Bloodworms freshly frozen as opposed to freeze dried are more nutritious and natural for your fish. It causes less internal complications such as constipation and fish love them, to boot. Most specially prepared packs you buy from an LFS also has the added protection of being irradiated. so you know when you feed your fish, the worms are bug free. Freeze dried are good but fish tend to eat them before they have time to absorb water so when the dried worms are in the fishes gut and water is absorbed through the fish internal system they swell and bloat the fish causing problems, especially if the've overfed on dried stuff.
flakes and pellets are fine, they have been scientifically prepared with a balance of vitamins etc in mind.
Feed frozen food in the quantity that they will eat in about 2 minutes, anything left over will decay and pollute the tank. Remember to thaw the worms first before feeding. Never throw a block of frozen food into the tank and hope the fish will eat it as it melts. It's not condusive to good fish husbandary do to this.