The Swordfish, sturgeon, sharks, eels & lump-fish etc. are never kosher. ... Shellfish, crustaceans, Mammals, such as seals, dolphins & whales etc. are not kosher. The dolphin fish "mahi-mahi" is a kosher fish. Swimming creatures i.e. sea horses, squid, lobsters etc. are not considered fish & are not kosher. read more
Shopping for kosher fish can be fairly confusing. The biblical injunction – only fish with fins and scales – sounds fairly straightforward. And it is easy to remember that shellfish – including such popular items as lobster, shrimp and mussels – are verboten for the kosher-observant. read more