Are these goldfish? There is a pond forum here, so you might wish to post on it. Link below. I don't really know a lot about ponds, but we do have goldfish in a pond, so here's our experience.

Their metabolism slows as the water becomes colder, and they cannot eat. We rarely feed them when it's cold because they do not eat. Did they eat the bread? If not, it will just fall to the bottom and foul your water.

We've had a couple fish over the years which grow tumors on their bodies. It apparently doesn't harm them much, or if it does, it's a slow process. We do not worry about it. Maybe there is another issue with your fish, don't know.

Good luck.

Here is a link that might be useful: Pond Forum

Thanks for the advice "socks12345", yes I am aware they slow down in winter. They are over a foot long now & I've had them about 10 years when they were only an inch long! The Koi are the biggest but I have 6 types of Carp....Goldfish, Comets, Shubunkens, Black Moors, Fantails & the Koi of course. You are correct about the tumours. It doesn't harm them until the other fish start picking at them, then it is not only unsightly but also open to infection. It is expensive to treat the entire pond so sometimes I will catch an affected fish & place it in isolation (a bucket with a bubbler to aerate it & netted in case they jump) for a couple of weeks. I haven't had any success treating sick fish, they normally end up dying. The Koi are terrible bullies! They frequently eat the babies & smallest fish and even bite the tails off the smaller breeds if they don't stay behind! There is a real hierarchy going on! But they are stunning to look at and have real personality! Anyway thanks again for your advice & I do have a lead on some food by one of the members in the forum & I will continue my research.

You know more about fish and ponds than I do! I only answered because the forum isn't very active and feel sorry when people don't get a reply!

You have a wonderful variety of fish. Our longest is maybe 8". One has a tumor on his "shoulder." I haven't noticed anyone picking at it; maybe koi are more prone to do that. We tried koi for a while, but had problems with raccoons fishing in the pond, so we gave up on that and just use tiny goldfish (called feeders here) which grow to a good size over the years. They seem the hardiest, even compared to the fantails or other fancy goldfish. Your pond is beautiful.

thankyou, you are very kind....kind of you to answer people & kind of you to like my pond! Alas my pond pales in comparison to yours which looks like a Balinese Resort or a Hawaiian hideaway! Good on you! Well done!, I just adore it! yes, Koi are predatory but beautiful! Koi are originally from Japan, when they get over a meter long & beautifully coloured they can fetch $20 thousand plus! There have been ridiculous prices paid for extra special ones (in the millions) but obviously some people have more money than sense. Koi can also live over 200 years! The oldest on record was 226! btw I have transferred this request of mine to the pond forum as you suggested & received some good advice...regards........

Great!