Something like that. It varies some depending on the food animal you'll be raising. You need volume of feeder animals, and you need all different stages of the life cycle available in order to have a consistent available food supply of the various sizes you'll need.
I've looked into a few times, but have always come away with the decision that culturing live food for cephs is pretty much a full time job on its own, which is one of the reasons cultured foods are expensive as compared to wild collected.
You live on the island, maybe you can collect some yourself or find a bait shop nearby.