Question
I have a 1200 gallon unshaded pond in coastal Southern California. It has a superior filtration system for my 15 koi (6"-15" fish). My pH always sits between 7.6-8.0. The koi (and the pond) have always been healthy, but any red or orange coloring seems to mysteriously disappear. Leaving white and/or black in its place. What might be the problem ???

Answer
Koi do change color with time.  If it's multiple fish changing, then it may be more than that.  Feed foods rich in caretonoids (beta and alpha carotene, lycopene, etc.).  Also, sometimes bright light will wash out fish so you might want to provide more shade if the pond is super sunny.  Ill fish may also wash out but you seem to have more of a color change occuring which could be natural changes or from the diet.  Most likely, the fish are fine (if not as "pretty").  You have a lot of fish for your pond so check the pH, nitrite, and ammonia on occasion.  Good luck!

Robyn
fishpondinfo.com