Description

• Hypophthalmichthys nobilis
• Imported from China to control aquatic weeds
• Spreads via pond escapement or by deliberate release and by release of bait
• Feeds voraciously on plankton; can consume 40% of their body weight each day
• Competes with larval fish and paddle fish for food resources
• Quickly dominates fisheries and are widespread throughout the Mississippi River drainage

General Characteristics

• grow to 50+ lbs
• large scaleless head and opercle
• deep bodied, somewhat laterally flattened
• body dark gray upper to silver-white laterally
• eyes forward, below midline and project downward
• dorsal fin spine moderately stiff but not serrated
• gill rakers long, comb-like, not net-like

Links

Walleyes Unlimited of Montana-Bighead Carp

Description

• Mylopharyngodon piceus
• Imported from Asia in early 1980s by fish farmers to control yellow grub and snails in catfish ponds, and as food fish
• Spread via pond escapement or by deliberate release
• Grows very quickly and feeds voraciously on snails, clams, mussels, and aquatic insects; can eat 3 to 4 lbs of mussels per day
• Would impact native mussel and snail communities

General Characteristics

• grows to more than 3 feet long, averages 33 lbs up to 150 lbs
• broad, blunt head with slight down-turned mouth and no barbels
• body blackish brown and fins blackish gray
• ventral surface of head and abdomen whitish
• dorsal fin short and pointed with 7-9 soft rays
• anal fin set closer to base of caudal fin

Description

• Ctenoparyngodon idella
• Imported from Eastern Asia in 1963 for aquatic vegetation control in aquaculture ponds
• Spread accidentally from aquaculture facilities and intentionally introduced in canals for vegetation control
• Can eliminate vegetation, eradicate habitat for native fishes, forage for waterfowl, and increase nutrients

General Characteristics

• usually 1-20 lbs, occasionally up to 100 lbs and 48 inches long
• broad, blunt head with slight down-turned mouth and no barbels
• elongate body, somewhat laterally flattened, dark olive shading to brownish yellow laterally and white belly
• scales gray with dark-edges
• dorsal fin short and pointed with 8-10 soft rays
• anal fin set closer to base of caudal fin

Links

Walleyes Unlimited of Montana-Grass Carp

Description

• Hypophthalmichthys molitrix
• Imported from Asia in 1973 by fish farmers to control algae blooms and as a food fish
• Spreads via pond escapement or by deliberate release
• Tolerate a wide range of environmental conditions
• Grows quickly and to a large size and feeds voraciously on plankton
• Competes with larval fish and paddle fish for food resources
• Can reproduce only in rivers
• Known for great jumping ability

General Characteristics

• usually 1-20 lbs, occasionally up to 100 lbs and 40 inches long
• head and opercle scaleless with relatively large upturned mouth without teeth
• body deep, laterally compressed, usually olive-green dorsally to silver laterally, but sometimes bronze to red
• eyes far forward along midline and project somewhat downward
• dorsal and anal fin first ray spine-like

Links

Walleyes Unlimited of Montana-Silver Carp

Description

• Neogobius melanostomus
• Introduced first into the Great Lakes via ballast water
• Bottom-dwelling fish, native to Europe
• Prefers cobble, rock, riprap habitats
• Quickly dominates fisheries, can spawn several times a year
• Are aggressive and compete with native bottom-dwellers, have reduced numbers of native fish in places where it has become established

General Characteristics

• no other native fish in the Grate Lakes has the single pelvic fin
• young are solid slate gray
• usually 3-6 inches (7.6-15.2 cm) long, may be up to 10 inches (25.4 cm) long

Links

Walleyes Unlimited of Montana-Round Goby

Description

• Gymnocephalus cernuus
• Small perch-like European fish
• First introduced into Great Lakes via ballast water
• Spiny dorsal fins discourage predation
• Considered a nuisance by anglers
• Out competes perch for food; caused 75% declines in perch populations in Lake Superior

Links

Walleyes Unlimited of Montana-Ruffe

Description

• Tinca tinca
• Member of the family cyprinidae
• Introduced into Idaho in 1880’s, found throughout the Pend O’reille and the Coeur d’Alene river drainages, including downstream of Cabinet Gorge Dam
• High reproductive potential; grow to 15 inches in Idaho and much larger in their native Europe
• Would compete with native cyprinids and game fish

General Characteristics

• resembles carp
• flattened and stocky
• very numerous small scales, smaller than the pupil of the eye and deeply embedded
• one pair of barbels situated at the corner of the mouth
• dark colored rounded fins
• thick skin covered by abundant mucus

Description

• Sander lucioperca
• Also known as European pike-perch, closely related to walleye and native sauger
• Introduced into North Dakota from Finland in 1989, which resulted in a reproducing population
• Zander are thought to be in the Missouri River
• Potential impacts include displacement, predation, and hybridization with walleye and sauger

General Characteristics

• similar to walleye and sauger
• elongate head and body with prominent and pointed snout with large jaws
• 80-90 scales in lateral line, which continues on to the tail (sauger 75-88)
• dorsal fin is divided, 13-17 spines in the first (sauger 12-13), one or two spines and 19-24 rays in the second (sauger 17-19 rays)
• anal fin has 2-3 slender spines and 11-12 rays
• typically 16-20 in, although can reach 51 inches and 44 pounds
• dorsal fins have lines of dark spots on membranes and scattered dark spots on the tail (walleye have no spots on dorsal fin but have a dark blotch)

Description

• Channa argus
• At all life stages will compete for food and habitat with native and sport fish
• Adults are voracious predators, feed on other fish, crustaceans, frogs, reptiles, birds and small mammals
• Can survive underneath ice, northern snakeheads are present in siberia and would be able to survive in Montana
• Can tolerate hypoxic conditions; they are air breathers from late juvenile stage
• The use of pesticides to control or eradicate populations would likely be ineffective because of their ability to air breath and move across land

General Characteristics

• maximum size exceeds 33 inches
• similar to the native burbot
• most easily identified by the long dorsal and anal fins, dark, irregular blotches along sides, pelvic fins located beneath the pectorals, and truncate (not rounded) tail
• dorsal fin of burbot is split with a short dorsal fin in front of larger one
• burbot can also be distinguished by a single barbel beneath the lower jaw
• dorsal fins have lines of dark spots on membranes and scattered dark spots on the tail (walleye have no spots on dorsal fin but have a dark blotch)