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Explore Fish

The complete Aquareap fish database — browse by ocean, country, conservation status, habitat, and more. Every species cross-referenced with IUCN Red List data, edibility ratings, and geographic range.

37,094

Species

3,959

Threatened

4,539

Edible

Ocean Regions

120

Countries

Browse Fish By Four ways into the full database

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Ocean & Water Body

Every major ocean, sea, and freshwater basin — from the Indo-Pacific to the Amazon Basin.

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Find fish native to or commonly found in any of 120 countries worldwide.

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IUCN Red List — 3,959 threatened species across 8 categories, from Least Concern to Extinct.

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Marine, freshwater, brackish, and diadromous species — each with distinct ecology, threats, and conservation needs.

IUCN Red List Snapshot 28,702 assessed species Full breakdown →

Threatened (CR/EN/VU) Near Threatened Least Concern Data Deficient Extinct

CR 850 Critically Endangered EN 1,447 Endangered VU 1,662 Vulnerable NT 1,022 Near Threatened LC 18,377 Least Concern DD 5,247 Data Deficient EW 11 Extinct in Wild EX 86 Extinct

Thematic Collections Curated by trait, use, or safety

🍽️ Edible Fish

Rated by flavour, texture & safety

4,539

species

🐠 Aquarium Fish

Beginner to expert care levels

species

🔴 Endangered Fish

CR + EN species facing extinction

2,297

species

⚠️ Venomous Fish

Spines, toxins & first aid guide

713

species

🚨 Invasive Fish

Ecological threats & spread patterns

species

📋 Conservation Status

Full IUCN Red List breakdown

28,702

species

♻️ Sustainable Seafood

MSC certified & Seafood Watch picks

species

🏆 World Records

Biggest, fastest, deepest fish ever caught

☠️ High Mercury

Avoid or limit — mercury risk guide

✅ Low Mercury

Safe for frequent consumption

🧠 Omega-3 Rich

High EPA & DHA content species

🌾 Aquaculture

Farmed fish — industry & sustainability

Ocean & Water Body Regions 8 major water bodies View all →

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Species by Habitat 37,094 with habitat data Habitat guide →

🌊 Marine 18,138 (48.9%)

💧 Freshwater 18,067 (48.7%)

🌿 Brackish 95 (0.3%)

🔄 Diadromous 794 (2.1%)

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Species A–Z Index

Alphabetical listing of all 37,094 species

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Compare Species

Side-by-side stats, habitat, and edibility

The World of Fish: An Introduction to Earth's Most Diverse Vertebrate Group

Fish are the oldest living vertebrates on Earth. They appeared in the fossil record more than 500 million years ago, long before insects colonised the land, long before plants grew taller than mosses, long before anything with a backbone breathed air. In the half a billion years since their first appearance, they have diversified into an astonishing variety of forms — from the eight-millimetre Paedocypris, the world's smallest vertebrate, to the twelve-metre whale shark, the largest fish alive today. They inhabit environments ranging from high-altitude Himalayan streams at over 5,000 metres elevation to deep-sea trenches nearly eleven kilometres below the ocean surface, from polar Arctic seas to hydrothermal vents where water temperatures exceed 350°C. There are currently over 35,000 described species of fish — more than half of all vertebrate species combined — and scientists estimate that thousands more await discovery and formal description.

What Is a Fish? The Surprising Complexity of the Question

The word "fish" sounds simple but describes an extraordinarily diverse group that does not constitute a single natural evolutionary unit. Fish include three distinct evolutionary lineages: jawless fish (Agnatha), comprising lampreys and hagfish, the most ancient vertebrate lineages alive today; cartilaginous fish (Chondrichthyes), including sharks, rays, skates, and chimaeras, whose skeletons are made of cartilage rather than bone; and bony fish (Osteichthyes), the largest and most diverse group, comprising the ray-finned fish (Actinopterygii, about 34,000 species) and the lobe-finned fish (Sarcopterygii, six species of lungfish plus the coelacanths). In evolutionary terms, humans and other tetrapods (amphibians, reptiles, birds, mammals) are actually modified lobe-finned fish — descended from a lobe-finned ancestor that colonised land approximately 375 million years ago.

This evolutionary complexity means that fish are united by their aquatic lifestyle and basic body plan rather than by exclusive common ancestry. A shark and a salmon are no more closely related to each other than a salmon is to a human — yet both are called fish. The term "fish" is therefore best understood as an ecological grade rather than a strict taxonomic category, describing the vast array of aquatic vertebrates that have not made the transition to terrestrial life.

Fish Biology: Form Perfectly Matched to Function

The body plan of a typical bony fish is a masterpiece of evolutionary engineering, finely tuned for life in water. The streamlined, fusiform (torpedo-shaped) body of a fast pelagic fish like a tuna or mackerel minimises drag, while the compressed, disc-like body of a reef fish like an angelfish allows manoeuvrability in tight spaces. The laterally flattened body of a flatfish like plaice or halibut enables perfect cryptic concealment on the seafloor. Form and function are inseparable in fish morphology, and reading the shape of a fish reveals a great deal about where it lives and how it feeds.

