In the beginning, before the sun rose for the first time, the great god Ra sailed his barque across the dark waters of Nun, the primordial ocean that surrounded the world. The barque was the solar boat, the vessel that carried light through the underworld each night and back into the sky each dawn. But the journey was perilous. In the depths lurked Apep, the serpent of chaos, a demon who sought to swallow the sun and plunge the world into eternal darkness. To guard against this threat, the gods placed two sacred fish at the prow of the boat. Abtu, the golden fish, swam at the front as the lookout, while Anet, the red fish, swam alongside as the defender. Together they formed the first line of protection for the most important voyage in existence, the daily journey that kept maat, the divine order, alive.

Each morning, as Ra's barque rose into the eastern sky, the golden fish sprang into being in the turquoise waters, a signal that the sun had survived the night. Abtu's appearance meant that the Evil One had fallen, that chaos had been defeated once more. The Ogdoad, the eight primordial deities who existed before creation, sang of Abtu announcing the approach of the wenti-snake, giving the god Horus, the falcon-headed protector of divine order, time to fix his spear into the enemy's body. In the house of Neith, the ancient goddess of war and weaving, the fish's screaming voice echoed as a warning that danger approached the boat. Abtu was not merely a passenger but an active participant in the war against chaos, the first sentinel that cried out when the serpent stirred.

The fish was so sacred that the greatest goddess of Egypt chose to wear its form. Isis, the wife of Osiris and mother of Horus, transformed herself into Abtu, the Great Fish of the Abyss, to work her magic in the hidden depths. In this shape she moved through the dark waters where the pieces of her murdered husband's body had been scattered by his jealous brother Set, the god of storms and violence. The city of Oxyrhynchus, whose Greek name means "sharp-nosed fish," held a special connection to this aspect of the myth, for there the fish that swallowed Osiris's phallus was identified with the oxyrhynchus species, and Isis in her fish form was linked to the sacred penis-swallower. The fish cult spread across Egypt, and the great city of Abydos took its name from Abtu, becoming the centre of Osiris's worship and the burial place of the earliest kings, a city where the west, the realm of the dead, and the sacred fish met in one holy location.

Beyond the grand myths of gods and cosmic battles, Abtu lived in the daily lives of ordinary Egyptians. The fish was an edible species, most likely a type of tilapia, and it appeared in medical recipes and magical protection spells. Physicians prescribed parts of the fish for ailments, and protective incantations called upon its power to ward off evil. This practical sacredness was typical of Egyptian religion, where the divine and the everyday were never fully separated. Abtu was not only the guardian of the sun god but also a helper in the home, a creature whose body could heal and whose name could protect. Archaeologists have found beautiful glass fish from Amarna dating to around 1800 BCE, delicate artefacts that may represent the sacred fish in temple offerings or household shrines, tangible proof that Abtu was honoured in both palace and village.

The name Abtu outlived the pharaohs and their temples. It remained the Egyptian word for the west, the direction where the sun set and died each day, passing into the dark underworld where the dead walked. Every evening, as Ra's barque sank below the horizon, Abtu was there, leading the way into the night. The city of Abydos, the Abdu of later ages, kept the fish's name for thousands of years, and pilgrims continued to flock there to honour Osiris and the mysteries of death and rebirth. In the end, Abtu is the eternal sentinel, the small golden creature that stands between order and chaos, between light and darkness, between the living world and the land of the dead.