Sad to say that the wifes 20 long had the heater stick in the on position. she lost all but 3 fish. :wall: I knew we should have replaced the topfin heater. my male betta that we had for about a 1 1/2 years and 2 female bettas and 3 green catfish did not make it. just wanted to let any one with a topfin heater to beware because the first one we had. the glass on it busted and now this one gets stuck on and kills almost all.