or maybe some hermit crabs to fill up some of my empty tanks. :evil_lol: which do you think would be better. my bf really wants the hermit crabs but i'm leaning towards puffers of some sort because i don't want to buy a bunch of new equipment. it would be a species only tank, so which do you think i should get? and if it' s puffers what species and how many for a twenty gallon?