Hi there and welcome to the forum. Sorry for the delay, we have only been running for a few days. I hope to attract a little more people who can answer questions as well.
Anyway, back to your question. As a rare treat, it would probably be okay but what you have got to remember is that fish do have a problem processing the fat that is contained in meat. Their liver doesn't process the fat properly so if you feed them too much meat, it can cause problems. You are probably better off giving them beef heart is specially made and sold in the fish shops. This is very lean and is okay for fish.
