there is no control on how much they eat ,think of koi like cows they eat,eat,and eat all day and all night if they could they would eat till they burst and then eat their guts:

: but they pass out before that point come its like a natural safty precaution 

: but they pass out before that point come its like a natural safty precaution 
so will my koi get bigger if they have a constant food supply or will that cost me alot of mula
cant do that
. Since those color koi are mutation they must have been very rare initially. It's logical to think that they must have kept the rare color koi together to get more color koi (inbreeding). Since they were farmers and didn't know about the inbreeding at that time, it is highly possible that the breeder koi were also inbreed. I mean why would they go get a wild koi for breeding when they already had tons of koi in their pond to conveniently choose from.
),but the Color mutations didnt acurre till 1804-1830 and were red,yellow and white colored carp
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woof i wonder if that could fit ont a Snapple cap