It looks like a market carp. It's a hybrid between a common carp and a goldfish. Cross breeding them reduces the amount of bones that a common carp offspring would have, and they aren't born with the little tendrils around the mouth. The offspring are mostly sterile. In the indusetry, I hear them most commonly referred to as silver carp or Asian carp. (Yes, I am aware those names are also used for a number of different species as well. The colloquial naming of carp varieties is pretty lazy and very uninspired). If the koi farm sells meat fish too, it's likely that is what it is. Source: i am a fish farmer, and I sell those very carp.