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All Fish Species A–Z

Browse every species in the Aquareap database - from the humble anchovy to the mighty yellowfin tuna. Filter by habitat, type, or search by common or scientific name.

37,094

Total Species

4,539

Edible Species

10,674

Aquarium Fish

1,424

Game Fish

A 3.1k B 3.3k C 3.1k D 1.2k E 1.1k F 752 G 1.8k H 1.8k I 441 J 301 K 490 L 2.1k M 2k N 993 O 1.2k P 3.6k Q 34 R 1.6k S 4.7k T 1.8k U 105 V 261 W 678 X 76 Y 452 Z 138

Showing Letter: K 490 species

Knodus Septentrionalis

Knodus septentrionalis

Knoepffler's Elephantfish

Boulengeromyrus knoepffleri

Mesogobius batrachocephalus

LC Freshwater 🐠

Knysna sandgoby

Psammogobius knysnaensis

Kobayashi's bristlemouth

Cyclothone kobayashii

LC Marine

Kobayashi's triangular batfish

Malthopsis kobayashii

LC Marine

Kobe flounder

Crossorhombus kobensis

LC Marine

Kochichthys Flavofasciatus

Kochichthys flavofasciatus

Koefoed's smooth-head

Bathytroctes macrolepis

LC Marine

Koester

Acanthistius sebastoides

Kokoda glass perchlet

Tetracentrum caudovittatus

Kokraimoro tube-snouted ghost knifefish

Sternarchorhynchus kokraimoro

VU Freshwater

Kokuni

Chrysichthys cranchii

LC Freshwater ⚠️

Kola rainbowfish

Melanotaenia kolaensis

LC Freshwater 🐠

Kolombatovic's goby

Chromogobius zebratus

Kolpotocheirodon Figueiredoi

Kolpotocheirodon figueiredoi

CR Freshwater

Kolpotocheirodon Theloura

Kolpotocheirodon theloura

Ostorhinchus komodoensis

Marine 🐠

Komodo damselfish

Pomacentrus komodoensis

Komodo viviparous brotula

Ungusurculus komodoensis

Marine

Komodo whiptail

Pentapodus komodoensis

Marine

Kongoro lampeye

Lacustricola kongoranensis

LC Freshwater 🐠

Koningsberger's herring

Herklotsichthys koningsbergeri

LC Diadromous

Konti barb

Osteochilichthys thomassi

Glossogobius koragensis

Korean darter dragonet

Callionymus leucopoecilus

Dictyosoma tongyeongensis

Hypoptychus dybowskii

Scomberomorus koreanus

Ophichthus sangjuensis

Marine

Korean stumpy bullhead

Coreobagrus brevicorpus

Koreocobitis Naktongensis

Koreocobitis naktongensis

Freshwater

Korhi barb

Hypselobarbus micropogon

Carasobarbus kosswigi

VU Freshwater 🐠

Kosswig's loach

Turcinoemacheilus kosswigi

LC Freshwater 🐠

Kotaka's argentine

Glossanodon kotakamaru

Mataeocephalus kotlyari

Monodactylus kottelati

Kottelatlimia Hipporhynchos

Kottelatlimia hipporhynchos

Kottelatlimia Pristes

Kottelatlimia pristes

VU Freshwater 🐠

Kotthaus' deepwater dragonet

Callionymus kotthausi

Kraemeria Galatheaensis

Kraemeria galatheaensis

Krefft's Blind Numbfish

Symbolophorus kreffti

LC Marine

Fish Species: A Guide to the World's 35,000+ Fish and How to Explore Them

With more than 35,000 described species, fish represent over half of all living vertebrates - a number so large that it defies easy comprehension. New species are formally described by scientists at a rate of several hundred per year, meaning the total continues to grow with each publication cycle. Aquareap's species index brings this entire diversity into one browsable, searchable catalogue, making it possible to move from the most familiar household names - Atlantic salmon, clownfish, great white shark - to the entirely obscure: cave-dwelling cavefish without eyes, electric eels generating 860 volts, and tiny gobies that never exceed a centimetre in length. Understanding how fish are classified, what makes each species unique, and how to use species data effectively transforms browsing into genuine discovery.

How Fish Species Are Named and Classified

Every fish species carries two scientific names: a genus name (shared with its closest relatives) and a species epithet (unique to that species), together forming a binomial that is universally recognised regardless of language. Atlantic cod is Gadus morhua in English, morue in French, Kabeljau in German - but Gadus morhua everywhere in science. This Linnaean binomial nomenclature, established in 1758 in Carl Linnaeus's Systema Naturae, has governed biological naming for over 260 years and remains the lingua franca of biodiversity science. Beyond binomials, species are grouped into progressively broader taxonomic ranks - genus, family, order, class - that reflect evolutionary relationships. Knowing that a fish belongs to the family Cichlidae tells an experienced aquarist more about its likely behaviour, water requirements, and care needs than any common name could.

Common names, by contrast, are wonderfully chaotic. The same species may have dozens of different common names across regions, languages, and cultural traditions - and the same common name may apply to entirely different species in different places. "Bream" refers to Abramis brama in British freshwater, to various Acanthopagrus species in Australian waters, and to a range of unrelated species across the world. Scientific names are therefore the only reliable way to ensure you are communicating about the same organism, which is why Aquareap displays both names prominently for every species.

