I stumbled across (and purchased) a copy of The Complete Crossword Companion recently in a second-hand store.
It's a 1988 edition of two older books combined - Complete Crossword Reference Book (1932) and The Pocket English Dictionary (1976) (both also published in 1983 under the titles The Newnes Crossword Dictionary and Newnes Pocket English Dictionary, respectively).
As I often do with all sorts of reference books, I see if there's anything specifically about fish or fishing in them. In this book I found words divided into letter length (to help with crosswords, obviously) under the title 'Fish, etc.'
... and here they are!
2 letter, 3 letter, 4 letter words
amia, bass, bib, blay, bley, bret, brit, burt, cale, carp, chad, char, chub, clam, cod, coho, crab, cusk, dab, dace, dar, dare, dart, dorn, dory, eel, eft, elva, esox, fash, file, fin, gar, ged, goby, grig, hake, huck, huso, id, ide, jack, kelt, keta, ling, lipp, lomp, luce, mago, mort, newt, opah, orc, orca, orfe, parr, peal, pike, pope, pout, quab, ray, roe, rudd, ruff, sapo, scad, scar, scup, shad, snig, sole, tai, tau, tpe, tuna, tusk, zant
5 letter words
ablen, ablet, allis, angel, apode, banny, beroe, binny, bleak, bleck, bogue, boops, bream, brill, charr, cisco, cobia, cuddy, cudle, doree, dorse, elops, fleck, fusus, gadus, gibel, gummy, guppy, julis, loach, loche, maray, minim, moray, morse, mugil, muray, murry, mysis, myxon, nurse, perch, phoca, piper, pogge, porgy, poulp, powan, prawn, reeve, roach, roker, ruffe, saith, salmo, saury, scrod, scurf, sepia, sewin, shark, skate, smelt, smolt, smout, smowt, snook, solen, sprag, sprat, sprod, squid, sudak, sweep, tench, toado, togue, torsk, troll, trout, tunny, twait, whale, whelk, whiff, witch
6 letter words
alburn, alevin, allice, anabas, barbel, beakie, belone, beluga, blenny, blower, bonito, bounce, bowfin, braise, buckie, burbot, caplin, caranx, cepola, cheven, chevin, clupea, cockle, comber, conger, cultch, cuttle, dagoba, dentex, diodon, doctor, dugong, dun-cow, ellops, finnan, gadoid, ganoid, gardon, ginkin, goramy, grilse, groper, gunnel, gurnet, hilsah, hussar, isopod, jerkin, kipper, launce, loligo, margot, meagre, medusa, megrim, milter, minnow, morgay, mud-eel, mullet, mussel, narwal, otaria, oyster, partan, plaice, pollan, porgie, poulpe, puffer, puller, quahog, redcap, red-cod, red-eye, remora, robalo, rochet, romero, roughy, ruffin, runner, sabalo, sadina, saithe, salmon, samlet, sander, sardel, sauger, saurel, saynay, scarus, scurff, sea-ape, sea-bat, sea-cow, sea-dog, sea-egg, sea-fox, sea-hog, sea-owl, see-pad, see-pig, sephen, shanny, shiner, shrimp, snacol, soosoo, sucker, tailor, tarpon, tarpum, tautog, tawtog, tiburo, tomcord, trygon, turbit, turbot, twaite, ulican, urchin, vendis, wapper, weever, whaler, winkle, wirrah, wrasse, zander, zeidae, zingel
7 letter words
abalone, acaleph, actinia, ale-wife, anchovy, asterid, batfish, bergylt, bloater, blue-cap, blue-eye, bocking, bonetta, box-fish, brassie, bubbler, bummalo, calamar, capelin, cat-fish, catodon, cetacea, cichlid, cidaris, cod-fish, codling, cow-fish, crabite, croaker, crucian, crusien, cyprine, dog-fish, dolphin, drummer, dun-fish, echinus, eel-fare, eel-pout, escolar, fiddler, fin-back, fin-fish, garfish, garpike, garvock, girrock, gladius, goldney, gourami, gournet, grampus, grouper, grundel, grunter, gudgeon, gunard, gwiniad, gwyniad, haddock, halibut, herling, herring, homelyn, houting, jewflsh, keeling, lampern, lamprey, latchet, lobster, long-tom, mahseer, manatee, manchet, merling, monodon, moon-egg, morwong, mud-fish, muraena, murexes, murices, narwhal, nautili, oar-fish, octopus, old-wife, pandore, pegasus, pen-fish, pig-fish, pointer, pollack, pollard, pollock, polypus, pomfret, quinnet, rat-tail, red-fish, reef-eel, ripsack, rock-cod, ronchil, ronquil, rorqual, sand-eel, sardine, sawfish, schelly, scomber, sea-bear, sea-calf, sea-fish, sea-lion, sea-pike, sea-wolf, shadine, silurus, skegger, smerlin, snapper, sock-eye, spawner, sphyrna, squalus, sterlet, stripey, sun-fish, thwaite, tiddler, top-knot, torgoch, torpedo, tub-fish, ulichon, umbrine, vendace, whiting, worm-eel, xippias
8 letter words
acalepha, albacore, albicore, ammodyte, anableps, anguilla, asterias, band-fish, barnacle, bill fish, blue fish, boarfish, bullhead, cachalot, cackerel, calamory, cetacean, coalfish, corystes, crawfish, crayfish, dapedium, dapedius, dragonet, drum-fish, eagle-ray, errantes, eulachon, exocetus, file-fish, fin-scale, fire-fish, flagtail, flatfish, flathead, flounder, forktail, fox-shark, frog-fish, gillaroo, gilt-head, glass-eel, goatfish, goldfish, graining, grayling, green eel, grub-fish, gymnotus, hair-tail, halicore, hand-fish, horn-beak, horn-fish, jentling, John Dory, jugulars, kelp-fish, king crab, king-fish, lady-fish, lancelet, land crab, lump-fish, lung-fish, mackerel, melanure, menhaden, moon-fish, moray eel, mormyrus, nannygai, numbfish, ophidion, pickerel, pigmy-eel, pilchard, pipe-fish, polyneme, Poor John, porpoise, raft-fish, red perch, rock-cale, rock-fish, rockling, sail-fish, salt-fish, sand-fish, sardelle, saw-shark, sea-devil, sea-horse, sea-perch, sea robin, shore-eel, siskiwit, snake-eel, sparling, spelding, speldrin, speldron, spirling, springer, spurling, starfish, sting-ray, sturgeon, sun-bream, surf-fish, tarwhine, teraglin, testacea, thornbut, thrasher, thresher, toad-fish, trevalla, troutlet, tusk-fish, water-fox, weed-fish, wolf-fish
9 letter words
acalephae, acipenser, angel-fish, Argentine, ascidians, asteroida, barracuda, blackfish, black sole, blue nurse, blue shark, blue sprat, bony bream, bulltrout, bummaloti, calamarys, chaetodon, cling-fish, cole-perch, conger eel, coral fish, coryphene, cover-clip, crampfish, crustacea, devil fish, dolphinet, echinidan, engraulis, finny-scad, fire-flair, fish-royal, fortesque, frost-fish, globe-fish, golomynka, grey nurse, hard-belly, hardyhead, hippodame, houndflsh, hybodonts, jaculator, jellyfish, John Dorée, jollytail, kingstone, mango fish, menominee, murray cod, pilot fish, porbeagle, pyllopodo, razor fish, red mullet, river crab, roundhead, sand-lance, saury-pike, schnapper, sea-mullet, sea-needle, sea-nettle, sea-urchin, sheat-fish, silver-eel, spear-fish, stargazer, stingaree, sting-fish, stink-fish, stockfish, stomapoda, suctorian, surmullet, sweetlips, swordfish, thorn-back, threadfin, tittlebat, troutling, trumpeter, tunny fish, whitebait, whitefish, wobbegong
10 letter words
amblyopsis, amphytrite, angel-shark, angler fish, banstickle, barracoota, barracouta, basket fish, black bream, black whale, blind shark, blue groper, blue puller, bottle-nose, brown trout, butterfish, cestracion, clouded eel, clypeaster, cock-paddle, coelacanth, cowanyoung, ctenoidans, cuttlefish, demoiselle, dragon-fish, echinoderm, fiddle-fish, fingerling, fistularia, flute-mouth, flying fish, ganoidians, garter fish, ghost-shark, giant toado, goblin-fish, great skate, grey mullet, groundling, hammerhead, hermit crab, holothuria, knight-fish, loggerhead, lumpsucker, mirror dory, morris pike, Moses perch, parrot-fish, pearl perch, periwinkle, pigmy perch, pycnodonts, rapier fish, red gurnard, red morwong, red rockcod, ribbon-fish, rudder-fish, Samsonfish, sand-hopper, sand-mullet, sandy sprat, sea-garfish, sea-leopard, sea poacher, sea-unicorn, silver dory, silverfish, silverside, sperm whale, square-tail, sturionian, sucker-fish, tailor-fish, tassel-fish, tiger shark, tongue-sole, triple-tail, turret-fish, velvet-fish, weaver-fish, whale-shark, white shark, yellow-tail, zebra shark
