Tastier than Magikarp and less dangerous than virtually all other water pokemon, Goldeen have become a staple of the diet of most seafaring peoples. They have short lifespans and lay many eggs, so they are able to replenish their population, despite being a major food source across many regions of the Pokemon world.
This is not, however, to say that fishing them is a safe or easy task. A Goldeen's horn can break through a fishing net or rod, and some have even sunk fishing boats with well-placed attacks. Although not especially mobile on land, there have been stories of Goldeen, once placed in the boat, jumping overboard: like all water pokemon, they can breathe air as well as water. For this reason, most fishermen bring pokemon such as Bellsprout to kill them before they can escape.
Interestingly, although they normally dine on insects and plants, when ships sink and their crews drown Goldeen are not above scavenging human flesh.