How long does it take piranhas to eat a cow?

Your question contains an inaccurate assumption. While piranhas are known for their sharp teeth and voracious feeding habits, they are not capable of consuming a cow.

Piranhas typically feed on fish, insects, and other small aquatic animals. They are known for their rapid feeding frenzies, where a group of piranhas can quickly strip the flesh off of a dead or injured animal.

However, their diet does not include large animals like cows, and they are not equipped to take down and consume such large prey.