containers large enough to hold a few litres of water and some sort of spawning substrate. Spawning techniques for killifish are broken into mop spawning, peat diving and switch spawning. Mop spawning Killifish are fish that will deposit their eggs on the roots of aquatic vegetation, detritus, moss, etc. Essentially, mop-spawning killifish are indiscriminate about spawning medium and will lay eggs anywhere they choose. By choosing a variety of spawning sites in the wild they ensure that at some point in time an egg will survive to hatch, even if the small stream dries up for a period of time. Mop spawning killifish are generally found in small streams and rivers, and in lakes that have water inlets. Mop spawners include Aphyosemion, Chromoaphyosemion, and Rivulus species of Killifish. For breeding mop spawning killifish, use a bare 15-30 liter tank with a small air driven sponge filter, a yarn mop attached to a cork, and another yarn mop attached to a stone that rests on the tank bottom OR Java Moss. Use this set up for all mop spawning killifish. Attempting to breed mop spawners in a community tank or a tank furnished with a gravel substrate will only provide the fish with alternative spawning sites rather than the selected site, or eggs the will be eaten by other fish, never the less you will never find fry. On
a daily basis remove the mops from the tank, squeezing out excess water.
The eggs are tough enough to survive this handling. With very clean hands,
that have been rinsed well, work your way through the mops Float the bowl in a tank to regulate temperature. Occasionally removing dead eggs with en eyedropper, you will recognize dead eggs as they are opaque. It is important to remove dead eggs immediately, chances for fungal attacks are increased when decaying eggs are present. Eggs for most mop spawning killifish require about two weeks incubation, depending on temperature. 30º C is a good temperature for a 10 day incubation. When eggs show embryonic development, eyes are visible and upon close inspection yolk sacks have been absorbed, they are ready to hatch. Often they need some assistance. I will stir the bowl of eggs gently every few hours. This seems to promote hatching while keeping other eggs intact. You may choose to remove the most developed eggs to a separate container for hatching. Some aquarists will place developed eggs into a film canister with some of the incubating water, breathe into the canister to induce some Co2 and carry the canister in a pocket for a few hours while going about other chores. I have never tried this as the stirring method always yields fry that were already going to hatch. Sometime the introduction of green water, Paramecium or microworms, into the hatching container will promote hatching and provide a good first meal for the fry. You should have a batch of Artemia nauplii (baby brine shrimp) ready to go for feeding the new fry. I usually give the first meal 24 hours after hatching. If you have a progressive range of age with your fry, as you will with this technique, you will be feeding regularly and newborns will have a chance to eat as soon as they are ready. In my experience, newborn fry don't actively start eating right away. You will not want to keep newborns with older fry as they will cannibalize each other. Switch spawners (Members of the Fundolpanchax genus) are essentially mop spawners that require a dry period like peat divers. They will lay eggs on floating and sunken mops, but the eggs need to be removed and placed in peat as described for the peat divers for a shorter dry spell. A 10-14 day incubation is about right. Peat spawning killifish (majority of South American annuals) require a different strategy than do mop spawners. In the wild these fish will dive into the mud and deposit their eggs several inches deep into the mud. This strategy for survival in the wild is due to the fact that their habitat often goes completely dry, ensuring that developed eggs are present when water returns. By burying their eggs deep into the mud, they are protected from absolute desiccation and chances that they will remain viable over several dry periods. To prepare the peat for it's "dry" incubation, carefully lift the container out of the tank. Dump the contents of the bowl into a fine mesh net large enough to capture everything. After dumping all the peat out of the bowl into the net, gently squeeze the net removing as much water as you can. I squeeze enough water out that there should be no more drips and the peat lightens in color a few shades and looses its gloss. The eggs can tolerate this squeezing, just don't do it too hard. Enough pressure to force water out, take your time and do this slowly. Place the peat into a zip logged bagged marked with the contents and estimated date for the first wetting. Bear in mind at this point, when eggs are buried deep into the substrate of a river or pond, and the pond dries up, they eggs are packed fairly tight into the soil and they are in an anaerobic environment. Most mistakes with hobbyists when they breed peat diving killifish is to keep the soil too moist and allow too much air into the container holding the peat moss. Roll the zip lock bag closed removing most of the air and keep the peat moss packed fairly tight. After the peat has been packed firmly in a rolled up zip lock bag, place it in a dark area that stays at room temp. Keep it warm dark and slightly moist for the recommended incubation period. Wet eggs dissolve in peat after one week …damp, compressed peat is the rule of thumb. Think about what it is like 8 inches deep in the bottom of a dry lakebed. Warm, dark tight and slightly damp, a very protected egg nursery. In my set up, I breed switch spawners in the same set up as mop spawners. The mops are removed, eggs placed in a bowl of Arciflavin. I use a turkey baster to suck up any eggs found on the tank bottom. Squirt the eggs into a fine mesh net and the net is reversed and dunked into a bowl of Arciflavin. Every few days I will remove the good eggs from the bowl and place them in a bag of peat for the dry period, usually I keep two weeks of eggs per bag and incubate the batch for about 2 weeks at room temp. Every two weeks I have a batch of eggs to wet. You can keep the eggs in dry incubation longer, but it is not advised to keep switch spawners dry for more than 2 months. You can also wet incubate switch spawners as you would for mop spawners, but your ratio of viable eggs declines dramatically as the protein coating of these eggs deteriorates before substantial embryonic development occurs. Experimentation is essential. Good Luck!
Ronnie Lee Singapore (Disclaimer: Ronnie wrote this article several months ago in June 02 as a beginner's guide for would-be killifish hobbyists. The information contained in the article was culled from many websites. Ronnie cannot remember which websites the information was taken from though. Ronnie isn't the kind of person who would intentionally plagiarised someone's else writings but if you feel that some of your work may have been taken without your permission, please let me know and I will remove the offensive paragraphs. Thank you, Loh K L) |