I have a 10000 litre pond that's clear and I have a decent filter and pump and some small airstones. My problem is I have probably over 100 goldfish of various colours and sizes. I have added ove the last 2 years 3 koi and 2 japanese koi from young. I think they aren't growing that quick. Don't know what to do. I can only think of the hard task of working out what ones to give away to a good home. What do people think?