the fish that eat rodents birds and other small critters are designed to handle this type of food source in the wild where there is thousands of gallons of water flowing and so on, but in a small closed system we call aquariums really not a great thing i mean you can do it if you want to its the hobbyist call like piranha well they need meat so do you feed live or dead but it remains they need meat not flakes or pellets, but as for live feedings go we have to make our mind up to do so, i feed all my tangs live fish, shrimp and worms on the occasion but i know i can go to my local pet store and get the same stuff frozen, water changes would be a must, this is my 2 cents.