Ornamental Fish Production and Management

9.2.12 Raising the fry

When the eggs hatch, the larvae that emerge look nothing like the parent fish. Instead, the larvae have a large, yellow yolk sac and are barely able to move, let alone swim. The larvae will feed off the egg sac until all the yolk is gone. Once the yolk sac disapperas, the hungry fry will begin to look for food. The fry of small fish can be first fed infusoria, “green water,” or egg yolk. Later these fry can be fed larger foods like whiteworms, Daphnia, Artemia nauplii, and ground flakes. These foods are good for slightly larger fry such as those of cichlids. Once the fish grow larger, larger foods like brine shrimp, larger Daphnia, flakes, insect larvae, and chopped Tubifex worms are accepted. 25-50% of the water in the rearing tank should be changed daily. Be sure that the “new” water added has characteristics like the water taken out, because fry are more sensitive to sudden changes in the water. The fry should be fed several times a day. Many species need periodic sorting by size, so that larger fish do not cannibalize smaller fish. With favourable water conditions, regular water changes, and generous feeding, the fry should grow quickly. Unhealthy and deformed fish should be removed.