It is narrated from Hazrat Abu Huraira (may Allah be pleased with him) that a man asked the Holy Prophet (peace and blessings be upon him): "We travel by sea and carry only a little water for drinking. If we use it for ablution, we will remain thirsty. Can we perform ablution with sea water?" The Holy Prophet (peace and blessings be upon him) replied: "The water of the sea is purifying and its dead (fish) is lawful."
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 8735
Hadith Gradingحکم دارالسلام:حديث صحيح، وقد اختلف فى إسناد هذا الحديث