Catch of the Day: The Fish Families of Ohio

This week’s lab involved taking a tour through the fish families of Ohio, guided by Dr. Sheil.  We began by covering the basics of fish morphology. The first thing emphasized was the arrangement of fins and their proper titles, which included: the dorsal fin, caudal fin, anal fin, pelvic fin and pectoral fin. The bony supports within fins are fin rays, which are softer and more flexible, and spines, which are stiffer processes. The bony plate that covers the gills is called the operculum. The line running the length of the fish’s body is known as the lateral line, and it is a sensory organ used to detect pressure changes in water.

Our lecture also covered the three basic scale types: ganoid, cycloid and ctenoid scales. Ganoid scales are the basal, or ancestral, scale type that has an upper surface covered in ganoine, which is a mineralized tissue comparable to enamel. Cycloid scales are a rounded type of scale, whereas ctenoid scales have more of an irregular shape.

Another of the basic morphological characteristics discussed were the two types of tails. The ancestral condition is a heterocercal tail, which is asymmetrical, with the vertebral column extending into the larger lobe. Alternately, the symmetrical homocercal tail type is derived and seen much more commonly in the fish of Ohio.

After learning the basics we were ready to take a plunge through the different families of fish found in Ohio. We traveled to each of the different tables throughout the lab and sketched the preserved representatives of the families, taking note of particular morphological features that will aid in identification.

Petromyzontidae: Lampreys

Lampreys are parasites of other fish. They use their buccal funnel (mouth), which is lined with cornfield “teeth,” and rasping tongue to feed of host fish. Although lampreys have a mouth, they are jawless, so they lack an operculum. The lamprey’s over all morphology resembles an eel in the sense it lacks pelvic and pectoral fins. The dorsal fin is posteriorly displaced and is fused with the caudal and anal fin. The dorsal fin can be undivided, have a wide notch between the dorsal and caudal fins, or have a deep notch between the two fins. The condition of the dorsal fin and the anatomy of the mouth are often used to characterize species belonging to this family.

Acipenseridae: Sturgeons

The sturgeon is a large, prehistoric-looking fish that has an ancestral heterocercal tail. This fish has bony plates, or scutes, that are arranged in rows running the length of the body. Under the snout, one can see 4 distinct barbels and a tubular mouth used for sucking food items off the substrate. There are two species in Ohio, Acipenser fluuescens and Scaphirhynchus platorychus. Scaphirhynchus platorychus can be differentiated due to its long, slender tail and large, bony plates on the caudal peduncle.

Lepisosteidae: Gars

Gars have a long snout that is filled with long, fang-like teeth, making them look fierce in appearance. Typically found in slow-moving and turbid tributaries, these fish turn right or left to grab prey as they swim through the water column. This fish has an elongated body that is covered with rhomboid, ganoid scales, which function as “armor-plated” protection. The dorsal fin is posteriorly displaced, which is often associated with “sprinter” fish or fish that swim near the surface. The operculum of members of this family has many bones on the “cheek” rather than just one singular opercular shield. It should also be noted the gars have an abbreviated heterocercal tail. The genus we have in Ohio is Lepisosteus.

Clupeidae: Herrings and Herring allies

Alewife specimens. Note the vertical eyelid and the ventral row of keeled scales that help distinguish this fish. (Photo credit)

This “cute” family of fish has a few unique morphological characteristics that can help in identification. First, the dorsal fin is situated almost directly over the pelvic fin. Secondly, this family of fish has no lateral line system. Also, on the underside of the fish there is a row of keeled scales that resemble saw teeth. Furthermore, the anal fin is so broad and long it almost appears to interact with the caudal fin. A particularly interesting member of this group is the alewife (Alosa pseudohasengus), which has a “bizarre” eyelid that opens and closes vertically opposed to horizontally, and is a dead giveaway for identification.

Salmonidae: Salmons, Trouts, and Whitefish

These fish have small cycloid scales which give them a smooth appearance. Both male and female fish of this family possess a bilateral axillary process located above the pelvic fin. Cameron shared that he recently completed work for a research project that utilized this fleshy process for genetic testing. Researchers remove the process without significant negative impact on the fish by clipping it with a pet nail trimmer and have enough material for genetic analysis. Another feature in this group is presence of an adipose fin which is a small fleshy fin, comprised of fat, located between the dorsal and caudal fin. The Brook Trout (Salvelinus frontinalis) and the Lake trout (S. namaycush) are two examples from this family found in Ohio.

Esocidae: Pikes

These fish look distinct because their snouts resemble duck bills and are filled with large canine teeth. Similar to gars, the pike’s dorsal fin is displaced posteriorly because this fish swims near the surface and is a “sprinter.” These voracious predators rest in the grass, wait for prey, and then shoot out to grab them with their sharp teeth. Esox is the genus primarily found in Ohio. Muskellunge and Pike are typically found in large lakes and pickerels live in small streams.

Catastomidae: Suckers, Redhorses and Buffalo fish 

The common carp (left), which is member of the Cyprinidae family, can be confused with Carpoides (right), which is a member of the Catastomidae family. The center photo shows the ventral view of both fishes. Note the striate, sucker-like lips of Carpoides and lack of barbels.

