How to Identify Chesapeake Bay Region Catfishes
Identifying fishes can be difficult, even for those with specialized training. Some groups of fishes are known to be difficult to identify (e.g., minnows and sculpins), as species look similar and distinguishing characteristics are subtle or may require a microscope to observe. Even the sunfishes (e.g., Bluegill, Redear Sunfish), although familiar to many, can be challenging to identify due to interbreeding among species. Catfishes are easier to identify than some groups of fishes, but many fish enthusiasts are unaware of the diversity in the group. The North American freshwater catfishes (family: Ictaluridae) are represented by 51 species ranging from the Blue Catfish, which can exceed 100 lbs., to madtoms that may barely reach 4 inches (Bugas et al. 2019). The purpose of this post is to provide some guidance on identification of Chesapeake Bay region catfishes, given that not all species are well-known to the public.
A juvenile Flathead Catfish (Pylodictis olivaris) collected from the New River in Virginia. Photo: Corbin Hilling.
Below the fall line in Chesapeake Bay tributaries, you may encounter 10 catfishes from two taxonomic families: Ariidae (sea catfishes) and Ictaluridae (North American catfishes; see below for example taxonomic classification for Channel Catfish). Both families have an adipose fin, scaleless bodies, barbels (whiskers), and hard spines on their dorsal and pectoral fins (Click here for catfish anatomy diagram). You can differentiate the two families by counting the number of barbels. Ictaluridae has four pairs of barbels, whereas Ariidae has fewer than four pairs of barbels. The species of Ariidae lack nasal barbels, which are located near the nares (nostrils) in catfishes from Icatluridae. Ariidae are marine catfishes with Gafftopsail Catfish and Hardhead Catfish known to occur in the Bay, but rarely (Murdy and Musick 2013). The two species are easily distinguished from one another, as Gafftopsail Catfish have long, sail-like dorsal and pectoral fins and long barbels at the corner of their mouths.
Example taxonomic classification of Channel Catfish presented as a refresher on the levels of taxonomic classification.
Fishes from Ictaluridae in the Bay region (8 species total) include species you may be familiar with (e.g., Blue Catfish) and some you may not (e.g., Tadpole Madtom). The first step to identifying the species of Ictaluridae is to determine the genus (plural: genera) to which the fish of interest belongs. Chesapeake Bay region freshwater catfishes come from 4 genera (Ameiurus, Ictalurus, Noturus, and Pylodictis). I will present each genus individually below.
Ameiurus (Bullheads, 3 species) - Bullheads in the Chesapeake Bay region include Brown and Yellow Bullhead, in addition to the White Catfish. Bullheads have large, somewhat rounded heads and reach smaller maximum sizes than do Blue, Channel, and Flathead Catfish. White Catfish have a moderately forked tail, whereas Brown and Yellow Bullhead do not. Brown and Yellow Bullhead tails are more square in shape, perhaps with a small notch. White Catfish may be misidentified as Channel Catfish, but White Catfish have a larger, wider head and lack spots. Brown and Yellow Bullhead are distinguished by the coloration of their chin barbels. Brown Bullhead chin barbels are dark in color, whereas Yellow Bullhead chin barbels are pale. White Catfish chin barbels are also pale.
A comparison of Blue Catfish (left) and White Catfish (Right) to show differences in head shape and width in Ictalurus (forktail catfishes) versus Ameiurus (bullheads). Photo: Corbin Hilling.
Ictalurus (Forktail Catfishes, 2 species) - The genus Ictalurus includes Blue and Channel Catfish, fishes with deeply-forked tails. Channel Catfish often have dark spots (but not always), whereas Blue Catfish do not. Many large Channel Catfish lack these dark spots, as males can become dark blue in coloration around spawning season. Consequently, misindentifications of Channel Catfish as Blue Catfish are common. Overall body coloration can be variable for Channel Catfish from copper/ brown or olive to grey or dark blue and thus isn't reliable for identification. Identification is aided by examination of anal fin shape. Channel Catfish have a rounded anal fin, whereas Blue Catfish's anal fin has a straight edge. The length of the anal fin has also been used to aid identification, where Blue Catfish often have 30 or more anal rays and Channel Catfish 30 or less (Jenkins and Burkhead 1994). Blue Catfish also tend to have a more wedge-shaped head.
