Rock Bass vs Smallmouth Bass – What’s The Difference?

Rock bass and smallmouth bass have many similarities. For this reason many people ask about their differences. Let’s answer the question, what is the difference between a rock bass and a smallmouth bass?

Rock bass and smallmouth are different species although from the same family. Rock bass is the A. rupestris species, smallmouth bass is the M. dolomieu species. Smallmouth bass sometimes has a stronger flavor than rock bass. Smallmouth bass contains more mercury and costs more than rock bass.

This article will compare their tastes, textures, cooking methods, costs, mercury levels and whether one can substitute for the other in recipes. In addition, I’ll do a side-by-side comparison of their habitats, size, weight and nutritional values.

Keto Bread Tip: Great News! Did you know, you don’t have to give up your favorite bread, pizza or sandwiches to follow a 100% Keto diet. Find out more in the KetoBreads website by clicking here, Keto Breads.

Disclaimer: The above link and others in this article are affiliate links which means I may earn a small commission at no extra cost to you. As an Amazon associate I earn from qualifying purchases.

Rock Bass vs Smallmouth Bass: Habitats, Size, Weight and Appearance

How can you tell the difference between a rock bass and a smallmouth bass?

The easiest way to tell the difference between a rock bass and a smallmouth bass is the body shape, markings and dorsal fin. Smallmouth bass have a longer slender body compared to the flatter shorter rock bass. Rock bass have one dorsal fin, smallmouth have two dorsal fins. Rock bass have black spotted lateral lines. Smallmouth have brown vertical bars. 

Other ways to tell the difference between a rock bass and a smallmouth bass:

  • Rock bass have teeth inside their mouth and jaw. Smallmouth bass have a round patch of teeth on the tongue.
  • Smallmouth bass have brown horizontal lines or stripes on their head. Rock bass have a dark tear drop shaped marking under their eye but no horizontal lines.
  • Adult rock bass average 6″ to 10″ long. Adult smallmouth average 12″ to 16″ long.

Rock Bass and Smallmouth Bass Scientific Classifications, Families, Species

Rock bass are from:

  • Family: Centrarchidae
  • Genus: Ambloplites
  • Species: A. rupestris
  • Common nicknames: Red eye, rock perch, goggle eye.

Smallmouth bass are from:

  • Family: Centrarchidae
  • Genus: Micropterus
  • Species: M. dolomieu
  • Common nicknames: Brownie, brown bass, brownie, bronze bass, small and bronze back.

Rock Bass and Smallmouth Bass Habitats

Rock Bass

  • Rock bass are native to North America and can be found from Canada down to Florida and west to Texas. They are mostly found in the eastern and central United States.
  • Rock bass are found in streams, ponds, lakes and rivers.
  • Rock bass prefer rocky shorelines and vegetation areas. They can be found under docks and near swimming areas.

Smallmouth Bass

  • Smallmouth bass is native to the upper and middle Mississippi River Basin, the Great Lakes, Saint Lawrence River and the Hudson Bay Basin in Canada. Down south to northern Alabama and eastern Oklahoma. They have been introduced into many cool-water rivers and lakes in the United States and Canada.
  • Smallmouth bass are found in streams, reservoirs, lakes and rivers.
  • Smallmouth bass prefer colder waters and shallow rocky areas of lakes. They like logs and sandy bottoms of reservoirs and lakes.

While both fish can be found up north, the rock bass can be found a little more south than the smallmouth bass.

rock bass and smallmouth bass photo comparison
top Rock bass<br >bottom Smallmouth bass

Rock Bass and Smallmouth Bass Appearance

Rock Bass and Smallmouth Colors

  • Rock bass have an olive green to golden brown upper back and sides fading down to a silvery, white belly. Rock bass have black spots which form broken lateral stripes down the body. The eyes are red.
    • Rock bass have the ability to change colors to match their surroundings for protection.
  • Smallmouth bass have a golden olive to brownish body which fades to a yellowish white near the belly. They have dusky brown blotchy vertical bars or thick stripes down the body. The head has dark brown horizontal bars.
    • Smallmouth have a lighter color in open waters compared to darker when found in darker rivers.

Rock bass has black spotted lateral stripes. The smallmouth bass has brown vertical bars.

Dorsal Fins

  • Rock bass has one dorsal fin with 10-13 spines and 11-13 rays.
  • Smallmouth bass has two dorsal fins separated by a shallow notch. The front dorsal fin has 9-11 spines, and the rear dorsal has 13-15 soft rays.

The rock bass has one dorsal fin with spines and soft rays. The smallmouth bass has two dorsal fins, the front with spines and the second with soft rays.


  • The rock bass mouth is large but doesn’t extend past the eye line. The rock bass mouth doesn’t curve upward.
  • The smallmouth bass jaw doesn’t extend past the eye line. The mouth is protruding and doesn’t curve upward.

