hmm things that are sensitive arent usually over cheap, just for that reason. they die a lot. lol. royals are prob the most sensitive. otos would be good, but they would be to small. what do you have in there at the moment? plecs are normally ok with ok water. you could always try a larger cory in there, they are sensitive. or a pakistani loach.Yeah, I've still gotta find something sensitive, and cheap, but not too small that it will get eaten.