'The Hildebrand Rarity' (1960) by Ian Fleming

Bond is on an assignment in the Seychelles Islands; through Fidèle Barbey, his influential and well-connected local contact, he meets an uncouth American millionaire, Milton Krest, who challenges the two to aid him in the search for a rare fish, the Hildebrand Rarity. Bond, Barbey, Krest and his English wife, Elizabeth, set off aboard Krest's boat, Wavekrest, in search of the fish. During the journey, Bond learns that Milton verbally and physically abuses everyone around him, especially his wife—whom he punishes with the use of a stingray tail he dubs "The Corrector". Krest finds the Hildebrand Rarity and kills it—along with many other fish—by pouring poison into the water. Wavekrest sets sail for port. Along the way Krest gets very drunk, insults Bond and Barbey and tells his wife he will beat her again with the stingray tail. Later that night, Bond hears Krest choking; investigating, Bond finds that Krest has been murdered—apparently by having the rare fish stuffed down his throat. So as not to be entangled in a murder investigation, Bond throws Krest overboard and cleans up the scene of the crime, making it look as though Krest fell overboard after one of the ropes holding his hammock broke: Bond suspects both Barbey and Mrs. Krest, but is unsure which is responsible.