If you like bottom feeders, then I would definitely recommend crayfish. I have 3 small orange ones in my 36 bow front and they are very entertaining. It's very fun to watch them scuttle around and climb in the tank. If you want something that will live longer, I would suggest electric blue crayfish, since they can live about 5 years with proper care and get about 5-6 in long. As for fish, perhaps some emperor or flame tetra's could be nice, or a few honey gourami's if you want something larger. None of these are aggressive, and with my experience crayfish usually run away from other fish rather than try to nip them. Hope this helps! !