nothing wrong with properly raised/qted live foods.. but pellets should be apart of a healthy diet. try a sinking pellet massivore is like fish crack but plenty of other options out there. You can also try cut up peices of fish from your grocery store/fish market. getting it to eat a wide variety of foods is best long-term. imo variety is always best. my hybrid is lazy... so he takes pellets/fillets over live even though he almost always has constant access to live. Smelt are his and my TSN's favorite atm though the TSN is still an avid hunter and will eat feeders.
I have found predation of tank-mates to decrease with other species when live foods are offered routinely opposed to offering pellets and dead.. imo has somethign to do with the hunter/predetor wireing... like why tigers in zoos ect are offered "enrichment activities" vs just piles of meat like they use to. To each his own I say...
But when feeding live a QT process should always be used, and I also have a routine de-worming set-up for my live eating fish/tanks. feeding live is not just a matter of buying a bag of goldfish at the lfs and dumping them into the tank once a week ect... it requires an extra tankt o QT fish, and imo a routine de-worming program for your pets.