Types of Seafood - seafoodsguide.com

Types of seafood including fish and shellfish

Types of Seafood: A Complete Guide to Fish, Shellfish & Ocean Delicacies

Introduction

Standing at the seafood counter, most shoppers face the same problem. Rows of fish, shrimp, crab, and mussels all look similar, yet they belong to completely different categories with different tastes, textures, and health benefits. Understanding the types of seafood makes shopping, cooking, and eating out far less confusing. Seafood is a broad term for edible aquatic animals harvested from oceans, rivers, and lakes. It splits into two major groups: finfish, which includes species like salmon and tuna, and shellfish, which covers crustaceans such as shrimp and crab along with mollusks like clams and oysters. Some categories also include less common options like seaweed and roe.

This guide breaks down each major category in plain language, explains how professionals classify seafood, and highlights the nutritional differences that matter most. By the end, readers will know exactly what separates a crustacean from a mollusk, which types of seafood offer the most protein, and how to pick fresh options with confidence.

What Is Seafood?

Seafood refers to any edible aquatic animal harvested from saltwater or freshwater environments. This includes fish, crustaceans, mollusks, and certain other marine organisms that humans have eaten for thousands of years. Some definitions also extend to edible sea plants like seaweed, though the core meaning centers on animal life pulled from oceans, rivers, and lakes.

The term covers two broad origins:

Saltwater seafood, sourced from oceans and seas, including tuna, salmon, and lobster
Freshwater seafood, sourced from rivers and lakes, including catfish, trout, and crawfish

Main Categories of Seafood

Understanding seafood becomes simple once you divide it into just 2 major categories: Fish and Shellfish. These two categories differ significantly from one another in terms of body structure, habitat, and nutritional profile.

Fish are aquatic animals that have a backbone (spine), gills for breathing, and fins for swimming. They are found in both freshwater (rivers, lakes) and saltwater (oceans, seas) environments. Examples: salmon, tuna, cod, and trout.

Shellfish are aquatic animals that do not have a backbone, but instead have an exterior shell or exoskeleton that protects their soft body. Shellfish are further divided into 2 sub-groups:

Crustaceans, which have a hard exoskeleton, such as shrimp, crab, and lobster
Mollusks, which have soft bodies, either with or without a shell, such as oysters, clams, squid, and octopus

Types of seafood divided into fish and shellfish

Types of Fish

Saltwater Finfish

Salmon – rich, oily fish high in omega-3s, popular grilled or raw
Tuna – firm texture, used in sushi, steaks, and canned products
Cod – mild, flaky white fish, common in fried dishes and fish and chips
Halibut – lean, firm white fish, often grilled or baked
Mackerel – small oily fish with a strong flavor, rich in omega-3s
Sardines – tiny oily fish, often canned, nutrient dense
Anchovies – small, intensely flavored fish used in sauces and as a seasoning
Snapper – mild, slightly sweet white fish, popular in Southern US and Caribbean cooking
Sea bass – delicate, buttery texture, common in fine dining
Flounder – thin, mild flatfish, quick cooking
Herring – oily fish often smoked, pickled, or cured
Swordfish – meaty, steak-like texture, ideal for grilling
Mahi mahi – firm, mild fish popular in tacos and grilling
Grouper – firm white fish with a mild, sweet flavor
Haddock – similar to cod, mild and flaky
Pollock – mild white fish, often used in fish sticks and imitation crab
Sole – delicate flatfish, light flavor
Mullet – firm, slightly oily fish common in Southern US cuisine
Monkfish – firm, lobster-like texture, sometimes called “poor man’s lobster”
Bluefish – oily, strong-flavored fish popular on the East Coast

Freshwater Finfish

Tilapia – mild, affordable, widely farmed
Catfish – mild flavor, popular fried in Southern US cuisine
Trout – delicate flavor, similar to salmon but milder
Bass – includes largemouth, smallmouth, and striped bass, firm and mild
Carp – firm texture, common in Asian and Eastern European cuisine
Perch – small, mild, flaky freshwater fish
Pike – lean, firm fish with a slightly gamey flavor
Walleye – mild, flaky, popular in the Midwest US

