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Who You Calling Big Mouth? Our Bass Explained

Updated: Nov 1, 2023

Bass are popular catches for anglers. They put up an exciting fight on the fishing line and taste good too. You hear about largemouth and smallmouth bass. But what’s in a name? People might use “big mouth” as an insult for someone who speaks loudly or gossips and says things they shouldn’t. With bass, mouth size is just a description of, well, the size of their mouth.

A largemouth bass with its mouth open being held up by a hand.
A largemouth bass. (Photo via Shutterstock)

Is mouth size the only difference between largemouth and smallmouth bass? Nope, it just happens to be the feature those who named the fish decided on. After reading all the differences maybe you’ll think of a better name!


Largemouth bass do have a larger mouth than smallmouth bass. Their jaws extend past their eyes. They can open their mouths wider and eat bigger bait.

Can you see the difference in mouth size? (Graphic via Shutterstock)

The jaw of smallmouth bass only extends to the middle of their eyes. It may not be as big, but that doesn’t keep it from catching enough prey to stay full.

Largemouth bass don’t just have bigger mouths. They have bigger everything! They can grow up to 2 times larger than smallmouth bass. Body size isn’t the best indicator of who’s who, though. Fish grow as they age, just like humans. So unless you get an invitation to a the bass’ birthday parties, you won’t know if the largemouth and smallmouth in question are the same age!


Congratulations! You caught a bass! Would you call the scales greenish or brownish? Largemouth bass usually look greenish, while smallmouth bass look brownish.

Both display stripes. Look for a long, horizontal (side to side) stripe running from eye to tail on largemouth bass. Smallmouth bass have the opposite. Many vertical (up and down) stripes mark them from gills to tail.


Fish have several fins. You only need to check out the dorsal fin along its back to tell the difference between these fish, though. The dorsal fin on a largemouth bass has a break in the middle, making it look like two fins. A smallmouth’s dorsal fin has a dip in the middle, like a ramp at a skate park, but still looks connected.


Words to know

Ambush: A surprise attack by something or someone in a concealed position.

Angler: A person who fishes with a rod and line.

Dorsal: Relating to the upper side of an animal, plant or organ.

Murky: Dark and dirty.


Now you know some differences. Do you think largemouth and smallmouth bass are the best names, or would you pick something else? Maybe ditch pickle, bronze back or bucket mouth? These are a few common but silly bass nicknames. Do you want to try fishing for one or the other? Let’s find out where to go.

Bass are freshwater fish, so take your pole and bait to rivers or lakes. They live in almost every state in the U.S., including Illinois. Though both can be found in the same body of water, their favorite parts to hang out and hunt differ.


Largemouth bass prefer warmer water. Mid-70s to mid-80s degrees is ideal, which is about the same temperature as an unheated outdoor pool in the summer.

A largemouth bass swimming in murky water.
A largemouth bass. (Photo via Shutterstock)

Unlike a clean, clear swimming pool, though, largemouth bass like murky water with lots of vegetation for hiding. This suits their ambush style of hunting. They stay still and out of sight waiting for prey to swim past.

Smallmouth bass get in on the action. Not content to wait for prey, they actively hunt. Clear, faster moving water is perfect for this because it helps them see prey and chase it down. This water tends to be cooler, closer to 60 degrees to 70 degrees, or about the same average temperature inside most homes.

Want to try your hand at fishing? Many preserves have fishing opportunities. Don’t have the right gear? Borrow free fishing poles at Monee Reservoir and Hidden Lakes Trout Farm at Hidden Oaks Preserve. Just bring or buy your own bait and fishing license and enjoy a day on the water.


Follow Willy's Wilderness on Facebook for more kid-friendly nature stories and activities.


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