Feeder Catfish is a better feeder than goldfish for several reasons. They are a very hardy fish that is capable of living in less ideal water conditions which would have killed many other fish. Being more hardy, they are less able to succumb to diseases especially in overcrowded conditions and therefore less likely to be carriers of disease.
Catfishes have very good appetite and these feeders are no different. In fact, you could gutload them like by feeding them nutritions pellets before you feed them to your predator fish that wouldn't eat pellets! They can eat until their stomach looks like they're about to burst before they will stop eating. When you find your pellets not getting eaten anymore, its time to feed them to your fish. If you overfeed them in this way, you should feed them to your fish asap. If you keep them in the feeder fish tank, you must remember to change water frequently because the waste level will shoot as they disgests the food (and they don't need long).