11 letter words
balance-fish, banded toado, bellows-fish, black-angler, blue-pointer, bridled goby, brown-groper, brown-puller, carpet-shark, carp-gudgeon, chanda perch, common skate, common toado, crested goby, cycloidians, electric eel, electric ray, finner-whale, five-fingers, golden perch, green turtle, gurnet perch, herring-cale, hippocampus, jackass-fish, javelin-fish, Jumping-Joey, kingsnapper, leatherskin, leopard-fish, lepidosiren, little tunny, man-o'-war fish, Moorish idol, orange perch, peacock-fish, peacock-sole, pennant-fish, prickleback, pterichthys, rainbow-fish, red bullseye, red fire-fish, rock-whiting, salmon-trout, sand-whiting, school-shark, scleroderms, sea-elephant, sea-scorpion, silver-belly, silver perch, silver toado, smooth toado, soldier-crab, soldier-fish, starry toado, sticklebeck, stonelifter, surgeon-fish, swallow-fish, tallegalane, trumpet-fish, whistle-fish, wolf-herring
12 letter words
basking shark, black drummer, black rock-cod, blue trevally, coachwhip ray, cucumber-fish, dipterygians, dusky morwong, fan-tailed ray, fatherlasher, fighting-fish, forehead-fish, gargoyle-fish, giant herring, gray tusk-fish, oyster-blenny, painted saury, piked dog-fish, plectognathi, Plesiosaurus, rainbow-trout, rat-tailed ray, river garfish, rock flathead, scarlet bream, sentinel crab, silver mullet, smooth angler, Stout Long-Tom
13 letter words
allports perch, banded-pigfish, barred-garfish, Barred Long-Tom, black king-fish, black-trevally, branchiostoma, climbing perch, dactylopterus, dusky flathead, entomostracan, findon-haddock, finnan-haddock, flying gurnard, giant boar-fish, horse-mackerel, leafy seahorse, leatherjacket, long-finned eel, magpie-morwong, marbled angler, mountain-trout, ox-eyed herring, porcupine-fish, Red-Indian fish, salmon catfish, salt-water fish, sandpaper-fish, scarlet angler, Sergeant Baker, silver batfish, silver drummer, snub-nosed dart, southern tunny, spiny flathead, spiny seahorse, striped angler, thresher-shark, tiger-flathead
14 letter words
banded sea-perch, black stingaree, branchiostegan, brown-sweetlips, butterfly-bream, enaliosaurians, estuary cat-fish, Greenland-shark, Greenland-whale, king barracouta, king parrot-fish, little nurnbfish, Macquarie perch, many-banded sole, marine annelida, one-finned shark, painted gurnard, purple sea-perch, red gurnet-perch, river blackfish, short-finned eel, shovel-nosed ray, Slender Long-Tom, smooth flathead, spotted whiting, striped catfish, striped gudgeon, striped sea-pike, white horse-fish
15 letter words
acanthopterygii, Australian perch, Australian smelt, beaked coral-fish, bottle-nose shark, common stingaree, crusted flounder, crusted weed-fish, edriophthalmata, frigate mackerel, hairback herring, little cling-fish, little conger eel, long-finned perch, marbled flathead, painted dragonet, short sucker-fish, small-headed sole, smooth stingaree, spangled grunter, Spanish mackerel, spermaceti whale, spotted cat-shark, spotted eagle-ray, spotted pipe-fish, white-spotted ray