Hi, I am completely new, ignorant and realise I have a lot to learn. I have moved in a new house which has a pond full of beautiful koi (I'm pretty sure although I think 1 or 2 might be in there under false pretences.) One of the fish in there seems to struggle to come up to the surface, He swims in a strange vertical way rather than horizontal, and when he isn't making major effort just sinks. He seems to employ a hit and miss technique trying to eat, mostly miss, poor thing, where the others seem to see ok and home in on the pellets ( I have at least worked out I needed winter food and sparingly). The others are all swimming about near or just under the surface and he is always invisible at the bottom I guess. Any advice much appreciated! Thank you