I'm currently treating a nasty bacterial outbreak in my pond. I have noticed that one of the more healthier fish is going around biting at the other fish. He is aiming his attentions at the listless fish with fungus on them. Is he doing them a service with his cannibalism? Or is this behaviour just annoying and stressful to the other fish?

I could remove him to another pond if this is a problem.

Thank you. :(

Almost certainly annoying and stressful I'm afraid. However, if you have a bacterial and/or fungal problem in one point I would not move fish to another one - they may take any infection with them even if they do not appear symptomatic at present.

Check your water quality and rectify any problems first and foremost, then treat the whole pond, or try and isolate and treat infected fish (e.g. in a tank). Bear in mind that many fish meds use copper compounds that are very tough on invertebrates so dosing your whole pond will have consequences for any wildlife.

Good luck getting your fish happy again!