The swim bladder — a gas-filled organ evolved from an ancestral lung-like structure — is one of the most elegant solutions in vertebrate evolution. By secreting or absorbing gas to adjust its volume, a fish can precisely control its buoyancy, remaining neutrally buoyant at any depth without swimming effort. The lateral line system — sensory cells arranged in a line along the fish's flanks and on the head — detects water pressure changes and vibrations with such sensitivity that fish can perceive the bow-wave of an approaching predator, navigate by detecting current patterns, and coordinate movement in schools without visual reference.

Fish respiration through gills — highly vascularised tissues that extract dissolved oxygen from water as it flows across them — is extraordinarily efficient, but the efficiency of gill breathing depends on adequate dissolved oxygen. This is why oxygen-depleted water kills fish quickly: unlike mammals that can hold their breath, fish cannot briefly switch to air-breathing when dissolved oxygen drops. The exceptions are remarkable: several groups of tropical freshwater fish have independently evolved accessory breathing organs — the labyrinth organ of gouramis and bettas, the modified gill chambers of snakeheads and walking catfish — that allow them to gulp air and survive in severely oxygen-depleted tropical waters, or even to move overland between pools during droughts.

Fish Senses: Perceiving an Aquatic World

Fish perceive their world through a combination of familiar and entirely alien senses. Vision is important in most fish but is calibrated for aquatic light conditions — many species see ultraviolet wavelengths invisible to humans, while deep-sea fish have evolved eyes with extraordinary light sensitivity to function in near-total darkness. Hearing in fish works fundamentally differently from hearing in air-breathing animals: sound travels much faster and farther in water, and fish hear via both the inner ear and the lateral line system, detecting sounds at frequencies often outside human hearing range. Fish are far from silent — many species produce sounds for communication during spawning, territorial defence, and predator avoidance, and the diversity of fish vocalisations is only now being properly studied.

Electroreception — the ability to detect electric fields in the surrounding water — is one of the most extraordinary senses in the animal kingdom and is found in multiple fish groups. Sharks and rays use passive electroreception (detecting the electric fields produced by other animals' muscle activity) to locate prey hidden in sand or darkness. Electric fish like the electric eel and weakly electric species in tropical rivers use active electrolocation — producing their own electric fields and detecting distortions caused by objects — as a primary sensory modality in turbid water where vision is useless. The electric eel can also use powerful electric organ discharges of up to 860 volts as a weapon to stun prey and deter predators.

Fish Diversity: From Coral Reefs to Arctic Seas

The habitats in which fish are found span virtually every aquatic environment on Earth. Coral reefs, despite covering only 0.1% of the ocean floor, harbour approximately 25% of all marine fish species — a concentration of biodiversity driven by the three-dimensional structure of coral skeletons that creates thousands of distinct micro-habitats. The Amazon River basin alone contains more freshwater fish species than any other river system — approximately 3,000 described species, with estimates that the true total including undescribed species may exceed 5,000. The deep sea below 1,000 metres, covering more than 60% of the Earth's surface, contains fish communities of extraordinary physiological specialisation including bioluminescent anglerfish, jelly-like snailfish inhabiting the deepest ocean trenches, and viperfish with disproportionately large, needle-like teeth.

The deep seas are the final frontier of fish discovery. Expeditions to deep-sea trenches regularly return with species new to science. In 2023, a new snailfish was discovered at 8,336 metres depth in the Izu-Ogasawara Trench — the deepest known fish ever observed — a small, pale, gelatinous creature adapted to pressures that would crush most deep-sea submarines. The vast majority of the ocean's volume has never been systematically surveyed for fish life, and the true diversity of deep-sea fish may far exceed current estimates.

The Importance of Fish to Human Civilisation

No other wild animal group has been as important to human nutrition, culture, and economy as fish. Archaeological evidence of fish consumption dates back hundreds of thousands of years, predating even the earliest evidence of cooking. Coastal communities worldwide have built entire cultures around specific fish species — the salmon cultures of the Pacific Northwest, the cod culture of Atlantic maritime nations, the anchovy-driven economies of the Mediterranean and Humboldt Current regions. Fish provide approximately 17% of global animal protein consumption, rising to over 70% in many island and coastal nations where terrestrial protein alternatives are limited. The global fish trade is worth over $150 billion annually, employing 600 million people directly and indirectly in production, processing, and distribution.

The future of the world's fish depends on how the next generation navigates the intersection of human needs, environmental pressures, and conservation commitments. Aquareap is built on the conviction that knowledge is the foundation of appreciation, and that appreciation is the prerequisite for conservation. Explore 37,000 species, learn what is known and what remains unknown, and discover why the world's most diverse vertebrates deserve our attention, our wonder, and our protection.