How Do Oscar Fish Mate?

The mating ritual of oscars begins with a pair of fish engaging in such activities as nipping, jaw locking, chasing each other around, picking up sand in their mouths and relocating it elsewhere in the tank. Once the oscars decide to mate with each other, they begin to prepare an area for their eggs.

Oscars generally select a large flat surface for their eggs, and they each clean the area vigorously with their lower jaws until it is spotless. If a flat rock is not present, oscars dig down through the sand until they reach the bottom of the tank and lay their eggs there. Once they prepare a flat space, the female begins swimming back and forth over the prepared area. The sex organs of the male and female then protrude.

Eventually, the female begins laying small white eggs. The female does not lay all the eggs at once. Instead, she lays a small portion of them before the male swims over the eggs and fertilizes them. The female then proceeds with the egg laying. Once the oscars lay and fertilize the eggs, they fan water over the eggs with their fins in order to oxygenate them.