Fish Grouped by Fat Content (For the Nutrition Section)

Oily fish (higher omega-3 content):
Salmon, mackerel, sardines, herring, tuna, anchovies, bluefish

Lean white fish (mild flavor, minimal fat):
Cod, tilapia, haddock, sole, flounder, halibut, grouper, pollock

Types of Shellfish

Crustaceans

Shrimp – small, versatile, quick cooking, the most consumed shellfish in the US
Prawns – larger relative of shrimp, often used interchangeably in recipes
Crab – includes several popular varieties:
- Blue crab – common in East Coast crab cakes and boils
- King crab – large, sweet leg meat, often steamed or grilled
- Snow crab – delicate, slightly sweet meat, popular steamed
- Dungeness crab – West Coast favorite, sweet and tender
- Stone crab – claws harvested sustainably, served chilled
Lobster – premium shellfish known for tender tail and rich claw meat
Crawfish (crayfish) – small freshwater crustacean, staple in Southern US boils and étouffée
Krill – tiny shrimp-like crustaceans, mostly used in supplements and as fish feed, occasionally eaten directly in some cuisines

Mollusks: Bivalves

Clams – includes littleneck, cherrystone, and razor clams, eaten steamed, raw, or in chowder
Oysters – eaten raw on the half shell or cooked, valued for briny flavor and zinc content
Mussels – often steamed in wine or broth, quick cooking and affordable
Scallops – firm, sweet meat, popular seared; includes sea scallops and bay scallops

Mollusks: Cephalopods

Squid – mild flavor, chewy texture, often served as calamari
Octopus – requires careful cooking to become tender, popular grilled or braised
Cuttlefish – similar to squid, common in Mediterranean and Asian cuisine

Mollusks: Gastropods

Abalone – a prized sea snail with firm, chewy meat, considered a delicacy
Conch – large sea snail popular in Caribbean cooking, often used in fritters and salads
Sea snails (whelks) – less common in the US but widely eaten in European and Asian cuisine

Shrimp, crab, and lobster seafood infographic

How to Choose the Right Type of Seafood

With so many types of seafood available, choosing the right one often comes down to matching your goals, whether that’s nutrition, budget, cooking skill, or personal taste, to the right category.

If you’re focused on health goals:

For heart health, choose oily fish like salmon, mackerel, or sardines for their high omega-3 content
For weight management, lean options like cod, shrimp, and tilapia offer high protein with minimal fat
For mineral intake, oysters and mussels provide some of the highest zinc and iron levels among all seafood

If you’re working with a budget:

Tilapia, catfish, and canned tuna are among the most affordable options year round
Frozen shrimp often costs less than fresh and works just as well in most recipes
Mussels and clams tend to be cheaper than lobster or crab while still offering rich flavor

If you’re new to cooking seafood:

Start with mild, forgiving options like tilapia, cod, or shrimp, which are hard to overcook badly
Avoid octopus or squid at first, since these require specific techniques to avoid a rubbery texture
Pre-cooked shrimp or canned salmon are good low-risk starting points

If sustainability is a priority:

Look for wild caught labels on species with healthy population levels, such as Alaskan salmon or Pacific cod
Farmed options like tilapia and catfish often have a lower environmental footprint than some wild caught species
Checking for certifications like MSC (Marine Stewardship Council) can help confirm responsible sourcing

If you’re cooking for a specific dish:

Firm fish like tuna, swordfish, or halibut hold up well on the grill
Delicate fish like sole or flounder work best baked or pan seared
Shellfish like shrimp, crab, and mussels are ideal for pasta dishes, boils, and quick weeknight meals

Popular Seafood Dishes by Type

Different types of seafood shine in different dishes, and knowing which pairing works best can make cooking far less intimidating.

