|MadSci Network: Zoology|
The Jewish interpretation of the word scales is the critical element. According to Orthodox Jewish interpretation, a scale must be an external element that can be removed without tearing the skin of the fish. Thus, traditional fish with removable scales are all accepted as meeting the Biblical injunction. All such fish also have fins, so the scales are considered the determining factor. There is a long list of fish with these properties, basically from a scientific point of view it is fish with cycloid and ctenoid scales. Some fish have no scales while others have placoid and ganoid scales which are not what one thinks of as scales, but which actually tear the skin on removal. The book Kashrus by Rabbi Lipschutz has a list of non-kosher and kosher fish that was prepared by Dr. Atz, who was an icthiologist at the Museum of Natural History in New York City. The list of non-kosher fish is shown below, it is much shorter than the list of kosher fish. But if a fish that one is not certain about is under discussion, one should actually look for the removable scales and check with an appropriate religious authority. And all other non-fish marine animals, including mammals, crustaceans, and molluscs are also prohibited. The list of non-kosher fish that I have is: Alligator gar Alligatorfishes American eel Angel sharks Anglers Armored gurnards Australian eel Billfishes Black durgon Blenny Blowfishes Boxfishes Brotulas Bullhead Burrfishes Butterfly rays Butter jew Buttersnoek Cabezon Catfishes Channel catfish Chimaeras Clingfishes Cockscombs Conger eel Cowfish Cusk-eels Cutlassfishes Doctorfish Dogfish Dragonets Eaglerays Eels Eelpout Electric Rays Elephantfishes European eel European turbot Filefishes Five-bearded rockling Flying gurnards Fringeheads Frogfish Frostfishes Fugu Galaxias Gars Goby Goosefish Giisefusges Grayfish Guitarfishes Gunnel Hairtail Icefish Inanga Japanese eel Jollytail Kalas Kelpfishes Kihikihis Kingklip Klipfishes Kokopus Lae Lampreys Leatherback Leatherjackets Lings Lumpfish Lumpsuckers Mako shark Mantas Marlin Maori trout Midshipman Minnow Molas Monkfish Moorish idols Morays Mountain trout Noodlefish Ocean catfish Ocean pout Ocean sunfish Oilfish Paddlefis Pejesapo Pikeblennies Porcupinefishes Pout Prickleback Puffers Queenfishes Ratfish Ray Remora Rockskippers Rocksucker Roughies Silfish Sandfish Sawfishes Scabbardfishes Sculpins Sea catfishes Searaven Sea-squab Shannys Sharks Sharksucker Sharpnose puffers Skate Smoothhounds Snailfishes Spearfishes Spoonbill cat Soupfin shark Stargazers Stingrays Suckerfishes Surgeonfishes Swellfishes Tang Toadfishes Tobies Torsk Triggerfishes Trunkfishes Unicorn fishes Viviparous blenny Walking catfishes Warbonnets Whitebait Wolf-eel Wolfishes Accepted by Conservatives but not by the Orthodox Beluga Sturgeon Swordfish
Try the links in the MadSci Library for more information on Zoology.