Dinner Time at the Red-Bellied Piranha Habitat! In this video, our fifteen red-bellied piranhas enjoy carnivore pellets dropped by aquarist Mackenzie. Although piranhas are often portrayed as ferocious predators in pop culture and media, these shy fish are opportunistic and omnivorous scavengers and much more likely to hide than to bite. Do you see those golden-glittery flecks on their bodies? For red-bellied piranhas, sparkles are more than just great fashion sense! These are called iridophores