The fish live in the sea for three years. They swim far away from land. How do they find their way back? These fish have a wonderful sense of smell. They always remember the smell of their journey to the sea easily, because the river was flowing to the sea and carried them there. Most of them live, and keep swimming toward their pools. As soon as they reach a pool, the females lay their eggs. They lay their eggs near the edge of the water and cover them with sand. Soon the eggs hatch and the pool is full of small fish, getting ready for the long journey out to the sea.

The above paragraph talks about _____________________.