Why are the Red-Bellied Piranhas Bellies red?

Red-bellied piranhas have red or orange bellies primarily due to their diet and the presence of pigments in their skin. These vibrant colors can serve as a form of communication among the fish, signaling health and reproductive readiness. The coloration can also play a role in social interactions within schools, helping to establish dominance or attract mates. Additionally, the bright belly may help in camouflage when viewed from below, blending with the sunlight filtering through the water.