Can goldfish bully each other after an injury?

Question

One of our goldfish was found outside of the pond, on the ground and the cat was sitting next to it, playing with it. We are not sure if the cat fished the goldfish out or if it jumped out, as the pond was very full due to recent rain.

The fish was put back in and seems healthy, but could have minor injury that we cannot see, as we have not examined him/her, just allowed her to swim and relax.

When I fed them the next day, one of the fish was bumping the other one out of the way when they fed (and I cannot tell which is the one that had been out of the pond). This used to happen when there was a larger fish in the pond with them and this larger fish has subsequently been put into his/her own pond.

This just may be a coincidence in the timing with the out of pond misadventure, but I know birds can peck at an injured bird. Can the same thing happen to goldfish.

Could this bullying bumping behavior be the result of being injured perhaps?

Answer 1

So, the short answer to that question is yes, but it's not necessarily bullying, it may actually be a natural reaction to a sick fish. Basically an attempt to avoid getting the same illness or because they're attracted to the damage.

It could also be that the aggressive one is the injured one (last para). In this case, it may be acting aggressive to protect itself from further injury and to get more food to help with healing.

Either way, if the aggression is the result of injury, then separating the two is probably the wisest idea, if possible.

The other possibility, which the first article mentions, is mating. It seems unlikely, given the behavior described, but given you're entering summer, the tanks are warming up and getting more light, it can't be entirely dismissed. Look for the signs of a male looking to mate (white dots on the gills and pectoral fins), signs of white spots elsewhere may mean that it has ich.