Angela Elias, age 9, of Gary, Indiana,, for her question:

Can fish distinguish colors?

There are 30,000 different fishes and so far only a few hundred of them have had proper eye examinations. The ones that have been tested are able to distinguish colors. In fact, they turned out to have very good color vision. From this we may suspect that all the other untested fishes also see colors. This is nice because the colors they see must make their watery world a lot prettier.

Many of the fishes that have been tested are the cute little blennies, who live near the beaches and in tidal pools. Experts test them by serving their food in colored containers. One color has the food, the others do not. After a few meals, the colors are rearranged in different places. If the fish goes straight to the one with the food, we know that he distinguishes it by its color.