Ikrimah narrates from Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) that he said: I bear witness that Sayyiduna Abu Bakr al-Siddiq (may Allah be pleased with him) said: A fish that floats up on the water after dying is lawful for whoever wishes to eat it.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيد والذبائح / 18974