hey, i never had any, planned on it but i decided they would probally not live because i was planning on putting them in the small-fin nipper sort of fish tank. so i looked into them a bit. they dont need a filter or heater witch is pretty cool. a 20 gallon is actually a huuuuge tank for them so id put some small community tankmates in there. heres a link i think it touches on about everything. they are undemanding and easy to care for. the site says you can feed them bloodworms but they also eat pellets. so id get a small catfish to eat what they miss.
http://allaboutfrogs.org/info/mypets/dwarfs.html