How to Tell the Difference between Largemouth and Smallmouth Bass

Team Cast & Conquer

How to Tell the Difference between Largemouth and Smallmouth Bass
How to Tell the Difference between Largemouth and Smallmouth Bass

So you want to know how to tell the difference between a largemouth bass and a smallmouth bass?

You’re not alone in wanting that answer because people Google that very same question roughly 1,000 times per month.

Team Cast & Conquer will breakdown the key difference between the two so you’ll never have to ask that question again. Plus, besides their appearances, we’ll let you know the different habitats of largemouth and smallmouth bass so you can have more success when trying to catch them.

Ready? OK, let’s get started!

Largemouth vs. Smallmouth Bass: Physical Characteristics

As their names suggest, the primary difference between smallmouth and largemouth bass are their mouth sizes.

Smallmouth bass have mouths that are appropriately proportioned with their heads, while largemouth bass have oversized mouths and jaws that extend above their eyes and below their bodies.

Here’s a breakdown of the general characteristics between the largemouth and smallmouth bass:

Largemouth Bass Characteristics:

  • Size: Typically about 10-12 pounds on average.

  • Length: Commonly range between 15-22 inches for adults.

  • Coloration: They typically have a greenish to olive-colored body, with a mottled pattern that provides effective camouflage. The belly is usually lighter in color, ranging from white to yellow.

  • Lateral Line: A prominent dark horizontal line, known as the lateral line, runs along each side of the fish. This line helps them detect vibrations in the water.

  • Dorsal Fin: Largemouth bass have two dorsal fins. The first dorsal fin is spiny, while the second is soft-rayed.

  • Mouth: Large mouth that extends beyond the back of the eye. When the mouth is closed, it reaches or covers the eye.

  • Jaw Structure: Upper jaw that extends beyond the eye, distinguishing them from smallmouth bass, whose upper jaw doesn't extend as far.

Smallmouth Bass Characteristics:

  • Size: Typically about 5-7 pounds on average.

  • Length: Commonly in the 12-16 inch range.

  • Coloration: Smallmouth bass typically have a bronze to brownish-green coloration on their back, with a lighter, sometimes bronze, belly. They may also exhibit vertical bars along their sides.

  • Lateral Line: Similar to largemouth bass, smallmouth bass have a lateral line running along each side of their body. This line is sensitive to vibrations in the water.

  • Dorsal Fin: They have two dorsal fins as well. The first dorsal fin is spiny, and the second is soft-rayed. The dorsal fins are usually connected or nearly connected.

  • Mouth: The mouth of a smallmouth bass is smaller than that of a largemouth bass, and it does not extend beyond the back of the eye when closed.

  • Jaw Structure: The upper jaw of a smallmouth bass also does not extend beyond the back of the eye, distinguishing it from largemouth bass.

Largemouth Bass
Largemouth Bass
Smallmouth Bass
Smallmouth Bass

Largemouth vs. Smallmouth Bass: Habitat

Largemouth Bass:

Largemouth bass are adaptable and can be found in various freshwater habitats. Some typical habitats where largemouth bass thrive include:

  • Lakes: Largemouth bass are commonly found in both natural and man-made lakes. They inhabit various zones within lakes, including shallow areas with vegetation, deeper open water, and around structures like submerged rocks and fallen trees.

  • Ponds: Largemouth bass are often stocked in ponds for recreational fishing. Ponds with a mix of vegetation, structure, and suitable water quality provide favorable conditions for their growth.

  • Rivers and Streams: While not as common in fast-flowing waters compared to smallmouth bass, largemouth bass can be found in slower-moving sections of rivers and streams. They prefer areas with cover such as submerged logs, rocks, and vegetation.

  • Reservoirs: Largemouth bass inhabit reservoirs created by damming rivers. They utilize the diverse structures present, including submerged trees, brush, and rocky points.

  • Backwaters and Marshes: Largemouth bass are often found in calm, vegetated backwaters and marshes. These areas provide abundant cover and a variety of prey.

  • Weedy Areas: Largemouth bass are known to seek cover in areas with aquatic vegetation. They use these weedy areas for both ambush hunting and protection.

Smallmouth Bass:

Smallmouth bass have specific habitat preferences that distinguish them from largemouth bass. Some typical habitats for smallmouth bass include:

  • Rivers and Streams: Smallmouth bass are well-adapted to flowing water and are commonly found in rivers and streams. They prefer clear, cool, and well-oxygenated water.

