Question: why are eels not kosher?
Answer: Eel is not a kosher food. Any seafood like fish and snails are only kosher if they have fins and scales, hence the result is that snails, crab, lobster, and EEL, are all unkosher, so too any fish that doesn't carry those two specifications. So salmon, trout, carp, and that kinda stuff are all kosher.