Humans mostly eat them, which is probably why reports of shark attacks, rare as they are, are so startling. Humans are supposed to eat fish, and not the other way around! Unfortunately, overfishing has endangered many species, such as cod and yellowfin tuna. Fish are farmed, like tilapia, and hunted as game, like marlins and other billfish. People also keep fish as pets and display them in public aquariums. Some fish are simple to maintain, such as goldfish, while others need very specific conditions in which to thrive, such as the scat.