What Fish Are Not Considered Shellfish?

According to the Food and Allergy Anaphylaxis Connection Team (FAACT), a shellfish allergy is different from a fish allergy, meaning that those with one type of allergy do not necessarily have to avoid the other. Knowing what fish are not considered shellfish is critical for anyone managing a food allergy, cooking a diverse range of seafood, or simply understanding the key distinctions in aquatic life. All finfish, which are aquatic vertebrates with backbones and fins, fall into this category and are distinct from invertebrates like crustaceans and mollusks.

Quick Summary

All finfish, including common varieties like salmon, tuna, cod, and tilapia, are not considered shellfish because they possess an internal backbone and fins, unlike invertebrates such as crustaceans and mollusks. Learn the biological differences, explore a variety of safe finfish, and understand the necessary precautions for avoiding cross-contamination when cooking seafood for those with allergies.

Key Points

• Finfish are Vertebrates: Unlike shellfish, finfish have an internal backbone and fins, making them biologically distinct.

• Shellfish are Invertebrates: They are categorized into crustaceans (like crab, lobster, and shrimp) and mollusks (including clams, oysters, and squid).

• Allergy to One Does Not Imply Allergy to Both: A shellfish allergy is separate from a fish allergy; a person can be allergic to one and not the other.

• Many Finfish Options Exist: A wide variety of fish, including salmon, tuna, cod, halibut, and tilapia, are not shellfish and are safe for most people.

• Cross-Contamination is a Risk: For those with allergies, precautions must be taken during food preparation to avoid contact between finfish and shellfish.

• Check Labels Carefully: Processed foods can contain hidden shellfish ingredients, so meticulous label-reading is essential.

Understanding the Distinction Between Finfish and Shellfish

While many people use the term 'seafood' to broadly refer to all edible aquatic life, the biological and culinary differences between finfish and shellfish are significant. The primary distinguishing factor lies in their skeletal structure. Finfish are vertebrates, meaning they have an internal skeleton with a backbone and fins. Shellfish, on the other hand, are invertebrates, meaning they have no internal bones. Instead, they are defined by an external shell or shell-like exterior. This fundamental anatomical difference is the reason why a person can be allergic to shellfish but still safely consume finfish.

The Two Main Groups of Shellfish

To fully understand what fish are not considered shellfish, it's helpful to know what shellfish are. Shellfish are divided into two main categories: crustaceans and mollusks.

Crustaceans

This group is characterized by a hard, jointed external skeleton. Common examples of crustaceans include:

• Crab: Such as blue crab and Dungeness crab.
• Lobster: Including American and spiny lobsters.
• Shrimp and Prawns: Widespread and popular choices.
• Crayfish: A freshwater crustacean, also known as crawfish.

Mollusks

This diverse group often has a hard, hinged shell but can also include soft-bodied cephalopods. Examples of mollusks include:

• Clams: Such as littleneck and surf clams.
• Oysters: Known for their distinctive shells.
• Mussels: Commonly found in coastal areas.
• Scallops: Recognized for their fan-shaped shells.
• Squid and Octopus: Classified as cephalopod mollusks.

A Comprehensive List of Fish That Are Not Shellfish

Virtually all commonly eaten fish with scales and fins fall into the non-shellfish category. This means a vast array of delicious and healthy options are available. The following lists provide an overview of some of the most popular choices, categorized by type.

Fatty/Oily Fish

These are known for their high omega-3 fatty acid content and rich flavor.

• Salmon: A versatile and popular choice, farmed and wild.
• Tuna: Including albacore, yellowfin, and skipjack.
• Mackerel: Atlantic and Spanish varieties are common.
• Herring: A small, oily fish, often smoked or pickled.
• Sardines: Packed with nutrients, frequently canned.

White/Lean Fish

These have delicate, mild-flavored, and flaky white flesh, perfect for various cooking methods.

• Cod: A widely consumed white fish.
• Haddock: Related to cod, with a slightly sweeter taste.
• Halibut: A large flatfish with firm, mild meat.
• Flounder: A delicate flatfish with a mild flavor.
• Tilapia: A mild-flavored freshwater fish, popular for farming.
• Snapper: Such as red snapper, known for its sweet, firm flesh.
• Mahi-mahi: Also known as dolphinfish (not related to marine mammals).
• Sole: A lean flatfish, including Dover and lemon sole.

Freshwater Fish

Often raised in lakes, rivers, or ponds, these are also finfish.

