Hey guys, i'm curious at what forms of punishment others use for their fish. 
For the longest time, one of my cichlids had been chasing the other. Now there is no reason
for that behavior so sometimes i take him out of the water with the net and squeeze him real hard.
Now it worked for a while but now he swims upside down and floats around alot.
Trust me, he is still alright, But thats mainly the reason im asking this here today.
        Is there any way we can list different ways to punish a fish and make sure it thoroughly understands what it has done? I had heard from a freind of mine he use to put tacks into them, But they ended up floating around too.
I have also heard of not feeding them for about 2 months, But i figure that wouldent work too well either.
I am looking for a legitimate way to punish my fish and still ensure that they are learning from this experience, and going to be healthy after they have learned what they have done wrong. 

   Thank you guys.

                                  Uncle Phil