Aliasing fishmen → fish_humanoid
Link to alias

Reason:

This seems a like a bit of a superfluous tag.

Following precedent set by *_humanoid, this seems the way to go.

Could also be aliased to simply fish, which also currently implies marine.

A lot of these are anthro (and I'm suspecting many were tagged by the same people), so I went ahead and aliased it to fish instead.