It is narrated from Sayyiduna Jabir (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said regarding the sea: Its water is pure and its dead (fish) is lawful.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 15012
Hadith Gradingحکم دارالسلام:حديث صحيح، وھذا إسناد حسن