The swamps, bogs and ponds of Tibia are not exactly known to be the cleanest of places. Of course you can also find a lot of frogs, snakes and toads in those areas - but none of them is as vicious as the Filth Toad. It is a creature attracted by extremely dirty waters and it is somewhat tougher than a normal toad. Filth Toads are generally very old and quite possibly they have already fought for their survival since several decades.