Fish are weird creatures. I have 3 Tiger Barbs (one considerably larger than the other two), and they are great fish since they are so active. They are considered semi aggressive though, and I have had a few die on me. Wikipedia notes that they can be nippers if there are not enough of them. One of the ones I have now looked close to death a couple times. I thought that since it was hanging in one of the tank corners and not eating.
This morning I went to feed the fish, and noticed that the two smaller Barbs were not in good shape. One had a missing caudal fin, and the other was missing most of the same fin. When I fed the fish after work, these two were just hanging out in the corner together, and did not eat any of the food I dropped in the tank.
Tonight these two are trying to swim around the tank without much success. I’m thinking that they are expending a lot of energy going nowhere, and are not eating. Not long now.