Mixaill studio presents a good solution for your games, VR projects and simulators - River fish
You can use this models for your simulator games. All models low poly and have two object: fish body and fin. It good for collider.

Pack includes 25 fish. (on average 2,000 triangles each fish)
Pike
Perch
Zander
Burbot
Lobster
Rainbow trout
Lake trout
Grayling
Taimen
Whitefish
Brook trout
Ide
Volga zander
Ruff
Sabrefish
Stickleback
Zope
Roach
Dace
Tench
Crucian
Bream
Slv.Bream
Rudd

All fish have animation - Swim (includes in Perch)

Textures:
Resolutions 4096x4096
Textures types:
_Diffuse
_Normal

If you have any questions, write me: mixaill3d@gmail.com