Rock bass have teeth inside their mouths. The smallmouth bass has a round patch of teeth on the tongue.

Distinguishing Marks

  • Rock bass has red eyes and rows of dark spots forming lateral lines down the body. Rock bass has a dark tear drop below their eye.
  • Smallmouth bass have either red or brown eyes. The head has dark brown horizontal bars or stripes. The body has dusky brown vertical bars.

Rock bass have red or orange eyes compared to smallmouth’s red or brown eyes.

Body Shape

  • The rock bass body is flat is slightly elongated.
  • The smallmouth body have a slender, fusiform body shape.

The smallmouth’s body is slender and longer than the rock bass.

Rock Bass and Smallmouth Bass Size and Weight

  • Rock bass average 6-10″ long and weighs about 1 pound.
  • Smallmouth bass average 12-16″ long and weighs 2-6 pounds.

Smallmouth bass on average weigh more and are longer than rock bass. Smallmouth females weigh more than the males.

Rock Bass and Smallmouth Bass Lifespan

  • Rock bass lives up to 8-10 years.
  • Smallmouth bass lives up to 7 years.


Rock bass consume the following:

  • Insects
  • Worms
  • Smaller fish
  • Minnows
  • Small crustaceans

Smallmouth bass consume the following:

  • Plankton
  • Insects
  • Small fish
  • Crayfish

Species Resources 1 2 3 4 5 6 7 8 9

In a recent article I compared rock bass to crappie. Find out how these similar sunfish compared in my article, Rock Bass vs Crappie – What’s The Difference? Let’s Compare.

smallmouth bass and rock bass photo
top Smallmouth bass<br >bottom Rock bass

Rock Bass and Smallmouth Bass: Tastes and Textures

One of the most important things people takes into consideration when choosing a fish is its taste. When comparing the two fish, does rock bass taste like smallmouth bass?

Rock bass and smallmouth bass have a similar mild to sweet taste. Smallmouth bass may have a stronger flavor depending on the water it was caught in. Rock bass and smallmouth bass have a firm texture and a little flakey. 

What does smallmouth bass taste like? Smallmouth bass has a mild to sweet taste. Depending on the water it was caught in, it may have a slight fishy flavor. The white flesh has a firm texture.

Is rock bass fish good to eat? Rock bass is good to eat. Most people are pleased with the mild taste. The flesh is slightly firm and flakey.

I polled many of my readers and members of food groups I belong to. The following are the results of my poll which consisted of 30 people. I asked which fish tasted better, smallmouth or rock bass?

  • 35% preferred the taste of rock bass.
  • 45% preferred the taste of smallmouth.
  • 20% said they liked both fish the same.

Bluegill is another popular sunfish like rock bass. Check out in my recent article which one tasted better in my poll of my readers, Rock Bass vs Bluegill – What’s The Difference? We Compare.

Rock Bass and Smallmouth Bass Substitutions

When preparing recipes for dinner it’s not always possible to locate the type of fish called for. If you have some rock bass or smallmouth bass, you may ask, can I substitute smallmouth bass for rock bass?

Smallmouth bass can substitute for rock bass due to their similar mild to sweet tastes. Rock bass and smallmouth have a firm texture allowing them to be used in many of the same recipes and cooking methods. They both can be cooked using similar methods like baking, broiling, steaming and frying. 

One thing to remember when choosing between rock bass and smallmouth bass is the size of the fillet. The smallmouth bass fillet is larger or is easier to fillet if you have a whole fish.

Rock bass substitutes:

  • Bluegill
  • White crappie
  • Black crappie
  • Pumpkinseed
  • Green sunfish
  • Lake herring
  • Tilapia
  • Pollock

Smallmouth bass substitutes include the following:

  • Freshwater trout
  • Lake herring
  • Mackerel
  • Snapper
  • Grouper
  • Halibut

How To Cook Rock Bass

Popular ways to cook rock bass are:

  • Deep frying
  • Pan frying/stir fry
  • Baking
  • Grilling

Flavor pairings for rock bass:

  • Cayenne pepper
  • Black pepper
  • Cajun
  • Tarter sauce
  • Beer batter
  • Bread crumbs
  • Crackers
  • Parmesan cheese
  • Lemon juice
  • Brown sugar

How To Cook Smallmouth Bass

Smallmouth bass doesn’t have the same fishy flavor and smell that a largemouth contains. Therefore, smallmouth bass doesn’t have to be seasoned as much to cover up the fishiness.

Smallmouth can be grilled, pan fried, baked, broiled and sautéed.

Smallmouth flavor pairings:

  • Garlic
  • Lemon
  • Dill
  • Mustard
  • Black pepper
  • Parsley
  • Olive oil

Find out if smallmouth bass can substitute for largemouth bass in my article, Smallmouth Bass vs Largemouth Bass: What’s The Difference? Also, find out if their mouths really different?

