Not ALL seafood is halaal - fishes are fine. You can eat flounder, scrod, tuna, all the fishes of sea and stream. But bottom-feeders (shellfish) are haraam - clams, shrimp, lobster, crabs. Basically the same I think as Kosher rules.
I thought actually that Halaal foods and the rules came from the same set of rules as for Kosher. But there are rules like never mix meat and dairy in order to be kosher. Why is this not a rule for Halaal?
