How to Identify a Largemouth Bass (Micropterus salmoides)

• Body shape: Bodies are generally shaped like a laterally flattened football.
• Jaw length: The jaw extends well behind the back margin of the eye when the mouth is closed.
• Dorsal fin: The spiny and soft dorsal fins are almost completely separated.
• Body markings: A dark-green back with a white-to-grayish-white belly and a dark black lateral stripe running from the gill plate to the tail.
• Tongue: Largemouth bass have no tooth patch on the tongue.

The largemouth's jaw extends well behind the rear margin of the eye when the mouth is closed; the smallmouth's upper jaw does not extend past the rear margin of the eye. See the Smallmouth Bass page for its full mark list.

Largemouth bass have no tooth patch on the tongue, while spotted bass have a rough tooth patch at the center of the tongue. See the Spotted Bass page for its full mark list.

A freshwater fish that prefers warm, slow-moving streams, backwaters of large rivers, natural lakes, and impoundments of all sizes. Originally found from southeastern Canada through the Great Lakes, south down the Mississippi Valley to Mexico and Florida, and up the Atlantic coast as far north as southern Maryland.

Lay the fish flat on its side in even light and photograph the whole body first, then the details below. Get a close, sharp frame of the head: mouth, jaw length and any barbels. Raise the dorsal and anal fins fully; ray counts and fin edges only read when the fin is spread. Shoot the side of the body before the fish dries; spots and stripes fade fast out of water. The app reads the photo and names the likely species; use the marks on this page to confirm it.

Size and daily limits for this species differ by state and by water, and some waters are catch-and-release only. Check the current regulations for where you are fishing before keeping any fish; if you are unsure of the species, release it.