Alexander Cox, age 11, of Vancouver, Wash., for his question:

HOW LARGE CAN A HALIBUT GROW?

Largest member of.the flatfish group of fish is the halibut. One kind, the common halibut, can reach a length of more than five feet and can weigh as much as 400 pounds.

A cold water fish, the halibut belongs to the flounder group and has the characteristic flat body, with both eyes on the same side of the head. Its eyes lie on the right side, which is dark brown. The left side is white. Halibut flesh has a mild, pleasant flavor.

Halibuts can be found in all northern seas. The most important fishing grounds in North America are the waters from Puget Sound to Alaska, the Grand Banks off Newfoundland and the waters of Greenland.

The Greenland halibut is smaller than the common type, growing only to a length of about 40 inches and weighing about 20 to 25 pounds.

Halibuts are saltwater fish. They usually inhabit fairly shallow water. They eat a variety of smaller fish, crustaceans, mollusks and sea birds.

Halibuts usually spawn in early spring. A female may lay as many as 2,700,000 eggs, but many of the eggs and young, which float with the currents, are eaten by larger fish.