Above: A Channel Catfish photographed in a livewell during an electrofishing survey (Photo: Dustin Smith, WVDNR). Below: A Blue Catfish angled from the James River during an outing with a recreational fishing guide (Photo: Corbin Hilling).
Noturus (Madtoms, 2 species) - Madtoms are distinguished from other Bay region catfishes as they have an adipose fin with a wide base that connects to or nearly connects to their tail (see below). You may encounter two madtoms in the Bay region: Margined Madtom and Tadpole Madtom. They are easily distinguished as the Margined Madtom has a black outline on its fins, whereas Tadpole Madtom does not. Their body shapes are also different as Margined Madtom is more streamline in shape than Tadpole Madtom, which was described by Jenkins and Burkhead (1994) as "stubby". These are small catfishes that are generally less than 7 inches in length.
A Margined Madtom collected from Toms Creek, a tributary of the New River, near Blacksburg, Virginia. Photo: Corbin Hilling.
Pylodictis (Flathead Catfish) - Flathead Catfish is the only living member of its genus. The species is distinguished from the other catfishes in the Bay region as they have a wide, flat head, square-shaped tail, and an adipose fin with a short base. Coloration is generally variable within the species with mottled shades of black, brown, olive and yellow. Flathead Catfish have a patch of light coloration on the top of their tail fin that is most visible in smaller individuals (see below). Flathead Catfish also have long backward extensions on the tooth patch located on the roof of their mouth (see below).
A small Flathead Catfish collected during an electrofishing survey on the James River near the Dutch Gap Conservation Area near Chesterfield, Virginia. Photo: Corbin Hilling.
Tooth patch on the upper jaw of a small Flathead Catfish showing the backward projections characteristic of the species. Photo: Corbin Hilling.
Although I briefly provide guidance on the identification of Chesapeake Bay region catfishes, other resources cover a wider variety of species and provide additional details on the species discussed above. Admittedly, I don't know much about apps with fish identification functionality and can't speak to your options. I usually don't take my phone with me on aquatic excursions due to a history of drops into lakes, rivers, and even a livewell (the one pictured above actually). However, there are several books to choose from for your fish identification needs in the region. In 2013, Field Guide to Fishes of the Chesapeake Bay was published providing an overview of fishes within the Bay. Another book (of which I am a co-author) on the freshwater fishes of Virginia provides guidance on fishes one might encounter in the tributaries of the Bay. Field Guide to Freshwater Fishes of Virginia features spectacular illustrations of most of the Commonwealth's freshwater fishes, in addition to descriptions to aid their identification. The book also features range maps depicting species distributions. The book provides all the information you might need to identify the fishes in the freshwater portions of the Chesapeake Bay in Virginia and the rest of the Commonwealth, but is also applicable to the surrounding states. Order a copy and get out there and enjoy the magnificent fishes the Chesapeake Bay and its watershed have to offer!
Thank you to Mary Groves (Maryland DNR), Geoff Smith (Pennsylvania Fish & Boat Commission) and Dr. Don Orth (Virginia Tech) for comments that improved this post!
Bugas Jr., P. E., C. D. Hilling, V. Kells, M. J. Pinder, D. A. Wheaton, and D. J. Orth. 2019. Field Guide to Freshwater Fishes of Virginia. Johns Hopkins University Press, Baltimore, Maryland.
Jenkins, R. E., and N. M. Burkhead. 1994. Freshwater Fishes of Virginia. American Fisheries Society. Bethesda, Maryland.
Kells, V., and K. Carpenter. 2011. A Field Guide to Coastal Fishes. Johns Hopkins University Press, Baltimore, Maryland.
Murdy, E. O., and J. A. Musick. 2013. Field Guide to Fishes of the Chesapeake Bay. Johns Hopkins University Press, Baltimore, Maryland.
Stauffer Jr., J. R., R. W. Criswell, and D. P. Fischer. 2016. The Fishes of Pennsylvania. Cichlid Press, El Paso, Texas.