I have tons of Aggressive fish, meaning they eat meat. 8 Cichlids, 1 big Piranhas that is 3 years old, just got 6 baby Piranhas for the 60gallon tank in my daughters room. We love our fish, so beautiful and fascinating to watch. I feed them all Frozen Blood Worms, that is Worms full of Blood frozen in ice cubes, drop a few in all tanks; they come apart like fish food. The packages last a while with 2 packs of quite a few ice cubes. Less than 10 bucks.