The Three Major Groups: An Overview

Jawless fish (Agnatha) are the most ancient fish lineage, descended from the first vertebrates to appear on Earth more than 500 million years ago. Today only two orders survive: lampreys (Petromyzontiformes) and hagfish (Myxiniformes). Lampreys are best known for the parasitic lifestyle of many species - attaching to host fish with a circular, toothed sucker and rasping through scales and skin to feed on blood and body fluids. Despite their unsavoury feeding method, lampreys are ecologically important and, for many species, represent conservation success stories after dam removal allowed population recovery in North American and European rivers. Hagfish are deep-sea scavengers that have the remarkable ability to produce vast quantities of sticky slime when threatened - a defensive system so effective that a single hagfish can fill a bucket with slime within seconds.

Cartilaginous fish (Chondrichthyes) - the sharks, rays, skates, and chimaeras - number approximately 1,100 species and have been swimming Earth's oceans for over 400 million years, making them one of the most evolutionarily durable vertebrate lineages. Their skeletons of cartilage rather than bone make them lighter and more flexible than bony fish, their multiple rows of continuously replaced teeth mean they never run short of cutting tools, and their electroreceptive system (the ampullae of Lorenzini) allows them to detect the bioelectric fields of prey hidden in sand or darkness. Sharks occupy apex predator roles in virtually every ocean ecosystem, and their removal through overfishing causes cascading effects throughout marine food webs. Rays have secondarily adopted flattened body plans ideal for bottom-dwelling, with many species burying themselves in sand to ambush prey or avoid predation.

Bony fish (Osteichthyes) encompass the vast majority of fish species and include essentially everything that most people would picture when thinking of a fish. The ray-finned fish (Actinopterygii, approximately 34,000 species) range from ancient, primitive species like sturgeon and bowfin through the explosively diverse teleosts - the dominant group in virtually every aquatic ecosystem today. Teleosts underwent a spectacular adaptive radiation beginning approximately 150 million years ago, filling every ecological role in freshwater and marine environments with solutions so diverse that no other vertebrate group comes close to matching their ecological breadth.

Reading a Species Profile: What the Data Tells You

Each Aquareap species profile consolidates data from multiple sources into a structured overview. Maximum length is typically the longest reliably recorded specimen for that species, which may significantly exceed the average adult size in most populations. Trophic level - expressed on a scale from 2 (pure herbivore/detritivore) to 5 (apex predator eating only other predators) - describes where in the food chain a species feeds, with most fish falling between 2.5 (omnivore with plant emphasis) and 4.5 (predator of predators). Species with trophic levels above 4 tend to bioaccumulate environmental contaminants like mercury more heavily than lower-trophic-level species.

IUCN Red List status gives the most authoritative available assessment of conservation concern. LC (Least Concern) indicates no significant threat to the population; NT (Near Threatened) indicates the species approaches the threshold for a threatened category; VU, EN, and CR (Vulnerable, Endangered, Critically Endangered) indicate progressively higher extinction risk with specific population decline or range restriction criteria met. DD (Data Deficient) does not mean a species is safe - it means there is insufficient data to assess it, which in fish often means a poorly studied species that warrants research investment as a conservation priority.

Habitat (freshwater, marine, brackish, diadromous) provides immediate context for where a species lives and what conditions it requires. Depth range indicates the vertical extent of a species' distribution - crucial for commercial fisheries targeting specific depth zones and for understanding which species are accessible to different fishing methods. Edibility and related culinary data draws on human uses information to characterise each species' value as food and any specific preparation requirements.

Species Discovery: The Research Frontier

Despite centuries of fish taxonomy, species discovery continues at a remarkable pace. In any given year, several hundred new fish species are formally described and published in peer-reviewed journals. The hotspots for new species discovery are predictable: the deep sea, where technology continues to open new habitats to systematic sampling; the Amazon and its tributaries, where the sheer size and inaccessibility of the system means vast areas have never been comprehensively surveyed; the freshwaters of Southeast Asia and sub-Saharan Africa, where political and logistical challenges have historically limited research; and coral reef environments, where small-bodied cryptic species - tiny gobies, blennies, and wrasses - occupy micro-habitats that require targeted, intensive sampling to reveal.

Molecular tools have transformed species discovery. DNA barcoding - sequencing a standardised gene region from a tissue sample and comparing it to reference databases - can identify whether a specimen represents a known or potentially novel species in hours rather than the weeks of morphological examination that traditional taxonomy requires. Entire ecological assemblages can now be characterised through environmental DNA (eDNA) analysis - collecting water samples and sequencing the DNA shed by organisms living in that water, without physically capturing or seeing any of the fish present. These approaches are producing species lists for remote rivers and reef systems that would have taken decades of traditional survey work.

Using the Species Index

The Aquareap species index can be explored alphabetically, filtered by habitat, IUCN status, edibility, and other attributes, or searched directly by common or scientific name. Each species page links to related species within the same genus and family, making it easy to explore radiations of related species - the 300 species of the goby family Gobiidae, the 130-odd species of tuna and mackerel family Scombridae, the 2,000+ cichlid species. Use the habitat filters to compare freshwater and marine diversity or focus on a specific ecological guild. The conservation status filter immediately surfaces the species under greatest pressure - a starting point for understanding which fish are most in need of attention and protection.