“Then the Philistines took the ark of God and brought it into the house of Dagon and set it up beside Dagon. And when the people of Ashdod rose early the next day, behold, Dagon had fallen face downward on the ground before the ark of the LORD. So they took Dagon and put him back in his place. But when they rose early on the next morning, behold, Dagon had fallen face downward on the ground before the ark of the LORD, and the head of Dagon and both his hands were lying cut off on the threshold. Only the trunk of Dagon was left to him. This is why the priests of Dagon and all who enter the house of Dagon do not tread on the threshold of Dagon in Ashdod to this day. The hand of the LORD was heavy against the people of Ashdod, and he terrified and afflicted them with tumors, both Ashdod and its territory. And when the men of Ashdod saw how things were, they said, “The ark of the God of Israel must not remain with us, for his hand is hard against us and against Dagon our god.”- 1 Samuel 5:2-7
Dagon was the god of crop fertility for the Philistines. He was second in command after the supreme god, El. Dagon was represented by half-man and half-fish. He was the father of the god Baal. Dagon is also created with inventing the plough. When Dagon fell before the Ark, it was a sign to the Philistines that the Israelites’ god is more powerful than theirs. The Philistines recognized this sign eventually.
Not only did the Philistines believe in Dagon, the Babylonians did as well. The Babylonians had a myth that a being emerged from the Erythraean Sea who was part man and part fish and thus adopted the deity into their culture in their earliest days in history. There have also been discoveries of the fish-god in the sculptures found in Nineveh, Assyria.