It was narrated that Mughirah bin Abu Burdah, who was from the tribe of Banu 'Abdud-Dar, said that:He heard Abu Hurairah say: "A man came to the Messenger of Allah and said: "O Messenger of Allah, we travel by sea and carry a small amount of water with us. If we use it for ablution, we will become thirsty. Can we perform ablution with seawater?' The Messenger of Allah said: 'Its water is a means of purification, ad its dead meat is permissible. (i.e. the fish found dead in the sea)

English translation · Sunan Ibn Majah