man i went through 3 FREAKING ELEPHANTNOSE before i got the hint...
some of my memorable mistakes usually involved bettas and other fish compatibility... i was like determined to keep a betta with something its not supposed to be kept with, but i didnt know that. 3 bettas, 2 gouramis, 3 tiger barbs later i switched to silvertip shark with comm fish... which worked for a couple months until my fish started mysteriously disappearing.