Question: how long do cowfish live?
Answer: Average Longhorn Cowfish Lifespan Understandably, cowfish in captivity can't live as long or grow as big as cowfish in the wild. But the average longhorn cowfish lifespan still isn't bad even when it's held in captivity. Generally, pet cowfish can live anywhere from 2-8 years and can grow up to 16-20 inches in size.