Rock Bass
  • 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 anal fin: There are 5-7 spines and 9-11 anal rays.
  • The sides show a solid color or dark spots; there are 39-43 lateral line scales; the dorsal fin is mottled/spotted.
  • The sides of this specimen show dark mottling and a dark opercular flap.
  • Close-up head: The mouth is large, and there is a dark opercular flap.
  • Close-up pectoral fin: The pectoral fin is short and rounded.
  • Close-up gill rakers: There are 7-10 long, thin primary gill rakers on the 1st arch.
  • Side view of a breeder: Breeders are similar to non-breeders, but may be darker.
  • Side view of a breeder: Breeders are similar to non-breeders, but may be darker.
  • Side view of a breeder: Breeders are similar to non-breeders, but may be darker.
  • Side view of a young-of-year: Juveniles are similar to adults except for more mottling on the body.
  • Side view of a yearling: Juveniles are similar to adults except for more mottling on the body.
  • Side view of a yearling: Juveniles are similar to adults except for more mottling on the body.
  • Alternative side view.
  • Alternative view of head.
  • Alternative view of anal fin.
DescriptionSimilar Species
Sunfishes (Centrarchidae)
Mouth and snout: Mouth terminal and oblique, with pads of small teeth on the jaws. No barbels. Body patterning, color, and scales: Back and sides dark brown or olive, belly tan. Sides either more-or-less a solid color, or with dark blotches or mottling, or with indistinct dark SPOTS on each scale. Dorsal, caudal, and anal fins with dark mottling and dark spots; pelvic and pectoral fins lightly pigmented to dusky. 39-43 ctenoid lateral scales. Body shape and size: Body laterally compressed and deep, somewhat elongated; oval in cross section. Typically 150-200 mm (6-8 in) TL; maximum in Wisconsin about 300 mm (12 in).
Tail, dorsal and other fins: Slightly forked or round tail. Dorsal fin with 2 lobes, broadly joined by a membrane and appearing as one fin, the first with 10-12 spines and the second with 10-12 rays. Pelvic fins thoracic. Adipose fin absent. Anal fin with 5-7 spines and 9-11 rays.
Distinguishing Characteristics
See similar species information.
Breeding Adults
Similar to non-breeders; may be darker (photos).
Similar to adults, but more likely to have mottled and blotched markings (photos).
None known from Wisconsin.
Compare Similar Species
Lateral Scales
Bass, Rock39-43
Sunfish, Green44-51
Sunfish, Longear34-38
Sunfish, Orangespotted36-41
Opercular Flap Color
Bass, RockSolid dark
BluegillSolid dark
PumpkinseedDark with light spot at tip
Sunfish, GreenDark with light margin
Sunfish, LongearDark with light margin
Sunfish, OrangespottedDark with light margin
WarmouthDark with light margin
Gill Rakers
Bass, Rock7-10, long and thin
Bluegill13-16, moderately long
Pumpkinseed9-12, short and thick
Sunfish, Green11-14, long and thin
Sunfish, Longear9-11, short and thick
Sunfish, Orangespotted10-15, long and thin
Warmouth9-12, moderately long
Pectoral Fin
Bass, RockShort, rounded
BluegillLong, pointed
PumpkinseedLong, pointed
Sunfish, GreenModerately long, rounded
Sunfish, LongearShort, rounded or blunt point
Sunfish, OrangespottedLong, rounded or blunt point
WarmouthModerately long, rounded
Pigment Pattern on Sides and Soft Dorsal Fin
Bass, RockSides brown solid color or with dark mottling or many indistinct spots; fin mottled and/or spotted
BluegillSides dark or silver blue or bluish-olive, solid color or with dark vertical bars, sometimes fine irregular dark blue spots; fin solid, often with large diffuse spot at base
PumpkinseedSides olive or yellow-olive, with many irregular yellow-orange spots or blotches and sometimes faint vertical bars; fin solid or faint spots/mottling
Sunfish, GreenSides yellow or blue-green, with solid color, dark mottling, faint light spots or faint dark bars; fin dusky, spotted or with dark blotch at base
Sunfish, LongearSides dark bluish-olive, with solid color or light irregular spots or blotches/mottling; fin solid or faint spots/mottling
Sunfish, OrangespottedSides blue or gray, with occasional irregular orange spots, faint diffuse vertical bars; fin solid or faint spots/mottling
WarmouthSides yellow-brown or olive with dark mottling, faint spots or faint bars; fin mottled and/or spotted
Other Characteristics
Bass, Rock5-7 anal spines; 9-11 anal rays
BluegillOpercular flap slightly elongated in large adults
Sunfish, GreenRarely a few teeth on tongue
Sunfish, LongearOpercular flap greatly elongated in adults
Sunfish, OrangespottedOpercular flap often elongated in adults; large sensory pores above lip; 8-9 anal fin rays
WarmouthWell-developed supramaxillary bone; teeth on tongue
Similarity Index
Bass, RockN/A
BluegillModerately similar
PumpkinseedModerately similar
Sunfish, GreenModerately similar
Sunfish, LongearModerately similar
Sunfish, OrangespottedModerately similar
WarmouthVery similar
Bass, RockSee 1st row.
BluegillExcept as noted, these species lack a well-developed supramaxillary bone (longer than greatest width of maxillary), lack teeth on the tongue, have small (< anterior nostril) sensory pores above the upper lip, have 3 anal spines and 10-12 anal fin rays, and do not have elongated (i.e., longer than wide) opercular flaps. A long pectoral fin reaches to the front of the eye when folded forward; a short pectoral fin does not reach to the eye. A long gill raker is five or more times as long as wide; a short gill raker is less than three times as long as wide.
PumpkinseedSee 1st row.
Sunfish, GreenSee 1st row.
Sunfish, LongearSee 1st row.
Sunfish, OrangespottedSee 1st row.
WarmouthSee 1st row.