In Jorge Luis Borges' Book of Imaginary Beings, Bahamut is a beast of Arabic mythology "altered and magnified" from Behemoth. In Arabic myth, Bahamut is a giant fish, described as so immense that a human cannot bear its sight; "[a]ll the seas of the world, placed in one of the fish's nostrils, would be like a mustard seed laid in the desert."
Borges cites one Muslim tradition that describes Bahamut as a fish floating in a fathomless sea. On the fish is a bull called Kujata, on the bull, a ruby mountain; on the mountain, an angel; over the angel, six hells; over the hells, earth; and over the earth, seven heavens. Another tradition places the earth's foundation on water, the water on a crag, the crag on a bull's forehead, the bull on a bed of sand, the sand on Bahamut, Bahamut on a stifling wind, and the wind on a mist; what is beneath the mist is unknown. In a similar telling of the hierarchy, Bahamut supports a layer of sand, on which stands a giant bull, on whose forehead rests a mountain of rock which holds the waters in which the earth is located.
According to Borges, Bahamut is the giant fish that Isa (Jesus) beholds in the 496th night of the One Thousand and One Nights. Bahamut in this telling is a giant fish swimming in a vast ocean. It carries a bull on its head; the bull bears a rock, and above the rock is an angel who carries the seven stages of the earths. Beneath Bahamut is an abyss of air, then fire, and beneath that a giant serpent called Falak.
Upon seeing Bahamut, Isa passes into unconsciousness:
At this sight Isa fell down aswoon, and when he came to himself, Allah spake to him by inspiration, saying, 'O Isa, hast thou seen the fish and comprehended its length and its breadth?' He replied, 'By Thy honour and glory, O Lord, I saw no fish; but there passed me by a great bull, whose length was three days' journey, and I know not what manner of thing this bull is.' Quoth Allah, 'O Isa, this that thou sawest and which was three days in passing by thee, was but the head of the fish; and know that every day I create forty fishes like unto this.'
Borges cites the idea of Bahamut as part of a layered cosmology as an illustration of the cosmological proof of the existence of God, which infers a first cause from the impossibility of infinite prior causes. He also draws parallels between Bahamut and the mythical Japanese fish Jinshin-Uwo.
Bahamut appears infrequently in popular culture. In the popular Dungeons & Dragons role playing games and Final Fantasy series of video games, Bahamut makes recurring appearances as an extremely powerful platinum dragon. Although the character's name is clearly derived from the mythological Bahamut, the two appear to share no other similarities.