Hmm, how big? 

Well, the largest koi I have is probably a good five pounds or more.
We bought 10 koi with which to stock our pond several years ago. Hubby dug through the hard clay soil around here, also containing tons of rocks, BY HAND. I told him to hire a younger back or two, but nooooooo
Anyway, we have a 2500 gallon pond, and the original koi recreated so we now have at least 60 fish. And that's AFTER catching and giving away 24 to our local aquarium store we got the original fish from.
There's gold in our waters since the little suckers retail around here for approximately $25 apiece, not that the local store gave us anything. Taking them off our hands was enough of a favor. Those guys and gals eat through a few hundred dollars of food every month in spring, summer and fall.
