A nightmare for lower levels & those that cross rivers frequently with land-based mounts, but can be easily dispatched of once you have a decently capable amphibious mount like Baryonyx or an Ichthyornis. However, if neither of those are available, a Parasaur will do to avoid them.
These piranhas are SOOOO annoying!One time I was passive taming and Equus and it ran into the water, Then about 2-4 piranhas came up and killed my Equus! I was so sad and I went and killed them. WildCard, If you see this lower the percentage of piranhas. Thank You!