Fish

Isinglass

Isinglass (Ichthyocolla): collagen from dried fish swim bladders, best from sturgeon, used to fine beer and wine and historically as the strongest glue in England; not vegan, low allergen risk.

Isthmus Caribbean (FEOW ecoregion 207) is a freshwater ecoregion of Caribbean-slope rivers in Costa Rica and Panama, from the Rio Sixaola to the Rio Calovebora, with 42% endemic freshwater fish fauna.

Isurus paucus

Isurus paucus, the longfin mako shark, is a rare oceanic Lamnidae shark of tropical and warm-temperate seas, distinguished from the shortfin mako by long pectoral fins, litters of 2-8 pups, and IUCN Endangered status.

Jenny Haniver

Jenny Haniver: a fake sea monster made from a dried, cut, and folded ray, skate, or guitarfish; also called devil fish or Diablito. First depicted in Gesner's Historia Animalium (1558); name possibly from jeune d'Anvers, first published 1928.

Jersey Shore shark attacks of 1916

Jersey Shore shark attacks of 1916: five shark attacks along the New Jersey coast, July 1-12, 1916, killed four people and injured one, sparking America's first shark panic, a federal response under Wilson, and the rogue-shark legend behind Jaws.

John Dory

John Dory (Zeus faber, St Peter's fish, kuparu) is a compressed, spot-marked demersal fish of family Zeidae found in Atlantic, Indian and Pacific temperate waters, fished commercially and listed IUCN Data Deficient.

Kajikia audax

Kajikia audax, the striped marlin (formerly Tetrapturus audax), an Indo-Pacific billfish of family Istiophoridae; up to 420 cm and 440 kg, epipelagic at 20-25°C, sashimi-valued, IUCN Least Concern but several regional stocks overfished.

Kamaboko (蒲鉾)

Kamaboko (蒲鉾) is the Japanese surimi fish cake, steamed or broiled on a board, first recorded in the Heian period; Japan produced about 361,691 tons in 2025 after decades of decline.

King mackerel

King mackerel (Scomberomorus cavalla), also called cavalla or sierra, is a large western Atlantic coastal pelagic fish reaching 5.5 feet and 100 pounds, managed as Gulf and South Atlantic U.S. stocks and high in mercury (0.73 ppm).

Koi (鯉)

Koi (鯉), known in Japan as nishikigoi, are colorful ornamental carp first bred by rice farmers in Niigata Prefecture in the early 19th century, with over 150 varieties today.

Koi herpesvirus disease

Koi herpesvirus disease (KHVD), caused by Cyprinid herpesvirus 3 (CyHV-3, KHV), is a notifiable, highly contagious carp disease with 70-100% mortality, temperature-dependent latency, and global spread via the koi trade.

Koryakia

Koryakia (FEOW ecoregion 612) is a temperate coastal rivers freshwater ecoregion on the Koryakiya Plateau and Northern Kamchatka, Russia, draining to the Sea of Okhotsk and Bering Sea, with endemic whitefish Coregonus subautumnalis in the Penzhina River.

Labridae

Labridae, the wrasses (including parrotfishes and cales), is a species-rich family of shallow-water coastal marine fishes, about 600-676 species, second largest marine fish family, with cleaning behavior, protogynous sex change, and a Cretaceous origin near 79 Ma.

Labrus bergylta

Labrus bergylta, the ballan wrasse (Norwegian berggylt), a large protogynous hermaphrodite labrid fish of the eastern Atlantic from Norway to Morocco, farmed and caught as a cleaner fish against salmon lice; IUCN Least Concern.

Lake trout

Lake trout (Salvelinus namaycush), also called laker or mackinaw, is North America's largest freshwater char, native from Alaska to Nova Scotia and the Great Lakes, a deepwater apex predator restored in Lake Superior after sea lamprey collapse but invasive west of the Rockies.

Lamniformes

Lamniformes (mackerel sharks), order Garman 1885 of Elasmobranchii; 15 living species in 7 families including great white, threshers, basking, megamouth, goblin sharks; over 360 fossil species from ~135 Ma, including Otodus megalodon.

Lampetra fluviatilis

Lampetra fluviatilis, the European river lamprey or lampern, is an anadromous parasitic lamprey of Atlantic Europe, IUCN Near Threatened (A2ce) since 2023, with a 2.5–4.5-year larval stage, 1–2 years at sea, and declining fisheries.

Lamprey

A lamprey, sometimes called a lamprey eel, is a jawless, eel-shaped fish with a round sucker mouth and rasping tongue instead of jaws, with about 50 species worldwide.

Lancelet

Lancelet (amphioxus, cephalochordate): small burrowing marine filter-feeder, basal chordate subphylum Cephalochordata, ~35 species in Branchiostoma, Epigonichthys, Asymmetron; notochord, no backbone, no genome duplication; key evo-devo model.

Lanea

Lanea is an extinct Early Devonian conodont genus (Spathognathodontidae) established by Murphy and Valenzuela-Rios in 1999, type species Ozarkodina eleanorae; its middle Lochkovian lineage of Pa elements underpins global Lochkovian biozonation.

Lanternfish

Lanternfish (Myctophidae), about 250 species of small bioluminescent mesopelagic fishes with species-specific photophores, dominate the ocean twilight zone, migrate vertically nightly, and anchor global mesopelagic biomass estimates.

Largemouth bass

Largemouth bass (Micropterus nigricans, formerly M. salmoides) is a large North American freshwater sunfish and premier sport fish; up to 38.2 inches and 22 pounds, nest-building spring spawner, widely stocked and invasive outside its native range.

Larimichthys crocea

Larimichthys crocea (大黄鱼), the large yellow croaker, is a northwest Pacific sciaenid fish whose wild stocks collapsed after 1970s overfishing; it is now China's top marine aquaculture fish, IUCN Critically Endangered in the wild.

Larimichthys polyactis

Larimichthys polyactis, the small yellow croaker (Japanese キグチ), is a Sciaenidae fish endemic to the Bohai, Yellow, and East China Seas; a highly commercial bottom-trawl species now assessed as overexploited in the Yellow Sea.

Lateolabrax japonicus

Lateolabrax japonicus (suzuki, Japanese seabass), a western Pacific coastal perch of Lateolabracidae described by Cuvier in 1828; catadromous, protandrous (males change sex at age 2), up to 102 cm and 8.7 kg, IUCN Least Concern, farmed commercially in China and Korea.

Latimeria

Latimeria, the modern coelacanth, is a genus of lobe-finned fish containing the only two living coelacanth species, one caught off South Africa in 1938 after the group was thought extinct.

Latimeria chalumnae

Latimeria chalumnae, the West Indian Ocean or African coelacanth, a lobe-finned fish rediscovered alive off South Africa in 1938; Critically Endangered, CITES Appendix I, ovoviviparous, genome sequenced 2013.

Leafy seadragon

Leafy seadragon (Phycodurus eques, Glauert's seadragon): a camouflaged syngnathid fish of southern Australia's kelp reefs, 3-50 m deep, males brooding eggs on the tail, protected, IUCN Least Concern/Near Threatened.

Leedsichthys

Leedsichthys (Leedsichthys problematicus) is an extinct giant pachycormiform ray-finned fish from the Middle to Late Jurassic, about 165–152 million years ago, the largest bony fish ever at up to 16.5 m and roughly 44.9 tonnes, a plankton filter feeder known only from fragmentary fossils.