If you’ve had it with your saltwater aquarium, don’t send your fish swimming at the beach. Many originate in exotic places across the globe and can wreak havoc on marine environments not used to their presence.

Take lionfish, for example: not a problem in their native Pacific Ocean. Once they began appearing off the Florida coast, likely after release from aquariums, lionfish became nuisances. They compete for food with species depleted by commercial fishing and dine on fish that keep reef-destroying algae in check. Parasites leave them alone, and their spikes keep predators away. Consequently, the population of lionfish has exploded in the Caribbean, up the east coast of the United States and into South American waters.

Don’t make an ecological error. Look for another hobbyist or an aquarium shop to take your fishy friends.