Question

how can we say that fish exhibits external fertilization

Answer 1

If the fusion of male and female gametes takes place outside the body, it is called external fertilisation. It usually takes place in aquatic bodies. And yes, fish also reproduce their young ones in the water so the fertilisation takes place outside the body. Thus it is an external fertilisation. Hope this helps!

Answer 2

External fertilization is a kind of fertilization where eggs are released into the environment in order to be fertilized by the male. In this kind of fertilization, a moist, as opposed to dry, environment is necessary. This is true for two reasons: the first reason is that the gametes, which are just reproductive cells, the sperm and eggs, can dry out and become non-functional in a dry environment. The second reason is that a moist environment allows the sperm to move towards the eggs in order to fertilize them.