Increasing numbers of large ornamental fish, such as this 14-inch long pacu, have been illegally released into public waters like the upper Mississippi River by owners who are no longer willing to care for these pets. - Courtesy photo by Patrick Short, Wisconsin Department of Natural Resources

Partnership efforts recently helped prevent the release of this large, unwanted red belly pacu into surface waters near La Crosse, Wisconsin. - FWS photo

Partnership efforts recently helped prevent the release of this large, unwanted black pacu into surface waters near La Crosse, Wisconsin. - FWS photo

Partnership efforts recently helped prevent the release of this large, unwanted oscar into surface waters near La Crosse, Wisconsin. - FWS photo

Reports of large, exotic fish caught by anglers, commercial fishers, and fishery resource managers in public waters have become all too common across the country in recent years. 

The causes for most of these unexpected and environmentally troubling landings are hobbyists (aquarium owners and water gardeners) who can no longer care for their ornamental fish (e.g., pacu, koi) that grew to an unmanageable size and were purposely released into nearby surface waters as a quick solution. 

Pet owners should know that the release of these fish (and the disease pathogens that may infect them) could adversely impact native fishes with serious consequences for sport and commercial fisheries. 

Faced with a dilemma like this, fish hobbyists need to learn of approved alternatives to the illegal abandonment of their aquatic pets in the wild.  One such option, now offered in western Wisconsin, is a government-business partnership that was established in 2006 by the La Crosse National Fish and Wildlife Conservation Office (NFWCO). 

Several pet retailers in this region (that do not offer these frequently problematic fish for sale) have agreed to accept and quarantine large, unwanted pet fish from owners who can no longer care for them.  Because there is virtually no market for these businesses to re-sell such large fish to other pet owners, the La Crosse NFWCO will accept custody of these unwanted fish and humanely euthanize them at no cost.

Due to this unique partnership with local businesses, the Marineland Pet Center in Onalaska (a local hobby fish retailer) recently accepted three large pet fish from owners who no longer wanted to care for them. 

The La Crosse NFWCO subsequently took possession of these tropical species on 6 November 2007: one red-belly pacu (12-inch length), one black pacu (11-inch), and one oscar (11-inch).  These fish were humanely euthanized with MS-222 (tricainemethanesulfonate) and cryopreserved later that day. 

Following preparation by a taxidermist, these colorful specimens will become part of an attractive display used during La Crosse NFWCO outreach activities to increase public awareness of potentially problematic pet fish and acceptable alternatives to the release of these animals in the wild.