A free pack of 66 authentic fish 3D models (8Mb, .7z file) — converted for iClone 4.0 users from the low-poly (but beautifully textured) library of models made freely available for non-profit use by the Toucan Museum in Japan. They’re in .vns prop format, and most models are about 6,000 to 8,000 polys. Pack also includes a visual species-identification sheet. Freshwater fish are included.
Since they can’t move they’re really only useful for stills work (I think we need a single-bone loop-able “wiggle bone” in iClone?) and educational use. However, the Toucan library has fully segmented 3DS files — if you wanted to break apart a body from a tail, so as to animate a moving tail. Or you could put a big tail on a flexible billboard, and have it move like a waving flag?