how big is a dwarf octopus???Nancy;105459 said:Hi and welcome to TONMO.com!
You don't have to have a 55 gallon tank for a dwarf octopus, such as O. mercatoris. (However, these are nocturnal). These can live in a 30 gallon tank. Other members have had - and do have - other species of dwarfs, but it's just because their local fish stores happened to be carrying them at the time.
It's not so hard to make the tank escape proof. If you have a smaller tank, you most likely will not have a sump (smaller tank for your filtration equipment). You can make a lid out of acrylic or plastic screen, filling in any small openings with other materials such as duct tape. Look at the Tank Talk forum for examples.