• Trout: Including rainbow trout.
• Catfish: A staple in many cuisines, particularly Southern US.
• Perch: Found in both freshwater and saltwater.

Comparison Table: Finfish vs. Shellfish

To clarify the differences, this table highlights the key characteristics of finfish and shellfish.

Feature	Finfish	Shellfish
Skeletal Structure	Internal backbone (vertebrate)	External shell or soft body (invertebrate)
Body Covering	Scales or smooth skin	Hard shell or exoskeleton
Example (Crustacean)	N/A	Crab, Shrimp, Lobster
Example (Mollusk)	N/A	Clam, Oyster, Scallop
Omega-3s	Often excellent source (especially oily fish)	Present, but often less concentrated
Common Allergies	Separate from shellfish allergy	One of the most common food allergies

Important Considerations for Those with Shellfish Allergies

For those with a shellfish allergy, simply knowing which fish are not considered shellfish is not enough. It's crucial to take precautions to prevent cross-contamination, a major concern for severe allergic reactions. When dining out or preparing food, follow these guidelines:

In the Kitchen

• Separate Utensils and Cookware: Use separate cutting boards, knives, and pans for finfish and shellfish. For example, a cutting board used for shrimp should not be used for salmon.
• Dedicated Cooking Areas: If possible, cook finfish in a separate area from shellfish, or thoroughly clean all surfaces in between. Never use the same oil to fry shrimp and then fish.
• Read Labels Meticulously: Many processed foods, sauces, and stocks contain hidden shellfish ingredients, such as shrimp paste or clam broth. Always read the ingredients list carefully.
• Consider Imitation Products: Some imitation seafood products, like imitation crab meat (surimi), can contain trace amounts of shellfish or be produced on the same equipment. Check the label or avoid entirely if the allergy is severe.

When Dining Out

• Inform the Staff: Clearly communicate your shellfish allergy to your server, explaining the severity and requesting that your meal be prepared in a separate, clean area. Ask them to inform the kitchen staff.
• Question Preparation Methods: Ask about how different dishes are prepared. Is the fish grilled on the same surface as shrimp skewers? Is the fryer oil used for fried calamari also used for fish and chips?
• Opt for Non-Seafood Restaurants: To be completely safe, consider dining at restaurants that do not serve shellfish, minimizing the risk of cross-contamination.

Conclusion: A Clear Choice for Safe Seafood Enjoyment

Understanding what fish are not considered shellfish is fundamental for safe eating, particularly for individuals with shellfish allergies. The key takeaway is the biological difference: finfish are vertebrates with bones, while shellfish are invertebrates with exoskeletons. This distinction allows those with a shellfish allergy to enjoy a wide variety of protein-rich, omega-3-packed finfish, from flaky cod and halibut to oily salmon and tuna. By combining this knowledge with careful kitchen practices and clear communication in restaurants, individuals can navigate their dietary needs confidently and safely enjoy the benefits of a diverse seafood diet.

Visit the U.S. Environmental Protection Agency's guide for choosing fish and shellfish wisely for more on health benefits and risks.

Frequently Asked Questions

Is salmon considered a shellfish?

No, salmon is not a shellfish. It is a finfish, which is a vertebrate with an internal skeleton and fins. Shellfish are invertebrates, lacking a backbone.

Can someone with a shellfish allergy eat fish?

Yes, generally. A shellfish allergy is distinct from a fish allergy, so an individual with a shellfish allergy can typically eat finfish like salmon or tuna, provided there is no cross-contamination.

What is the primary difference between finfish and shellfish?

The primary difference is their skeletal structure. Finfish have an internal backbone, while shellfish are invertebrates and have an external shell or no bones at all.

Are octopus and squid considered shellfish?

Yes, octopus and squid are considered shellfish. They belong to the mollusk group, a category of shellfish.

What types of fish are safe for people with a crustacean allergy?

People with a crustacean allergy can safely eat any finfish, including common varieties like cod, tilapia, halibut, and tuna, as long as care is taken to avoid cross-contamination.

Is tilapia a shellfish?

No, tilapia is a freshwater finfish and is not considered a shellfish. It has scales and a backbone, distinguishing it from crustaceans and mollusks.

How can I avoid cross-contamination when cooking seafood?

To prevent cross-contamination, use separate utensils, cutting boards, and cookware for finfish and shellfish. Never use the same oil for frying both, and thoroughly clean all surfaces between preparations.