The most obvious feature of fish in this family is the subterminal mouth. The large and striated, sucker-like lips are used to adhere to substrate and suck up food, such as periphyton from rocks and logs. In Ohio, we can find the red horse (Moxostoma), the buffalo fish (Carpoides), and the common white sucker (Catastoma commersoni). We were cautioned not to confuse Carpoides with the common carp, which belongs to Cyprinidae. Carpoides superficially resembles a carp, but is distinguished by a nipple-like process on the bottom lip and a lack of barbels.

Ictaluridae: Catfishes, Madtoms

Madtom (left) and catfish (right) specimens. Note the small size of the madtom, as well as the unforked, rounded caudal fin. Alternately, the larger catfish displays the characteristic forked caudal fin. (Photo credit)

Members of this family usually have more than eight barbels around their mouth. An interesting feature lies within the fins, with both the dorsal and pectoral fins having a large spine. These fish lack scales, but an adipose fin is present. Catfish (Ictalurus) and madtoms (Noturus) can be easily confused if one does not know what specific morphological features to compare. However, adult madtoms do not get much larger in length than the distance between your extended thumb and pinky finger, while catfish can grow to be quit large. Looking at the tail can also help one decipher between the two. Madtoms have an unforked, rounded caudal fin, whereas the caudal fin of the catfish is forked.

Cyprinidae: Carp, Minnows, Daces, Shiners and Goldfish

Cyprinids have a more terminal mouth and in some species, the upper jaw has fleshy barbels that hang from it. Sometimes these barbels can be cryptic. One example of a very common Ohio cyprinid is the common carp (Cyprinus carpio). The goldfish (Carassius auratus) is distinguished from the common carp due to a lack of barbels on its upper jaw. Another group of Cyprinidae is the minnows (Campostoma), which are said to resemble “green beans” in a seine net, and can be characterized by a large “c-shaped” upper lip that causes a heavy overbite. Fathead minnows (Pimephales) have only a slight overbite, but very crowded scales on the dorsum.

Anguillidae: Freshwater Eels

American eel specimens. Note the continuous dorsal, caudal and anal fin. (Photo credit)

The freshwater eel has almost a serpent-like appearance, with pelvic fins absent and a fused dorsal, caudal and anal fin. This fish has scales so small it appears to be scaleless. On each side of the fish we find a single opercular opening. A freshwater eel species found in Ohio is the American eel (Anquilla rostrata).

Atherinidae: Sliversides

Sliversides resemble a miniature freshwater barracuda. These fish have a very flat head and back along with a “bird–beak” shaped mouth. Sliversides also have very large eyes. Running down the length of the body is row of serrated scales that stand out against the conspicuous cycloid scales of the rest of the body. Sliversides also have two dorsal fins, the first of which is shorter and has six spines. In Ohio, we find the Brook silverside (Labidesthes sicculus). When captured in a seine net, these fish are easily recognized by the silver flash on their side that reflects the light.

Moronidae: White Basses

The fish in this group have two dorsal fins, the first of which has spines that are sharp and the second just has flexible rays. The key feature for this family is a spine that is located on the opercular flap. Members of this family commonly seen in Ohio are the White Bass (Morone chrysops), the Striped Bass (M. saxatilis) and White Perch (M. americana). Moronids can be distinguished from members of Centrarchidae by the condition of the dorsal fins, which as previously mentioned, are fused in centrarchids.

Centrarchidae: Blackbass, Crappies and Sunfishes

When it comes to members of this family, attention to detail is critical for identification. Counting the number of dorsal and anal fin spines as well as examining the size of the scales is very important. In Ohio, members of this family include blackbass (Micropterus), which have fused dorsal fins and small scales. The sunfishes also have fused dorsal fins, but larger scales than the blackbass. Finally there are crappies (Pomoxis), which have 5-8 dorsal spines and 5-7 anal spines.

Percidae: Walleyes, Perch and Darters

Fish in this family generally have large, blocky heads and the body depth tends to be less than the head length. The overall shape of the body resembles a torpedo. These fish also have conspicuously paired dorsal fins and a spine associated with the anterior end of the anal fin. In Ohio, we find walleye (Stizostedion), which have a very flat belly and two dorsal fins. We also have darters (Etheostoma), which have very blunt faces and huge pectoral fins. Finally, we have the roughbelly darters and logperches (Percina) that have a more tapered face compared to darters in the genus Etheostoma, as well as significantly smaller pectoral fins.

Gobiidae: Gobies

This invasive group of fish is distinguished by its cup-shaped pelvic fin, which acts as a suction cup to allow them to withstand the current and sit in place on the benthos. As we learned in a previous lab, these voracious gobies will eat the eggs of other fish species in the time that it takes a fisherman to pose with the caught fish for a photo. There are strict restrictions on fishing activity due to the threat of goby predation on the eggs of native fish species.

Cameron labels new preservation jars as we update the JCU fish collection as Alison enjoys the aroma of preservatives. Meanwhile, Chelsea digs deep for more unknown fishes and Kim supervises the search.

We concluded the lab by helping improve the JCU Biology Department’s fish collection by identifying and sorting unknown fish specimens. Using a dichotomous key specific to families of Ohio fishes, we were able to organize mixed collections of unknown fish into fresh and properly labeled preservation jars. 

Professors and students work together to identify this mystery fish.

In addition to basic morphological features such as fin condition, presence or absence of barbels, tail type and snout shape, it was necessary to count scales to determine finer classifications of unknown specimens.