After eating a salty fish dinner you are very thirsty for plain water, a condition described as

Hypernatremia

Hypernatremia is a condition that infers too much salt and less water in the body, which could result to dehydration where the person is thirsty for plain water after eating a salty fish. There are sensors in the body that could detect saltiness of the blood and this sends signals to the brain that the body needs water to dilute the salt and balance the fluids in the cells. Therefore, making the person feel thirsty for water.

1. is geographic distribution

2 is increasing complexity

3 is transitional forms