You do realize if for some reason the sea hare dies it could poison your whole tank right?
The only reason that it would die is if its starves from my understanding there pretty hardy. Also that's why I want to barrow one my tank could not sustain a sea hare.
I've got a sea hare. Had him for 6 months. Passing him from tank to tank. Hare alg. is not the only thing this cat will eat. He has done a great job on Diatom , Hair , even a red alg. patch. I even seen it eating Nori. I would pass it forward. ButI would have to have him back ..Because I think I have a 1 of a kind pig, which eats anything .
Sometimes they don't move around for a long time, try entising it to eat by placing it onto some algae or in this case take algae from your tank and place it in QT to see if it starts munching away.