The pellets can make the water dirty quickly if they aren't eating them. If they are eating only bloodworms that isn't really good for them. Bloodworms eaten too often cause bloat, especially if it's freeze-dried. Frozen brine shrimp would be better to give them, I think. Shrimp pellets would be good if yours eat them, bloodworms once in awhile is fine. Live worms would also be good, I now feed mine live blackworms.