But how do fish know to join a group (a.k.a. shoal) of others that look like them? Are they wired that way from birth, or do they learn by looking at the fish they were raised with?

Turns out it may be a little of both, according to new research at St. Joseph's University.

Biologists studied black and white versions of the fish Poecilia latipinna, commonly called mollies.

They raised some in isolation and others in groups. After 50 days, they put each fish into the empty middle chamber of a three-chambered tank - with a group of black fish on one end and a group of white ones on the other - and watched what happened.

Black fish raised by themselves spent more time near the chamber with the other black fish, suggesting they had some innate image of what a safe companion should look like. (White mollies showed no such preference, for reasons the researchers can't fully explain.)

But both colors of fish, when raised with the opposite color for the first 50 days, tended to prefer that opposite color when given a choice in the multichambered tank.

"There's an innate sense of choice, but that can also be altered by learning," says biology professor Scott McRobert, whose study (coauthored by former grad student Jessica Ledesma) is in the journal Ethology.

None of which has anything to do with humans, much less an Obama-esque, postracial society. But as a fish story, it may offer a new model of how animals learn.

- Tom Avril