I just got 2 blackfin sharks Im not sure what exactly to feed them. The sign at the petstore said to feed them flakes but I tried that and they dont seem interested. I got bloodworms as well and they can never find them they just sink to the bottom of the tank and the fish dont notice them.
It will take a week or more for them to settle. It's normal for fish to not eat for a day or two after they've been added to the tank. Let them settle, then they should eat sinking foods like bloodworm and catfish pellets.
How are you keeping them? These are brackish/marine fish. If they were (wrongly) kept in freshwater at the store you'd need to slowly bring up the salinity in the tank. As adults (and at around 20 "long) they will need a full marine set up.
