Question

Trout that had the pituitary gland removed do not acclimate when moved to freshwater, and die. To prevent this effect, it would be sufficient to inject these fish with:

1. cortisol

2. Growth hormone

3. Prolactin

4. Cortisol and growth hormone

5. Cortisol and prolactin

Briefly explain your reasoning.

Answer 1

Prolactin is known as the freshwater adaptation hormone. It increase the active ion uptake and decrease the water and iron permeability by the osmoregulatory surfaces such as skin, and gills of fresh water fish. Development and proliferation of the freshwater-type chloride cell in fresh water fish for accimilation and osmoregulation is maintained by prolactin. Prolactin helps the fish for freshwater adaptation. Removal of pituitary gland can cause lower plasma ion levels which can be regulated by injecting prolactin in the fresh water fish.

The answer is 3. Prolactin.