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Bullhead Catfish Family 
                   Ictaluridae 
  Eight species of bullhead catfish in three genera are known from Wis- 
consin. The ictalurid catfishes are representatives of exclusively soft-rayed
families of North American origin. In the United States and Canada, there
are 5 genera and 39 species of catfish (Robins et al. 1980). Fossils occur
in Miocene and Recent deposits. 
  The head of the catfish is often large and flattened. The teeth of the
upper and lower jaws are minute and sharp, and are arranged in broad 
pads. The swim bladder is connected with the Weberian ossicles, and is 
involved in the reception and production of sound. An often elongate, 
adipose fin is a distinctive character. All members possess eight promi-
nent, whiskerlike barbels, sensitive to touch and to chemical stimuli; in
addition, many taste buds are distributed over the scaleless bodies of a
number of species, enabling them to locate food at night when most 
members of the family are active. 
  A well-known feature of the bullhead catfishes is the spinous ray in 
the dorsal fin and in each pectoral fin. These spines are morphologically
hardened bundles of soft-ray elements which have fused embryonically. 
The madtoms have poison glands associated with these spines, which 
are capable of inflicting a painful, but not dangerous, wound. According
to Walden (1964:195), it is probable that all catfishes are so equipped:
"The poison glands do not affect the flesh for eating purposes and do
not 
seem to bother the predator fish whose powerful digestive juices dis- 
solve any madtom or small stonecat in short order." 
  The spines of the different species of bullhead catfish can be used to
distinguish one species from another, although, even within the same 
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