So I don't know if it's possible but could the hermits I added have eaten one of my fish... I can't seem to find it and I don't see a carcus and it didn't jump :S

doubtful on hermits hunting fish... but they will eat a dead fish pretty quickly.

Hmmm wired cause I can't find my hippo tang today or tonight and I fed and she didn't come out

That's got to be one hell of a hermit to eat a whole tang!

Ya hahah no doubt I just don't have any clue where she could be... She didn't jump and I cant find and reminence of her

And the only thing I've changed or added was crabs and snails

I would say its the cat...