Red-tailed catfish, pacus, and iridescent sharks may be sold as juveniles to hobbyists who don't realize how large these fish may eventually become; all can grown to over 3 feet in length. People who find themselves with huge specimens they can no longer care for may not always be able to find a home for them. As a last resort, hobbyists may release these fish into local waters. This is not only illegal, but it dangerous and very bad for the aquarium hobby and industry.
The Responsible Fishkeeping Initiative (RFI) is an effort on the part of concerned people and companies to put a stop to the release of anything from an aquarium into the wild. Retail fish stores participating in the RFI agree to two things: 1) not to sell these species and 2) to accept large specimens of any species from people who can no longer care for them. The stores will attempt to find a home for these fish, and if they cannot do so, the fish will be humanely euthanized.