I am fascinated by agnipurana, sanskrit and hinduism. However, this translation is very liberal. Expect surprises!
Chapter Two. The Fish Incarnation
Vasishtha said: "Tell us about the incarnations of vishnu, and repeat to us the agnipurana that vishnu narrated to you"
Agni said: "O vasishtha, I will first tell you about the matsyaavataara (incarnation as a fish). Listen carefully. The lord takes these incarnations to fight and defeat evil and protect the good people. Towards the end of a bygone age, there was a lot of destruction (naimittika pralaya). O saint, at that time the all the worlds were immersed in water. At that time, manu the son of vivasvaana was doing penance for salvation and liberation.