There are Plenty of Fish in the Mississippi

Figure 1: Alligator Gar

Figure 1: Alligator Gar at the Tennessee Aquarium. Photo courtesy of the Tennessee Aquarium.

If you live near the Mississippi River, you surely know of catfish. Blues, Channels and Flatheads are all well-known and well-loved, but there are many fish in the river that are just as awesome. One group of fish that is under appreciated is Gar.

Gars are incredible fish. Most fishermen will call them nuisances, but they are important predators in the river ecosystem and are only found in North and Central America. In the Mississippi/Midwest, we have four species: Spotted, Shortnose, Longnose and Alligator. They are members of an ancient group of fish and have long, toothy beaks, slender bodies and diamond-shaped, armor-like scales1.

Alligator Gars (See Figure 1) are the most famous but are uncommon around Illinois. They are found mostly in the far southern swamps of the U.S. Alligator Gar are the biggest species and can reach a length of 6-10 feet long.

Figure 2: Longnose Gar

Figure 2: Longnose Gar. Photo courtesy of Newport Aquarium

The other three are more common in our area. The Spotted reaches a length of 33-44 inches, and the Longnose (See Figure 2) grows 36-72 inches long, while the Shortnose reaches 24-33 inches1,2. Length often depends on environment. Lakes and low flow areas can help grow larger fish.

Figure 3: Bowfin and Bowfin skull

Figure 3: Bowfin and Bowfin skull. Photos courtesy of and

Another cool fish is the Bowfin (See Figure 3). They are the only living species of an otherwise extinct group of fish. They look prehistoric and are ferocious predators. Bowfins are well-armored and have a round, blunt head, a long dorsal fin, and a rounded tail. They can be found throughout the Mississippi River basin in river backwaters, lakes and swamps1. As you can probably guess, both Gars and Bowfins eat other fish. What else would all those teeth be for?

Figure 4: Paddlefish

Figure 4: Paddlefish. Photos courtesy of Ichthyologist and Tulsa World.

The Paddlefish (See Figure 4) is a well-loved species, and I bet you can guess how it got its name. Contrary to popular belief, these fish are not a kind of catfish. They are survivors of another ancient group of fish, and their appearance makes them hard to mistake. They have a very long paddle-like snout and smooth skin and can grow 36-48 inches long1,2. Paddlefish are highly migratory and live in large rivers, lakes and bayous. These fish swim with their large mouths open, moving their head and snout side to side to filter out plankton to eat1. The paddlefish has an incredible history, but that is a subject of a future post. So be sure to check back in.

Figure 5: Least Brook and the invasive Sea Lamprey

Figure 5: Least Brook and the invasive Sea Lamprey. Photos courtesy of the ODNR Division of Wildlife and Ontario’s Invading Species Awareness Program

Now let’s talk about Lampreys (See Figure 5). They are both cool and creepy at the same time. They are another ancient lineage and predate bony fish. They are yet another ancient lineage of fish that predates bony fish. They do not have bones but a skeleton of cartilage instead, and they have a simple organ system. Young lampreys feed on plankton by filtering it out of the water. After several years, they metamorphose into adults.

Some lamprey species are parasites and feed by attaching themselves to other fish when they mature, but other species will mate and die without feeding1. There are a total of 38 species around the world, and 19 of those occur in the fresh waters of North America2. Although this may sound horrid, our fish evolved with our native lampreys. Their feeding has little effect on fish populations. However, the Sea lamprey in Lake Michigan is invasive and is believed to be at least in part responsible for the decline in fish populations there.

There are seven lamprey species living in the Illinois region including the Sea Lamprey (See Figure 5). The natives include the Ohio, Chestnut, Northern Brook, Silver, Least Brook (See Figure 5), and the American Brook1. These only get between 6-14 inches depending on species. The Sea Lamprey reaches a length of 20 inches1.

Figure 6: American Eel

Figure 6: American Eel. Photo courtesy of the Chesapeake Bay Program

The American Eel (See Figure 6) is our final fantastic fish for the day. They are what is known as Catadromous. This means that they live in fresh water and migrate to salt water to breed. It is the exact opposite of salmon. If you catch an eel far up in a river, you have caught a female. Only females migrate far into fresh water, and they will spend many years feeding and growing before reaching reproductive age. When females are ready to breed, they release a pheromone into the water. It precedes them down the river and tells the males waiting in the delta that females are on the way so they can get ready for mating. Cool huh? There is so much more I could say about eels, but I think I’ll save that for another post.

There are many amazing fish in our great Mississippi, and I have left plenty of room for you to explore this subject more. Click here to learn more.

Come back on November 6 to learn about some incredible research being done by the Illinois Natural History Survey on Shovelnose Sturgeons.

  1. Smith, P.W. 2002. The Fishes of Illinois. The Univ. of Illinois Press., Urbana and Chicago., IL.
  2. Page, L.M. and Burr, B.M. 1991. Freshwater Fishes. Houghton Mifflin Company., New York.
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