How Much Rock Bass and Smallmouth Bass Costs

The costs for fresh fish will vary depending on how the fish are caught. When purchasing any fish, be sure to check the label to see if it is wild-caught or farm raised. Therefore, which is more expensive, rock bass or smallmouth bass?

Smallmouth bass is more expensive than rock bass. The average cost for sunfish fillets is $16 to $22 per pound. Live smallmouth bass cost $8.99 per 3-4″ fish. The average live sunfish averages $0.75 to $1 per 3-4″ fish. 

I checked online at Walleye Direct and found the following prices:

  • Wild, crappie fillets (sunfish)
    • $22.00 per pound

Seafood Markets:

  • Wild, sunfish fillets (does not specify which kind of sunfish)
    • $18.00 per pound

Dixon Fisheries:

  • Bluegill fillets (sunfish)
    • $14.95 per pound

For stocking ponds, Pond King has the following price per fish:

  • Black crappie – $1.00 per 3-4″ fish
  • Bluegill – $0.75 per 3-4″ fish
  • Hybrid bluegill (green sunfish x bluegill) $0.75 per 3-4″ fish
  • Largemouth bass – $1.25 per 2-3″ fish
  • Smallmouth bass – $8.99 per 3-4″ fish

Rock Bass and Smallmouth Bass Mercury Levels

The EPA and The FDA have issued suggestions and warnings about mercury levels in fish and how often they should be consumed 10. This is especially important for young infants, pregnant women and developing children.

They established three lists:

  1. Best fish
  2. Good choices
  3. Ones to avoid

Therefore, does rock bass or smallmouth bass have more mercury?

Smallmouth bass have more mercury than rock bass. Freshwater bass has been listed on some states advisory warnings for high levels of mercury. Rock bass is one of the FDA’s best choice of fish regarding mercury levels.

If you’re pregnant, breast feeding or has a young child, Always check with a physician prior to eating new foods or changing your dietary habits.

These mercury warnings can change over time or affect only a particular area or state. Please check with your local EPA and FDA for the current recommendations 11.

Rock Bass and Smallmouth Bass Nutritional Values

Rock bass and smallmouth bass are excellent sources of protein, healthy fats, minerals and B vitamins. Both sunfish fish contain the following:

  • Omega-3 fatty acids
  • Magnesium
  • Potassium
  • Folate
  • Niacin
  • B6
  • B12
  • B5
  • Thiamin
  • Riboflavin
  • Iron
  • Selenium
  • Calcium
  • Zinc

Fresh water bass provides the following number of nutrients per four raw ounces:

Nutrient Freshwater bass
(4 ounces, raw)
Calories 129
Fat 4.2 g
Saturated fat 0.9 g
Cholesterol 77 mg
Protein 21 g
Omega-3 0.77 g
B-6 0.1 mg
B-12 2.2 mcg
Thiamin .08 mg
Riboflavin .08 mg
B-5 0.8 mg
Niacin 1.4 mg
Folate 17.0 mcg
Iron 1.6 mg
Potassium 403 mg
Magnesium 34 mg
Phosphorus 226 mg
Calcium 90.7 mg
Zinc 0.7 mg
Selenium 14.2 mcg

Nutrient Resources 12 13 14 15

Rock bass and smallmouth provide a similar percentage of the same nutrients, except for omega-3 fatty acids. Freshwater bass provides 0.77 g while most smaller sunfish, like rock bass, provide approximately 0.16-0.29 g per 4 ounces.

Keep reading the next section below to find out how the nutrients benefit health, especially omega-3s.

Rock bass, smallmouth bass and other fish are renowned for being a part of many diets like keto or heart healthy.

If you’re eating low-carb or want to give keto a try, many of my clients have followed this 28-Day Keto Challenge with great success. Visit their website and check it out.

In this article I compared smallmouth to spotted bass. Find out their differences, Spotted Bass vs Smallmouth Bass: What’s The Difference?

Rock Bass and Smallmouth Bass Health Benefits

Omega 3 Fatty Acids

The omega-3 fatty acids contained in smallmouth bass and rock bass help keep arteries healthy and are considered heart healthy. The omega-3s may help with the following:

  • Lowering triglycerides.
  • Reduce inflammation.
  • Reduce plaque buildup.
  • Keeping bad cholesterol low.
  • Keeping good cholesterol high.
  • Help keep the heart rhythms more normal.

DHA and EPA, two of the fatty acids, are associated with lowering blood pressure and improving the health of blood vessels 16.

Studies suggest omega-3s can help reduce joint pain and stiffness in people with rheumatoid arthritis. They may also boost the effectiveness of anti-inflammatory drugs.


