At least 20 percent of illegal fish introductions documented by Montana Fish, Wildlife and Parks have occurred in the past ten years. In total there have been more than 400 unauthorized fish introductions in waters across the state, involving 49 species of fish.
You may not know it, but it’s illegal for anyone except FWP to introduce/stock fish into surface waters of Montana or to introduce/stock fish into a private pond without a permit from FWP. This includes buying/catching fish or live fish food organisms and intentionally releasing them into surface waters, catching a fish in a creek or river and releasing it in an adjacent pond (or vice versa), or releasing goldfish or other “pet” fish that have outgrown the home aquarium into a lake, pond or stream.
Illegally introduced aquatic species can: harm native, wild, and stocked fish populations through competition, predation, and food chain disruption; spread disease and parasites; impact water quality and aquatic habitat; increase fishery management costs by requiring planting more fish or even chemical rehabilitation to maintain or restore a fishery; and diminish fishing opportunities.
Some common sense precautions you can take to avoid illegal introduction are: don't move live fish, aquatic insects, or other aquatic organisms from one water to another for any reason; don't release aquarium fish into streams and lakes; don't release live baitfish into streams and lakes.
Taking these precautions will help protect Montana’s outstanding fisheries resources from unwanted organisms such as fish predators, competitors, parasites, and diseases.
When FWP identifies an illegal introduction, an investigation is conducted. FWP will prosecute any violator(s) and may require restitution for the costs of removing the introduced species and re-establishing the original fishery. If you witness such a crime, report it by calling 1-800-TIP-MONT (1-800-847-6668).