America’s love of fishing encompasses many species, but none are more popular than the largemouth and smallmouth bass.
Widely present, tremendously aggressive, and always up for a hard fight, it’s easy to get addicted to bass fishing, whichever species you prefer.
New anglers may be unsure about the differences between largemouth and smallmouth bass, where you’ll find each, and how to fish for them. That’s OK - there’s always something to learn - and we’re here to help.
We’ll cover everything you need to know, giving you the know-how you need to fish smarter.
Table of Contents (clickable)
Smallmouth vs Largemouth Bass Basics
While the common name “largemouth” is a reference to the huge mandibles of this fish, scientists call it Micropterus salmoides, placing it in the family of black bass. Native to the waters of the eastern and southern US, the largemouth bass’s popularity as a game fish has led to it being introduced pretty much everywhere in the lower 48.
That means that almost wherever you happen to live, there’s great largemouth fishing nearby!
Largemouth bass are aggressive hunters, using their telescoping mandibles to engulf prey items that are far larger than you’d expect. Predominantly sight predators, they thrive in clear water where they can see food at a distance. They then use their sensitive lateral lines and hearing to assess a potential meal, striking with a powerful, engulfing bite when they do.
This largemouth has swallowed a snook nearly as large as it is whole.
Largemouth bass start life as tiny fry, hunting everything from tiny shrimp to insect larvae, but graduating to minnows as they grow larger. At maturity, they’re simply voracious, targeting anything they can find: minnows of all kinds, shad, crawfish, crappie, bluegill, and even other bass, snakes, frogs, birds, bats, and mice.
And while they can be picky eaters in certain seasons - like pre-spawn - they’ll generally feed opportunistically on anything they run across, with a noted preference for soft-finned shad in the summer and fall as they’re both abundant and easy to swallow.
In clear water, where the hunting is especially good, largemouth can reach sizes of 29 ½ inches and official weights near 22 pounds.
Smallmouth bass are named in relation to largemouth, a nod to the fact that their mandibles aren’t nearly as big as their cousins’. Biologists call the smallmouth Micropterus dolomieu, placing it, too, in the family of black bass, and it’s clear that largemouth and smallmouth are related.
Smallmouth bass are native to a wide distribution, originally inhabiting the upper and middle Mississippi River basin, the Saint Lawrence River-Great Lakes system, and the Hudson Bay basin. Popular with anglers for their hard fighting, smallies have been introduced - legally and illegally - over a wide area.
Like largemouth, smallmouth bass are predominantly sight predators, identifying prey items at a distance with their keen eyesight and then moving closer to investigate with their other senses. When they decide to strike, they typically hit hard!
Smallies like the same aquatic prey items as largemouth bass insects, minnows, shad, crawfish, and frogs.
Typically smaller than largemouth, males average about two pounds, while females double or triple that weight. Larger specimens are not uncommon, however, and the current record stands at a whopping 27 inches and 12 pounds!
Smallmouth vs Largemouth Bass Identification - How To Tell The Difference
Largemouth bass wear greenish-gray to olive scales, sporting a distinctive black stripe along their lateral line. Darker on the dorsal (top) portion of their bodies, they fade to a pearlescent white on their ventral (bottom) side.
You can positively identify a largemouth bass by looking closely at its upper jaw. When closed, it will protrude beyond the back of the eye.
You’ll also spot a clearly separated set of dorsal fins divided by a deep “v.”
The first dorsal fin will have 9 to 11 sharp spines. On the posterior dorsal fin, you’ll count 12 to 14 rays.
At first sight, smallmouth bass look a lot like their larger relatives, sporting greenish-yellow scales and a similar body shape to largemouth. But a closer look reveals distinct differences.
First, you’ll notice the absence of a dark lateral line. But there are more determinative clues, too. Look carefully at the upper jaw, and you’ll notice that unlike largemouth, smallies don’t have mouths that run past the rear of the eye.
You’ll also note horizontal bands or stripes running along the head from the snout. And a careful look at its dorsal fins will reveal that they’re connected, making differentiation from largemouth bass simple.
Smallmouth vs Largemouth Bass Habitat, Spawning, and Seasonal Feeding Behavior
It’s always important to remember that largemouth bass are predominantly sight predators, and if you’d like to take a deeper dive into their senses, take a look at these articles:
Largemouth reach their largest sizes in clear water, but they can and do inhabit murky, stained, and muddy areas as well. They prefer little to no current, favoring lakes and ponds to rivers.
They like plenty of aquatic vegetation, giving prey items habitat and themselves a place to hide in potential ambush. Soft bottoms, abundant sunlight, and warm water are magic for largemouth, explaining much of the reason the South enjoys such great bass fishing.
Largemouth bass overwinter in deep holes, where warm water collects due to inversion in cold weather. That may sound strange if you’re a new angler, but in the winter, the warm water is actually on the bottom of the lake, in the deepest portions you can find.
That’s where the bass will be, waiting for warmer weather. They’ll enter a state of cold-induced torpor, slowing down substantially and feeding only sporadically and with little gusto. That doesn’t mean they can’t be caught, but rather that they’ll be hesitant, finicky, and generally less aggressive.
But when spring’s sun starts to warm the water to 55 to 60 degrees, male bass will leave their winter shelter in deep water and move toward the shallows in preparation for the spawn. The females will soon follow. Both sexes begin feeding in earnest to restore their energy, and the females especially will be looking for nutrient-rich prey like crawfish.
During the spawn itself, neither sex will feed actively as their focus will be on reproduction.
A male bass guards his nest.
When the spawn ends, the females will leave the males behind to guard their eggs and fry. And while those males won’t be actively feeding, they will attack anything that comes near the next generation they’re protecting.
Throughout the remaining spring and summer, largemouth bass will feed actively unless pressured by high water temperatures.
In the early fall, bass will be very aggressive as they try to put on weight for the winter. As the water cools, they’ll become less and less active, slowly transitioning back to the depths to wait for spring.
Smallies prefer water that’s crystal clear, and thus they typically prefer rocky bottoms and plenty of current. That doesn’t mean that they don’t inhabit lakes and ponds - they do - but rather that they predominantly make a home in clear rivers and streams.
They’re more cold-tolerant than largemouth but don’t like freezing temperatures. When the water drops to about 60 degrees, they’ll move from the shallows and look for deep holes to overwinter. And just like largemouth bass, they’ll slow down, entering a state of cold-induced torpor.
When the sun warms the water again to 59 to 64 degrees, smallmouth bass will begin transitioning to the shallows again to spawn, engaging in very similar overall behavior patterns when compared to largemouth bass.
This male is in his bed, guarding the fertilized eggs.
The males will move first, followed by the females, and both sexes will be feeding voraciously until the spawn actually begins. Just like largemouth, females will seek out crawfish where they’re available, preferentially feeding on this nutritious and abundant food source.
Post-spawn, the females will move off, feeding actively, while the males guard the eggs until they hatch.
Summer brings active feeding on aquatic insects, amphibians, and minnows, until the water starts to cool again, driving the winter torpor
Whether you fish big lakes for largemouth or clear rivers for smallies, the excitement of hard strikes and tough fights is addictive.
We hope that you’ve learned to tell the difference between these smallmouth and largemouth, identifying them quickly, and you should know where to find them and what to throw to catch them.
As always, we’re here to answer any questions you might have, so please leave a comment below!