Ninespine Stickleback
  • Side view adult.
  • Side view adult.
  • Side view adult.
  • Top view adult.
  • Bottom view adult.
  • Head-on view adult.
  • Close-up flank.
  • Close-up head.
  • Close-up mouth and snout.
  • Close-up tail.
  • Close-up dorsal fin.
  • Close-up anal fin.
  • Close-up pectoral fin.
  • Close-up pelvic fin.
  • Close-up flank and dorsal spines: There are 9 (range 8-11) unconnected dorsal spines of similar size, the flanks lack scales.
  • Close-up dorsal fin: Notice the 9 (range 8-11) unconnected dorsal spines of similar size and 9-11 dorsal rays.
  • Top view: Notice that the dorsal spines are not in a straight row, but point alternatingly to either side .
  • Close-up tail region: The tail is rounded or square, the caudal peduncle is narrow, the anal fin has one spine and 8-10 rays.
  • Close-up pelvic fin: The pelvic fins each have a single spine and an inconspicuous ray.
  • Caudal peduncle in top view: Both sides of the caudal peduncle show a wide horizontal keel.
  • Alternative side view of an adult.
  • Alternate side view of an adult.
  • Live fish inside an aquarium.
DescriptionSimilar Species
Sticklebacks (Gasterosteidae)
Mouth and snout: Terminal to slightly superior and oblique, with minute teeth on upper and lower jaws. No barbels. Body patterning, color, and scales: Solid color or sometimes mottled with irregular blotches on back; silvery, gray, brown, or tan, with dark brown mottling if present; cream on belly. No scales, but variable numbers of small bony plates along anterior lateral line, caudal peduncle, and base of dorsal and anal fins. Fins with little or no pigment. Body shape and size: Body fusiform in side view and laterally compressed. Caudal peduncle with bony horizontal keels on each side. Typically 35-65 mm (1.5-2.5 in) TL; maximum about 85 mm (3.5 in).
Tail, dorsal and other fins: Rounded or square tail. The dorsal fin consists of 8-11 (usually 9) unconnected spines of similar size followed by a fin with 9-11 connected rays. Pelvic fins thoracic and reduced to a single spine and ray. No adipose fin. Anal fin with 1 spine and 8-10 rays.
Distinguishing Characteristics
The ninespine stickleback can be distinguished by the 8-11 (usually 9) similarly sized and unconnected spines on its back. See also similar species information.
Breeding Adults
Breeding males with black belly and whitish pelvic fin membranes. Pink around head in breeding males and females.
Similar to adults.
None known from Wisconsin.
Compare Similar Species
Spines on Back
Stickleback, Brook4-6 (usually 5), simiarly sized and unconnected
Stickleback, Ninespine8-11 (usually 9), similarly sized
Stickleback, Threespine2-4 (usually 3), differently sized; first two spines much larger than the third (or forth if present)
Similarity Index
Stickleback, BrookModerately similar
Stickleback, NinespineN/A
Stickleback, ThreespineModerately similar