no, a filter isn't necesary, esp. for toad tads. i've raised a LOT of tads, of the american toad and they are very similiar. i just left a big bin out side with the tads in it, filled it up with water, put it in the garage so it wouldn't overheat. put in an air stone and some driftwood and fed them every day. i never once changed the water and 27/30 morphed into lil' toads. good luck!