Originally Posted by Catfish Lover
Seems to me that you may not have enough filtration breaking down the gold fishes waste. Could it be the other tank? 4 koi in a 55 is grossly overstocked as they need to be in a pond. They produce LOTS of waste. Both tanks are overstocked. I'm thinking your filtration can't keep up with the waste they produce.
Yeah I'm trying to find a 125 gallon and building a pond for the koi if the weather would warm up. And I was thinking the same thing but I've had one tank for a year and the other for about 6 months and they've never smelt before?