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?

Smallmouth bass and rock bass 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 both bass 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.

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

How can you tell the difference between the two?

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.

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

Other ways to tell the difference:

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.

Bass Habitats

Rock

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.
They can be found fishing in streams, ponds, lakes and rivers.
They prefer rocky shorelines and vegetation areas. They can be found under docks and near swimming areas.

Smallmouth

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.
They can be found fishing in streams, reservoirs, lakes and rivers.
They prefer colder waters and shallow rocky areas of lakes. They like logs and sandy bottoms of reservoirs and lakes.

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

Appearance

Colors

Rock have an olive green to golden brown upper back and sides fading down to a silvery, white belly. They have black spots which form broken lateral stripes down the body. The have red eyes.
- They 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. The bass have dusky brown blotchy vertical bars or thick stripes down the body. The head has dark brown horizontal bars.
- They have a lighter color in open waters compared to darker when found in darker rivers.

Video explaining differences between largemouth and smallmouth bass.

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.

Anal Fins

The rock anal fin has 5-7 spines followed by soft rays.
The smallmouth anal fin has 3 spines.

Mouth

The rock 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.

Body Shape

The smallmouth’s fusiform body is slender and longer. Rock bass are more rounded tall and flatter.
The big difference is rockbass are shaped like a sunfish.

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.

Lifespan

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

Diet

Rock bass consume the following:

Insects
Worms
Smaller fish
Minnows
Small crustaceans

Smallmouth bass consume the following:

Plankton
Insects
Small fish
Crayfish

In a recent article I compared crappie. Find out how these similar sunfish compared to bass in my comparison article..

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

Fishing

Rock bass fishing won’t win many popularity contests amongst anglers. Despite their gamefish appeal, when fishing they are strangely appealing.

They can get caught with almost any angling method. Live bait works extremely well. Bass fishing within a few feet of the bank is best.

Tastes and Textures

One of the most important things people takes into consideration when choosing any food is its taste. When comparing the two, what do they taste like?

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. They both have a firm texture and a little flakey.

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

To conduct original research, I polled many of my readers, clients 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?

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

To conduct more research, I set up a taste test at home. When both were purchased I cooked each fish the same way. The results were a little different than my poll due to the fishier taste of the smallmouth.

Bluegill is another popular sunfish. Check it out and bass in my recent article and find out which one tasted better in my poll of my readers.

Underwater smallmouth video and fishing footage.

Substitutions

When preparing recipes for dinner it’s not always possible to locate the type of food called for. If you have only one or caught just one type fishing, you may ask, can I substitute one for the other?

Smallmouth bass can substitute for rock bass due to their similar mild to sweet tastes. Both of them 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 the two bass is the size of the fillet. The smallmouth 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

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

The bass can be grilled, pan fried, baked, broiled and sautéed.

Find out if it can substitute for largemouth bass in my comparison article here. Also, find out if their mouths really different?

How to cook a smallmouth bass.

Costs

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

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.

To conduct more research, I checked online for the prices of each bass.

Walleye Direct:

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 – $8.99 per 3-4″ fish

Kevin Garce checking prices of catfish and seafood in his local supermarket. — Checking prices of catfish bass and seafood in my local market

Mercury Levels

The EPA and The FDA have issued suggestions and warnings about mercury levels in fish and how often they should be consumed¹. This is especially important for young infants, pregnant women and developing children.

They established three lists:

Best fish
Good choices
Ones to avoid

Therefore, which one has 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 recommendations².

Nutrition Values

Both basses 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 ((Nutrition Value: Fish, raw, mixed species, fresh water, bass))³ ((The Topeka Capital-Journal: Keto, Paleo or Atkins diet? Hunting, fishing can help trim your waistline in 2020))⁴

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

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

Since the bass are difficult to locate in stores, I’ll consume either fish available to me for their nutrient content and health benefits.

In this article I compared smallmouth to spotted bass. Find out their differences, Spotted 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 ((National Center for Biotechnology: Marine Omega-3 Supplementation and Cardiovascular Disease)).

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

Potassium provided by both 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 ((American Heart Association: How Potassium Can Help Control High Blood Pressure)).

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 water⁵.

According to Harvard Health, a number of studies have shown a connection between low potassium levels and increased blood pressure⁶.

Calcium

Both 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 vessels⁷.

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 the two 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.

Magnesium

Both 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 ((National Institutes of Health: Magnesium)).

Magnesium helps keep blood pressure levels balanced and stable. A recent study researched 22 studies and concluded magnesium supplementation decreased diastolic and systolic blood pressure⁸.

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.

Selenium

There are 13-14.2 mcg of selenium per four ounces of the two bass. Studies⁹ show selenium may help to protect the following:

The immune system
Thyroid
Cognitive issues
Heart disease

Phosphorus

Both 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.

Comment or Reply

If you have any questions about this article don’t hesitate to email us and comment. You can find an email on our contact page.

As a Certified Health Coach many of my clients ask me about seafood. In addition to educating my Health Coaching clients about smallmouth and rock bass, I have researched, purchased and consumed both fish for 20 years prior to, during and after writing this article.