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Rusty crayfish, aggressive and invasive fresh-water crustaceans, have been discovered in the headwaters of the Yampa River and at Sanchez Reservoir State Wildlife Area in Costilla County. To prevent the spread of rusty crayfish, the Director of the Division of Wildlife has issued immediate orders preventing the removal of any live crayfish from Sanchez Reservoir State Wildlife Area and from the Yampa River, and any streams lakes, canals or rivers that adjoin the Yampa River.

Colorado law prohibits the use of rusty crayfish as bait anywhere in the state. Anglers collecting crayfish must either return them to the reservoir alive or immediately kill the crayfish by separating the crayfish's tail from the body, or thorax. Even crayfish harvested for human consumption must be killed by separating the edible tail from the body before leaving the reservoir.

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Whirling disease is a parasitic condition affecting fish, primarily rainbow trout. It is present in many Colorado rivers and in a number of state hatcheries.

Once the disease parasite is established in the wild, it can persist indefinitely, depending on environmental conditions.

Efforts to reduce the parasite in hatcheries are proving successful.

The Colorado Parks and Wildlife has developed strict policies and regulations to help control and prevent the spread of the disease in Colorado.

To find out how it affects fish and what you can do to help, see Whirling Disease.

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Zebra and quagga mussels are non-native barnacle-like mollusks with dark and light colored stripes. They smother aquatic organisms, such as crayfish and native clams. They can also damage boating equipment and clog water treatment facilities.

Zebra and quagga mussels spread from Eurasia to the Northeast and Great Lakes in contaminated ballast water of boats, on anchors and anchor lines. They quickly spread to the Mississippi River, its tributaries and inland lakes and have now established a presence in the Western States.

Boating regulations require mandatory boat inspections to prevent the spread of aquatic invasive species. For the most current information, including news releases, visit Mandatory Boat Inspections.

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Salmincola, often called gill lice, are parasitic crustaceans that attach to trout and kokanee in both free-ranging and hatchery populations in Colorado. The parasites attach to and damage the gills so the fish cannot properly exchange gases and waste products. This causes the fish to be very susceptible to stresses such as angling and catch‐and‐release activities.

To learn more about how gill lice is affecting fish in Colorado and prevention methods, see Salmincola .

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The Colorado Parks and Wildlife operates 16 fish propagation facilities that include hatcheries, rearing units, and a native aquatic species restoration facility. Visitors are welcome at every facility. To learn more see the Hatcheries page.

Job opportunities - Find out about a career as a "fish hatchery technician."

Kids - Put yourself 'in the shoes' of a hatchery manager! The Fish Hatchery Game mirrors a year in the life of a hatchery manager. The problems that you must solve are the real deal, and answer that age-old question of yours, "Why do I have to learn this stuff? I'll never have to use it again!" It takes knowledge and disciplined work to raise fish in Colorado. Are you up to the task?