Give merits and demerits of fish culture.

Merits. 1. Economically important desired fishes are made available.
2. A large number of fishes are raised in a small area.
3. Fishes are made to breed in different seasons.
4. There is a little mortality in the younger stages of the fishes.
5. Through selective hybridisation, yield and quality of fishes are improved.
demerits1. Only some selected high yielding and economically important breeds are reared.
2′ Fish culture is a threat.to biodiversity, since other forms of aquatic organisms are being ignored. Even natural waters are-being seeded with economically important fishes; this too is affecting the natural biodiversity of the water bodies.