I have two very large Koi.... That will change Tuesday.... Lol.... But anytime the water temperature is above 55 degrees I give them 1 hand full each of wheat germ food.... They will go after it pretty good.... Then it just lays there..... Before I go to work alot of it is gone but not all...... By the time I get home from work all the food is gone.... In my pond I have no rocks or gravel except at the base of the waterfall.... But this afternoon Sarah and I were having coffee sitting by the pond and the largest Koi (Donald) came up to a rock that was covered with string algae .... When he finished a third of the rock was clean no algae..... So I guess my question is..... I have read somewhere that Koi don't like wheat germ food..... But they always clean up all the food I give them...I plan on switching to a high protein food when the water temperature consistently above 70 degrees..... Just wondering.... Jimmy