Like was said, I was thinking about something different to feed them maybe once a month. We have Mummichong here which I believe is a type of killifish and I can probably get a few now and then. They're wild caught in the cold N. Atlantic, but kept captive at a friend's shop. No copper or anything for that matter is used there.
I recently heard of a company in Seabrook, NH that raises mysids for water quality checking. I should check into them as it's not too far from me.
Granted I'm a total noob, but I think these large live amphipods we have are awesome cuttlefish food and possibly easy to culture as first foods as I noticed hundreds of tiny ones in their tanks carbon reactor as I emptied it.