  • Rocky Bottoms: Smallmouth bass are often associated with rocky habitats. They seek out areas with gravel or rocky bottoms, where they can find cover and build nests during the spawning season.

  • Substrate with Current: Smallmouth bass are known for their affinity for areas with moderate to swift current. They are often found near structures such as boulders, rock ledges, and underwater drop-offs.

  • Cooler Water Temperatures: Smallmouth bass tend to thrive in cooler water compared to largemouth bass. They are often found in northern or high-altitude waters where temperatures are lower.

  • Clear Water Lakes: While largemouth bass are more adaptable to various lake habitats, smallmouth bass are often associated with clear-water lakes. They use rocky points, underwater structures, and drop-offs for cover.

  • Gravel Beds: Smallmouth bass commonly spawn on gravel beds. They select areas with suitable substrate for nest-building, typically in shallower sections of rivers or lake shorelines.

  • Coves and Bays: In lakes, smallmouth bass can be found in coves and bays with rocky or gravel bottoms. These areas provide suitable habitat for feeding and shelter.

Largemouth vs. Smallmouth Bass: Best Conditions to Catch Them

Largemouth Bass:

While there's no guaranteed formula for success, understanding the factors influencing largemouth bass activity can put you in the right place at the right time. Here's a breakdown of timing and conditions to consider:

  • Spring: Optimal time, especially during pre-spawn (5 days before and 2 days after full moon) when they're aggressive and near shallows. Water temps ideally in the 50s to low 60s.

  • Summer: Bass seek deeper, cooler water. Early mornings and evenings are best, focusing on deeper structures like ledges and drop-offs. Water temps ideal in the 70s to 80s.

  • Fall: They move back to shallows to feed before winter. Target cover-rich areas like docks and weed beds. Water temps ideal in the 60s to 70s.

  • Winter: Activity slows down considerably. Focus on sunny days with warmer water temps (above 50°F) and fish deep structures during midday.

Time of Day:
  • Dawn and Dusk: Low-light conditions prime their hunting instincts, making them more active and receptive to lures.

  • Night: Can be productive, especially in summer when water is warmer. Full moon nights provide some light for bass to feed.

  • Midday: Less ideal, but overcast and windy days with rippled water can still be good. Avoid harsh sunlight when water is clear.

  • Overcast with light wind: Ideal, as bright sun and calm water make them less active.

  • Rain: Can trigger feeding activity, especially if it stirs up baitfish.

  • Stable barometric pressure: Avoid sudden changes, which can make them sluggish.

  • Water Temperature: Optimal range: 55°F to 85°F. Too cold or too hot, and they become less active.

  • Water clarity: Ideally moderate. Very clear water allows them to see lures from afar and become spooked.

Smallmouth Bass:

Unlike their sun-loving cousins, smallmouth bass thrive in cooler, flowing waters, requiring a slightly different approach when planning your fishing venture. Here's how to optimize your hunt for these feisty fighters:

  • Spring: Pre-spawn (water temps in the mid-40s) is prime, with hungry fish patrolling shallow areas near spawning grounds. Look for rocky beds and current seams.

  • Summer: Early mornings and evenings are key, targeting deeper areas like ledges and drop-offs where they seek cooler water. Water temps ideal in the 60s to low 70s.

  • Fall: Similar to spring, they move back to shallows and structure to feed before winter. Focus on rocky points and current breaks. Water temps ideal in the 50s to 60s.

  • Winter: Activity slows down significantly. Sunny days with warmer water temps (above 50°F) and deep structures during midday are your best bet.

Time of Day:
  • Dawn and Dusk: Similar to largemouth, low-light conditions enhance their feeding activity.

  • Night: Not as effective as for largemouth, but can be productive in deeper, slow-moving sections of rivers.

  • Midday: Less ideal than mornings or evenings, but cloudy or windy days with rippled water can still be good.

  • Cool and overcast: Ideal, as warm, bright sun can make them sluggish.

  • Light rain: Can trigger feeding activity, especially if it stirs up baitfish.

  • Stable barometric pressure: Similar to largemouth, avoid sudden changes.

  • Water Temperature: Optimal range: 45°F to 70°F. They tolerate colder water better than largemouth but become less active in extremes.

  • Water flow: Look for areas with current breaks and eddies where they can ambush prey.


We hope we answered your questions about the differences between smallmouth and largemouth bass.

Just remember to pay close attention to the size of the mouth and how far the jaw extends and you’ll be able to quickly tell if a bass is a largemouth or smallmouth.

Be sure to check out our picks for the best fishing gear so you're ready for your next fishing adventure.