Putting fish in a cycling tank without doing water changes periodically.
not feeding fish, just because.
not feeding fish, because you are tires of them.
not doing water changes.
putting fish together that aren't compatible.
Goldfish in bowls, or ANY fish for that matter!
dying fish.
keeping fish in to small a tank.
touching fish without their consent (ex. Chasing mollies with hand, counter example. Petting a cichlid that will let you).
same as pops, the list could go on forever!
Hello; How do you get permission from a fish to touch it?