I hate coming to visit my mother in law and seeing her heavily overstocked 14g every other day. She knows nothing about fish and refuses to read up on the stuff. Makes me want to cry. I do secret water changes on her tank everytime she leaves her house...
Another thing that ticks me off is when I'm in the LFS
and see at least one rotting fish per tank, and the rest of the fish showing signs of sickness.
Fake plants... Like the really fake looking ones. Those bother me. Or tacky coral reef decor.
Bubbles of air in the background!!! Can you tell I'm a little OCD? Lol.