Potassium provided by smallmouth bass and rock bass is approximately 357-400 mg. Potassium helps the body get rid of excess sodium which helps reduce fluid build-up. These help keep systolic and diastolic blood pressure lower 17.

The more potassium you consume, the more sodium your body will lose. Consuming too much sodium or not enough potassium throws off the delicate balance the kidneys need to remove the excess water 18.

According to Harvard Health, a number of studies have shown a connection between low potassium levels and increased blood pressure 19.


Smallmouth bass and rock bass provide 85-90 mg of calcium per four ounces. Calcium is important for blood pressure and the heart. Harvard Health reports calcium helps maintain blood pressure because it helps to control the relaxing and tightening of blood vessels 20.

Calcium also helps the following:

  • Build and maintain strong bones.
  • Muscles need calcium to function properly.
  • Improve nerve function.

B Vitamins

The B vitamins provided by smallmouth bass and rock bass include B1 (thiamin), B2 (riboflavin), B3 (niacin), B9 (folate) B6, B12 and B5. B vitamins help support the following:

  • Digestion.
  • Brain function.
  • Energy levels.
  • Red blood cells.
  • Cardiovascular disease.
  • Nerve function.


Smallmouth bass and rock bass provide about 34-39 mg of magnesium per four ounces. It calms and relaxes the whole body including blood vessels. Magnesium has been shown to help improve sleep related problems like insomnia 21.

Magnesium helps keep blood pressure levels balanced and stable. A recent study researched 22 studies and concluded magnesium supplementation decreased diastolic and systolic blood pressure 22.

Magnesium helps control muscle and nerve function, blood sugar and blood pressure.

In the muscles and heart, magnesium competes with calcium to help the muscles relax after contracting. When the body is low in magnesium, calcium can over stimulate the heart muscle’s cells causing a rapid or irregular heartbeat.


There are 13-14.2 mcg of selenium per four ounces of smallmouth bass and rock bass. Studies 23 show selenium may help to protect the following:

  • The immune system
  • Thyroid
  • Cognitive issues
  • Heart disease


Smallmouth bass and rock bass provide approximately 203-259 mg of phosphorus per four ounces. It has been shown in scientific research to help with the following:

  • Promote healthy nerve conduction.
  • Aides the kidneys in waste removal.
  • Promote teeth and bone strength.
  • Muscle recovery after exercise.
  • Muscle contraction.
  • Help the body store and manage energy.

Read Next – More SunFish vs SunFish Articles!

Bluegill vs Redear Sunfish – Are They The Same? We Compare

Black Crappie vs White Crappie – What’s The Difference?

Bluegill vs Pumpkinseed – Are They The Same? Let’s Compare

Bluegill vs Redbreast Sunfish – What’s The Difference?

Article Resources: Foods For Anti-Aging follows strict guidelines to ensure our content is the highest journalistic standard. It's our mission to provide the reader with accurate, honest and unbiased guidance. Our content relies on medical associations, research institutions, government agencies and study resources. Learn more by reading our editorial policy.
  1. Wikipedia: Rock bass[]
  2. Rock Bass[]
  3. USFWS National Digital Library: Rock bass[]
  4. Minnesota Department of Natural Resources: Rock bass[]
  5. West Virginia Department of Natural Resources: Rock Bass[]
  6. Minnesota Department of Natural Resources: Sunfish biology and identification[]
  7. The Department of Natural Resources: Sunfish[]
  8. Wikipedia: Smallmouth bass[]
  9. Chesapeake Bay Program: Smallmouth Bass[]
  10. FDA: Advice about Eating Fish[]
  11. National Center for Biotechnology Information: Mercury accumulation in largemouth bass (Micropterus salmoides) in a Florida lake[]
  12. Nutrition Value: Fish, raw, mixed species, fresh water, bass[]
  13. NutritionData: Fish, bass, fresh water, mixed species, raw[]
  14. The Topeka Capital-Journal: Keto, Paleo or Atkins diet? Hunting, fishing can help trim your waistline in 2020[]
  15. Nutritiondata: Fish, sunfish, raw[]
  16. National Center for Biotechnology: Marine Omega-3 Supplementation and Cardiovascular Disease[]
  17. American Heart Association: How Potassium Can Help Control High Blood Pressure[]
  18. National Center for Biotechnology Information: The Effect of the Sodium to Potassium Ratio on Hypertension Prevalence: A Propensity Score Matching Approach[]
  19. Harvard Health: Potassium lowers blood pressure[]
  20. Harvard Health: Key minerals to help control blood pressure[]
  21. National Institutes of Health: Magnesium[]
  22. National Center for Biotechnology Information: Effect of magnesium supplementation on blood pressure: a meta-analysis[]
  23. National Institutes of Health: Selenium[]

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