Ive had this demand feeder for 2 full seasons now. I have no problem with fat koi, or vermin. The growth rate is awsome. The koi also leave all my lilys and other plants alone (I know, not a true koi pond to have plants).

Koi will eat alot during the first couple of days of getting a demand feeder. Because, they are normally starving, that is why they get so aggressive at feeding time. They have been conditioned to know that if they dont get in there and get as much as possible, their next meal will be hours away.

Now they eat at a pretty leasurely pace. A few pellets here and there throughout the day. I have also noticed an improvement in the quantity of eggs and the number of spawnings that I get each year.

If you are trying to grow-up some koi. This is the way to go. I supplement the pellets with treats. Which is a way to still enjoy feeding them.