Surah Al-Ma'idah (Chapter 5) Verse 96:
Lawful to you is game from the sea and its food as provision for you and the travelers, but forbidden to you is game from the land as long as you are in the state of ihram. And fear Allah to whom you will be gathered.
From my understanding it can be derived that almost all sea-food is halal but there are few exceptions to be avoided according to different madhabs
Originally Posted by http://www.albalagh.net/qa/sea_food_madhahib.shtml
I hope this clears your doubts.
And Allah (s.w.t.) knows best.