Give merits and demerits of fish culture.

Merits:

1. Desired Fish: Economically important desired fishes are made available.

2. Smaller Area: A large number of fishes are raised in a small area.

3. Fish Seeding: Fishes are made to breed in different seasons.

4. Mortality: There is little mortality in the younger stages of the fishes.

5. Improvement: Through selective hybridisation, yield and quality of fishes are improved.

Demerits:

1. Genetic Loss: Only some selected high yielding and economically important breeds are reared. Other breeds and varieties are lost.

2. Threat to Biodiversity: Other forms of aquatic organisms are being ignored. Even natural waters are being seeded with economically important fishes so that natural biodiversity has come under threat.