By Donna M. Recktenwalt
We all know that live foods for our killifish can improve health and vigor, intensify color, and boost both egg production and the viability of the resulting fry. But how can the average killikeeper feed live foods without raising them himself? Brine shrimp are available at some aquarium stores, but often are of poor quality and high price. “Packets” of refrigerated live foods are sometimes available, but are pricey for even a moderate-sized fishroom.
With the arrival of warm weather, live foods for your killies may be as close as your neighborhood pond. There you may find mosquito larvae, daphnia, and perhaps some bloodworms. Your own backyard vegetable or flower garden or compost heap may yield earthworms, aphids, and ants.
Mosquito larvae are perhaps the most easily collected of the warm weather live foods. The larvae of several species of mosquitoes, they range from pale gray to almost black in color (with a few that surprise you by being green or purple) and are good food from the time they hatch until they break free of their pupae as adults. Both daphnia and mosquito larvae usually prefer sheltered, quiet water. Most aquarists who collect their own live foods recommend still, seasonal ponds, with temporary woodland pools being particularly rich, but ditches and puddles have also proven fruitful sources. Use a fine net and move it in a figure eight pattern.
Mosquito larvae are an excellent fish food, but a few precautions should be noted. The hard, nearly round pupae should only be fed to large, hungry fish. Otherwise, you may find your fishroom and house infested with bothersome, buzzing, biting visitors. And watch out for dragonfly larvae. These look similar to mosquito larvae, but are larger. They are voracious feeders and can wreak havoc in an aquarium full of small fish.
Mosquito larvae can be cultured, as well as collected. Fill a container with rainwater, set it in an area where it will be out of the way, then add your choice of: a few old leaves; a handful of grass clippings; or a measure of skim, regular, or evaporated milk. You will know that mosquitoes have found it when you find the tiny “rafts” of eggs, which look like clumps of miniature cigars floating on the surface of the water. These rafts may be placed directly into the tanks of small fish; as the larvae hatch the fish will find them.
Daphnia are a free-swimming, filter feeding crustacean that breeds prolifically under the correct conditions. Daphnia can often be collected from the same pools that yield mosquito larvae. Daphnia can be cultured in containers placed in sunny locations and fed regularly. Daphnia are filter feeders, so require a rich growth medium for their microscopic food. Horse manure or Miracle Gro fertilizer in the water will foster good growth of “green water” algae. Other foods for daphnia include: a sugar, flour and yeast mixture; strained baby food peas or sweet potatoes; pea or potato soup mix, etc. All of these should be mixed with water and enough added to the culture to produce “cloudy” water. When it turns clear, it’s time to feed again.
Aphids are the small, usually green or black sucking insects that infest rose buds and other tender growth on plants. Aphids make a welcome addition to a fish’s diet. Small numbers may simply be scraped off their host plant and fed. Larger numbers can be collected by sweeping a fine-mesh net through suitable vegetation. Alternatively, pieces of the host plants can be clipped and temporarily emersed directly in the tank.
Ants are a major part of the diet of many killifish species in their native habitats. Collecting them may be an unpleasant chore, but if you accidentally break into a nest and find a cluster of the white eggs and larvae, your killifish will relish them.
Small earthworms are always welcomed, especially by the larger killifish. If the worms are too large to feed whole, simply chop them up into smaller pieces using an old razor blade or scissors. Blue Gularis will gorge on earthworms, and even some of the more timid species will actively fight for them.
— G.C.K.A. Newsletter, July 1997