I don't know of a place where you can see fish bodies and fins separately for the Windows version of Fish Tycoon. Since most people use screenshots to create their sites and tools (and the fins are attached to the fishies when they're swimming around posing for screenshots), it would take a lot of work to separate them.

There is a MobileDB database that was created by Archmage for the Palm version of the game, but it must be run on a Palm and the graphics don't match the Windows version.

Probably the best alternative is to visit one or more of the fan sites (there are several that have been created by forum members) and take a look at the screenshots of the fishies that have been posted. Some sites do have a lot of spoilers, though, so be careful if you want to avoid such things.