Q: I want to know is it permissible to eat lobster, prawn, crab in Islam? If it is permissible, then in which categories our beloved Nabi (Sallallahu Alayhi Wasallam) ate in his life?
A: According to the hanafis all that which comes under fish (Pisces) is consumable.
And Allah Ta’ala (الله تعالى) knows best.
( ولا ) يحل ( حيوان مائي إلا السمك ) (الدر المختار 6/306)
تكملة فتح الملهم 3/513