I kept goldfish in the past, was out of it for a few years and have started again. Until today I had my fish (a fat moor) is a 30G bare bottom which I had to do around 30% WC/week to keep the nitrates under 10ppm. Today I moved it into a fertile substrate 75G. My hope is to have a planted LL/LT which needs few to no water changes. My question is; can this happen with goldfish? Posters who have these kinds of tanks talk about stocking "moderately" or "heavily" but they talk in terms of "schools of tetras" and I don't know how to translate this to goldfish N production. I just read a post where the guy had goldfish (i don't know how many) in a 30G PACKED with fast growing, high N consuming plants and still had nitrate creep. So can I do this? These fish are PIGS! I swear mine would eat a 10 oz. steak if one fell in there.