Ronnie Touretsky, age 11, of Edison, New Jersey, for his question:

What is the life span of a goldfish?

The average goldfish, living in a well tended home aquarium, has a life expectancy of about five years. But this is not the best he can do under more favorable conditions. He is classified as a golden carp and, among fishes, the carp family has a famous reputation for longevity. Some specimens are reported to live as long as 50 years. These old timers often weigh as much as 40 pounds. Usually they are muddy brown, though some of their scales may bear a few tinges of bronze.

Apparently the pampered life of a home aquarium is not the best thing for the small goldfish. In the wild, his average life expectancy jumps to about 15 years. However, let's not go dump them in the nearest stream. There he will revert to his natural habits of grubbing in the mud, devouring all vegetation and polluting the water for other fishes. His offspring will revert to the muddy brown colors of their carp ancestors.