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.