Ambloplites rupestris
Rock Bass

Rock Bass

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The natural history of the northwoods



  • Ambloplites, from the Greek, "blunt armature"
  • rupestris, from the Latin, "living among rocks"
  • Common name from its preferred habitat
  • Other common names include: Black Perch, Goggle Eye, Northern Rock Bass, Redeye, Redeye Bass, Rock Sunfish


  • Kingdom Animalia
    • Phylum Chordata, animals with a spinal chord
    • Subphylum Vertebrata, animals with a backbone
      • Superclass Osteichthyes, bony fishes
      • Class Actinopterygii, ray-finned and spiny rayed fishes
      • Subclass Neopterygii
      • Infraclass Teleostei
        • Superorder Acanthopterygii,
        • Order Perciformes, the perch-like fishes
        • Suborder Percoidei
          • Family Centrarchidae, the sunfishes
            • Genus Ambloplites, the rock basses


  • A stout and heavy-bodied sunfish
  • Length seldom exceeds 10"
  • Weight to one pound
  • Color
    • olive colored with brassy reflections and dark mottlings along the sides; brassy flanks with black spots
    • whitish breast and belly
    • spots on lower side form prominent horizontal lines.
    • brown mottling and faint banding on the anal, dorsal and tail fins
  • Body
    • anal fin of 6 spines
    • dorsal fin of 12 spines; the spiny dorsal fin and soft dorsal fin are broadly connected but without a notch. Dorsal fin much longer and more pronounced than the anal fin.
    • pectoral fins rounded, set low and amber in color.
  • Head
    • large mouth, extending beyond mid-eye when the mouth is closed
    • eyes red
  • Lifespan to 13 years.


  • Field Marks
    • red eye
    • dark gill flap
    • jaw extending beyond midpoint of eye
  • Distinguished from other sunfish by 6 anal fin spines and 12 dorsal fin spines.


  • Southern Canada, south through the Midwest to the Gulf of Mexico.


  • Prefers streams and lakes with clear, well-oxygenated, hard water, and boulder and sand bottoms.
  • Generally found under cover of rocks, ledges, logs, or overhanging branches.
  • Shares the same environment with Smallmouth Bass, and their food habits are quite similar, except smallmouth are far more piscivorous.


  • Minnows and other small fish; aquatic and terrestrial insects, crayfish, mollusks, and other invertebrates. Extremely opportunistic.
  • Young consume zooplankton as primary forage, adding aquatic insects and small fish as they grow larger.
  • Moves and feeds most actively at twilight, or at all hours on overcast days.


  • Minnesota Record: 2lbs, 0oz., from Osakis Lake (Todd County).
  • U.S. Record: 3 lbs, from Sugar Creek, Indiana (6/13/69)


  • True to name, often caught in streams close to the rocks near the current.
  • Seldom achieves remarkable size and usually caught when fishing for other species.
  • Considered a pest by most fisherpersons for damaging baits intended for more desirable species.


  • Spawns in spring, when the water temperature ranges from the high 60ºs into the 70ºs. Spawning coincides with that of smallmouth bass.
  • Male fans out a nest in coarse sand or gravel and guards the eggs and fry.
  • Females contain an average of 5,000 eggs, but one or several fish may deposit part or all of their eggs in a single nest.
  • After hatching, the young fish are found only in quiet water areas protected from waves and strong current. Grow 1½"-2" first year, reaching 5"-7" after 3 years.


  • A sedentary and secretive fish spending much of its time passively hiding in the shadows of underwater structures.
  • Links:

    Boreal border

    Last updated on 15 October 1999