Killifish
by Kamryn Zeedyk
Junior Member, Age 8
January/February 2007 Issue #38
I am going to tell you about killifish. Almost everyone who has been to a pond or stream has seen groups of small silvery fish flashing through the water. These are minnows or killifish. They both belong to the Cyprinidae family. There are about fifty species of killifish in freshwater ponds, lakes, and streams in the U.S.A.
Killifish swim together in groups, called schools. Swimming in schools will protect them from predators. A killifish has a square or rounded tail fin, while a minnow’s tail is forked. The killifish is a surface feeder. A lot of killifish can live together in the same pond or stream. When it is time for a female and a male to mate, the female’s anal fin turns white when she is ready to lay her eggs. The male swims by the female’s side and presses his body against her. Many female killifish continue to mate and lay eggs throughout the summer. Some do it almost every day, laying ten to forty eggs at a time. The female searches for a safe place to leave them. The membrane on the eggs helps them stick to plants and other eggs. If the eggs are not fertilized they will get moldy. In ten days, the baby killifish will hatch. Killifish break out tail first. The newly hatched killifish are called fry. The fry do not look like their parents at first. The yolk sac remains attached to their bodies. The yolk sac provides the fry with nutrition so they don’t have to look for food right away.
A baby killifish eats mostly plankton, tiny bits of plant and animal stuff that float in the water. When they get a little bigger they eat larvae and adult insects. Killifish eat more and grow more when they stay together in schools. A killifish’s mouth turns upward. When a killifish gets older, the killifish cannot swim as fast as they could once. Male killifish generally live longer then females. Some killifish live up to five years or longer. A killifish hibernates at the bottom of a pond or stream. They become active in the spring. They swim to the surface of the water and begin searching for food.
The End