Saltwater Fish Identifier: How to ID Your Catch

Official ID guides separate look-alike fish with a handful of body features rather than color alone, because color changes with depth, age and time out of the water. The Washington eRegulations guide shows how much each one tells you:

• How many fins on the back. Lingcod has a single long dorsal fin with only one notch; Pacific cod and walleye pollock have three; cabezon has two.
• A whisker (barbel) under the chin. Pacific cod has a large one; walleye pollock's is absent or very small. That single feature separates two brown, mottled, three-finned fish.
• Which side the eyes are on. Among flatfish, halibut and rock sole are right-eyed, and sanddabs are left-eyed. Rock sole also has a lateral line that arches above the pectoral fin.
• Tail and fin shape. Sanddabs have a squared tail; halibut shows three points on the tail; Pacific hake's second dorsal fin is deeply notched.
• Mouth, skin and gills. Hake is black inside the mouth, cabezon has a skin flap between the nostrils, and the sixgill shark has six gill slits on each side.

Florida's Fish and Wildlife Conservation Commission (FWC) publishes an illustrated Reef Fish Identification guide organized by family: 13 snappers (among them red, vermilion, lane, yellowtail, mutton and gray or mangrove snapper), groupers and sea basses (including gag, black, red, scamp, goliath and Nassau grouper), jacks such as greater amberjack and almaco jack, and other reef fish such as grunts, porgies, triggerfish and hogfish. Each drawing links to a species profile.

For the most-asked snapper, NOAA Fisheries gives these features: red skin and red eyes, a long triangular face that slopes more steeply on top, enlarged canine teeth, and a size of up to 40 inches and 50 pounds. Fish from deeper water tend to be redder. In U.S. waters red snapper are found from North Carolina to Texas and are rare north of the Carolinas.

It depends on the coast, which is why state agencies publish their own guides. From the three official guides above:

• Pacific Northwest (Washington): lingcod, Pacific cod, walleye pollock, kelp greenling, cabezon, Pacific hake, halibut, rock sole, sanddabs and sixgill shark.
• Southeast and Gulf (Florida): snappers such as red, gray (mangrove), yellowtail and vermilion; groupers such as gag, red and black; greater amberjack; grunts, porgies, triggerfish and hogfish.
• Mid-Atlantic (North Carolina): the Division of Marine Fisheries splits more than 40 profiles into inshore/coastal and offshore fish, and notes that offshore species sometimes come closer to shore.

Kelp greenling is a good example of why one photo is not always enough: the Washington guide lists the sexes separately because they look different. It describes females with small reddish-brown to golden spots and yellowish-orange fins, and males with irregular blue spots on the front half of the body.

Seasons, size limits and bag limits are set species by species, so two similar snappers or groupers can have different rules on the same day. The Fish Rules app pairs identification photos (swipe an image for ID clues) with regulations filtered by your phone's GPS and calendar, for federal and state saltwater from Maine to Texas to Hawaii. If you are unsure of the species, check before you keep the fish.

Yes, as a starting point. Google describes Lens as a way to search with your camera or an image and to find out what plant or animal you are looking at; it works in the Google app, Google Camera, Google Photos and Chrome. Fish Rules is built for anglers and adds the regulations. NatureLens identifies fish along with plants, birds and other wildlife, with free scans every day.

Our advice for any app: treat the answer as a candidate and confirm it with the fin, whisker and eye-side checks above, or send the photo to your state agency. North Carolina, for example, asks anglers to email a photo, a description and the catch location to NCFishIDHelp@ncdenr.gov.

Our checklist, built around the features official guides use:

• Lay the fish flat on its side, head to the left, on a wet surface; spread the dorsal fins so you can count them
• Take one close-up of the head showing the mouth, chin and eyes, and one of the tail
• For a flatfish, photograph the top side so it is clear which way the eyes face
• Put a tape measure or ruler along the body
• If you are releasing the fish, keep it wet and the photo session short

Research and drafting for this page used AI assistance. Every number, date and claim was then checked against the sources listed below, which were opened and read on 2026-09-25. Where a statement is our own advice rather than a sourced fact, the text says so.