It drives me crazy when other people tell me the proper ways of raising my fish. Specifically non-fish people. I do daily water changes in Biscotti's quarantine tank and when my step-dad found out he flipped, telling me I am killing him and you aren't supposed to change your fishes water at all, just add new stuff. I explained ammonia and he wouldn't listen.
When we were kids, we kept all kinds of incompatible fish together. Most notably my brother kept a Betta and a goldfish together. He recently suggested I keep my 6 inch albino tiger barb in my five gallon tank with Biscotti. I said Betta are best left alone and he brought up that I should just put them all in one tank. 2 male Betta and a tiger barb. Beautifully compatible.
How about you? Ever receive bad advice from non-fish people?