Do fish feel guilty?

One of my fish has decided to become a carnivore. I was sitting watching TV, and looked over at my fish tank tonight to find on eof my fish eating another one. Now my fish are all "community" fish. It means that they are supposed to be friendly, but yet here was the big fish picking on the little fish. I looked for a second to figure out what was going on - to make sure that I was really seeing what I thought I was seeing and then walked over to the fish tank at which point biggie immediately stopped eating little and hid in a corner like a little kid that was caught doing something wrong. Now, what did biggie think I was going to do to him for eating another fish? I can't really punish a fish... I don't think I would know how to punish a fish. Stupid fish. He is grounded.