Question

Short note on hill stream fishes?3mark

Answer 1

1. Origin of Hill Stream Fishes 2. Environmental Conditions of the Hill Stream 3. Families 4. Adaptive Modification.

A number of fishes have migrated from sluggish waters of the lower streams to colonize in the torrential waters of the upper streams. These migrations were chiefly in search of food and the shelter from the predators. Upon reaching the new habitat, these fishes adapted themselves through a number of structural modifications and called the hill stream fishes.

Origin of Hill Stream Fishes:

Hora (1922) suggested two views regarding the origin of hill stream fishes.

According to first view, the fishes living in the hill streams reached accidently. The second view suggests that from low land streams, fishes migrated to upstream in search of food and protection from the predators which were more numerous in low land waters. On reaching the new habitat, they gradually specialized to survive in new habitat. The second hypothesis appears to be more correct.

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