Giant LAKE KOI Fiberglass Pond - Preformed Fiberglass Ponds

koi50003. How Many Koi Can a Pond Hold? Overcrowding a koi pond leads to poor water quality, stunted growth, and stress-related diseases.. General rule: 1 koi per 250 gallons3. How Many Koi Can a Pond Hold? Overcrowding a koi pond leads to poor water quality, stunted growth, and stress-related diseases.. General rule: 1 koi per 250 gallons