Compatibility for Fishing Made Better, AquaCulture, Just A Few Fish and maybe Advanced Fishing. I think these are probably the most realistic..ish fishing mods from best to good.
For the animals maybe Animania which was already mentioned, Better Animals and Better Animals Plus, probably a few others out there, but these are the few I know.
If you wanted to get exotic, maybe a few mods with animals like bear, deer, pheasant or turkeys or maybe add them in yourself.