- Feb 9, 2022
- Reaction score
- Northwest Florida
- Hardiness Zone
This website, link below, has a lot of information about fish waste and filters. The answer to your question is, it depends…. For 750 gal. With good filtration and fully cycled, I would say one koi or 20 goldfish, but that’s just a guess. I have had 10 happy adult goldfish in 300 gal. for five years. They are 6-8 “ long.
Koi length and weight chart. This chart also lists how much ammonia and waste they produce. Koi get heavier as they grow and produce more ammonia and waste.