Male Piranhadon are much smaller than the females and must compete to prove their worth as mates. Young are born live in groups of around a dozen. Already five feet long at birth, a juvenile Piranhadon is already a dangerous aquatic predator, and will devour water birds, fish, amphibians, small dinosaurs, and just about anything else it can catch, including larger terrestrial animals. An ambush predator, Piranhadon tends to lie in wait near the river banks, using its sensitive barbels to detect the approach of potential prey, as its eyes are poor and can only see differences between light and dark. A surge of its enormous body, and it will lunge out of the water, taking its prey in its jaws, either killing it with a massive bite or dragging it down below the surface to drown.
Piranhadon also use their lunging ability and powerful pectoral fins to occasionally beach themselves on a shaded river bank. Once ashore, birds, lizards, and other scavengers will flock to the huge fish, picking it clean of innumerable parasites. They will remain there until heat, dryness, and the threat of suffocation forces them back in the water. Though they are the largest river predator on Skull Island, when hunting prey near the riverbanks, they should be alert all time from Vastatosaurus Rex. Female Piranhadon can be up to 50 feet long, and weigh around 14 tons with a relatively narrow, eel-like tail, and a larger, muscular body. Males rarely grow to be longer than 20 feet in length and weigh around 2 tons. Coloration looks to be greenish-black above and white below. A dorsal fin runs the length of the Piranhadon's back, while two huge pectoral fins serve to steer its bulk. Two barbels depend from the fish's lower jaw, the mouth has numerous sharp, pointed teeth, each of which are about the size of an adult human's forearm.