Finfish Dishes:

Grilled salmon with lemon and herbs, a simple weeknight staple
Fish and chips, traditionally made with cod or haddock
Tuna poke bowls, featuring raw, marinated tuna over rice
Blackened tilapia, popular in Cajun and Southern US cooking
Sushi and sashimi, showcasing raw tuna, salmon, and yellowtail

Crustacean Dishes:

Shrimp scampi, sautéed in garlic butter and white wine
Crab cakes, a Maryland classic made from lump crab meat
Lobster rolls, chilled or buttered lobster meat served in a bun
Crawfish boil, a Southern tradition combining crawfish, corn, and potatoes
Garlic butter shrimp skewers, common at grilling and barbecue events

Mollusk Dishes:

Oysters on the half shell, served raw with mignonette or lemon
Steamed mussels, cooked in white wine, garlic, and herbs
Clam chowder, a creamy New England classic
Calamari, lightly breaded and fried squid rings
Grilled octopus, often served with olive oil and paprika in Mediterranean cuisine

Mixed Seafood Dishes:

Seafood paella, combining shrimp, mussels, and sometimes squid with saffron rice
Cioppino, an Italian American seafood stew with fish, shellfish, and tomato broth
Seafood boil, mixing shrimp, crab, crawfish, corn, and sausage in one pot
Bouillabaisse, a French seafood stew featuring multiple fish and shellfish varieties

Frequently Asked Questions About Types of Seafood

What is considered seafood?

Seafood refers to any edible aquatic animal harvested from saltwater or freshwater, including fish, crustaceans, mollusks, and cephalopods. Some definitions also include edible sea plants like seaweed due to their marine origin.

What are the main types of seafood?

The main types of seafood are finfish, crustaceans, mollusks, and cephalopods. Finfish includes species like salmon and tuna, crustaceans include shrimp and crab, mollusks include clams and oysters, and cephalopods include squid and octopus.

What is the difference between shellfish and finfish?

Finfish have a backbone, fins, and gills, while shellfish have no backbone and are protected by a shell or exoskeleton. Shellfish further splits into crustaceans, like shrimp and crab, and mollusks, like clams and mussels.

What is the difference between saltwater and freshwater seafood?

Saltwater seafood comes from oceans and tends to have bolder flavors along with higher omega-3 content in species like salmon and tuna. Freshwater seafood, sourced from rivers and lakes, is generally milder in taste and more affordable, with tilapia and catfish being the most common options.

Which seafood has the most protein?

Octopus, tuna, and tilapia rank among the highest protein seafood options, offering 26 to 30 grams of protein per 100 gram serving.

Which seafood has the most omega-3?

Mackerel, salmon, and sardines contain the highest omega-3 levels among common seafood types, making them ideal choices for heart and brain health.

What is the healthiest type of seafood to eat?

Oily finfish like salmon and mackerel rank among the healthiest due to high omega-3 content, while bivalve mollusks like oysters rank highly for zinc, iron, and vitamin B12.

Which seafood is best for beginners to cook?

Mild, forgiving options like tilapia, cod, and shrimp are easiest for beginners, since they are hard to overcook badly compared to more delicate options like octopus or squid.

Is seaweed considered seafood?

Seaweed is technically a sea plant, not an animal, but it is commonly grouped with seafood due to its marine origin and frequent use in seafood focused dishes like sushi.

How do you know if seafood is fresh?

Fresh finfish has firm flesh and a mild ocean smell, live shellfish should move or close when touched, and any strong sour or ammonia like odor signals spoilage across nearly all seafood types.

Conclusion

Seafood covers a far wider world than most people realize, spanning finfish, crustaceans, mollusks, and lesser known options like sea urchin and seaweed. Understanding the different types of seafood makes grocery shopping easier, helps home cooks choose the right preparation method, and supports smarter decisions around nutrition and freshness.

Each category brings something unique to the table, whether it’s the omega 3 richness of salmon, the lean protein of shrimp, or the mineral density of oysters. Knowing how seafood is classified also helps explain differences in allergies, storage needs, and cooking techniques across categories.

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