• 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 pectoral fin: The pectoral spine lacks saw-like teeth.
  • Close-up head: The upper jaw is longer than the lower jaw.
  • Notice that the adipose fin is continuous with the caudal fin with a notch between them.
  • Close-up of caudal region: The body has a solid color without a dark lateral stripe; the dorsal, anal, and tail fins show light edges; the body has a slender shape.
  • Close-up inside of mouth: There are horn-like backward lateral extensions of the tooth patch on the roof of the mouth.
  • Alternative view of the horn-like projections of the tooth patch on the roof of the mouth.
  • Alternative view of a large specimen, held by Scott Harpold, WIDNR.
DescriptionSimilar Species
Bullhead Catfishes (Ictaluridae)
Mouth and snout: Subterminal, patches of numerous fine teeth on jaws. 8 obvious barbels (4 pairs; 2 pair on chin, 1 pair on side of upper jaw (near corner of mouth), 1 pair on top of snout). Body patterning, color, and scales: Solid color. Color dark brown, dark olive, or black; belly cream. Fins and barbels lightly to moderately pigmented (chin barbels whitish); dorsal, anal, and tail fins usually with lighter margins; sometimes uniformly pigmented. No scales. Body shape and size: Body dorsal-ventrally flattened with a flattened head; in cross section approximately oval (with a long horizontal axis) to round with a flattened ventral surface. Typically 100-175 mm (4-7 in) TL; maximum in Wisconsin about 300 mm (12 in).
Tail, dorsal and other fins: Rounded tail. Single dorsal with 1 stout spine and 6-7 rays, attached by membrane. Pelvic fins abdominal. Adipose fin present, attached to caudal by a membrane with a shallow notch between them. Anal fin with 15-18 rays (including rudimentary rays).
Distinguishing Characteristics
The stonecat can be distinguished by its adipose fin, which is attached to the back and caudal fin. See also similar species information.
Breeding Adults
Similar to non-breeders.
Similar to adults.
None reported from Wisconsin.
Compare Similar Species
Tooth Patch on Roof of Mouth
Madtom, SlenderNo horn-like backward lateral extensions
Madtom, TadpoleNo horn-like backward lateral extensions
StonecatHorn-like backward lateral extensions present
Color Pattern
Madtom, SlenderNo dark lateral stripe; dorsal, anal, tail fins usually with darker edges
Madtom, TadpoleOften with pencil-thin dark lateral stripe; dorsal, anal, tail fins without darker edges
StonecatNo dark lateral stripe; dorsal, anal, tail fins with lighter edges or sometimes uniformly pigmented
Pectoral Spine
Madtom, SlenderProminent saw-like teeth on posterior margin
Madtom, TadpoleNo or a few very fine teeth
StonecatNo or a few very fine teeth
Jaw Lengths
Madtom, SlenderAbout equal or upper jaw very slightly longer
Madtom, TadpoleAbout equal or upper jaw very slightly longer
StonecatUpper jaw clearly longer than lower (i.e., subterminal mouth)
Body Depth/Std Length
Madtom, Slender<22%
Madtom, Tadpole>22%
Similarity Index
Madtom, SlenderVery similar
Madtom, TadpoleVery similar