The feeders from the bait shop are cold water fish which typically have a much higher fat content than tropical fish. It's recommended not to feed them to tropical fish for this reason. Your best bet is to get your fish off of live food. What fish are you feeding these to? The next best thing would be to breed your own feeders.
I'm feeding a red tail barracuda and a rocket gar both of which pretty much won't every switch to non live food.
How big are they CR?
If you set up a tank, you can convert a bunch of them to warm water and feed them higher protein less fat foods. A fish is only as healthy as what it eats, It would be worth it, you can also collect them from streams and shallow rivers and do the same, the wild caughts are not fatty fish at all.