Is there any reason I would not want any of the following in a bimac tank? * Mexican turbo snails (will they be eaten?) * Sifting sand star, knobby star (again, will they be eaten?) * Medium-sized sponge (will it deoxygenate the water?) Are there any fish (seahorses or small, quick fish) that can peacefully coexist with an octopus? Thanks in advance.