Freshwater aquaculture

Practical 3 - Weed fish and predatory fish

3.2. Eradication of weed fish
Weed and predatory fish can be eradicated by use of toxins of plant origin or by the use of chemicals. Use of pesticides is not recommended since they are not environment friendly. Teh following material can be used to eradicate weed and predatory fish.

Toxins of plant origin

• Mahua oil cake: applied @ 200-250 ppm
• Derris root powder applied @1-10 ppm
• Jaggery @1%

Chemicals

• Bleaching powder @175 kg + Urea 100 kg. Per hectare

Work-out

• Calculate the amount of mahua oil cake to be applied @ 250 ppm to eradicate weed fish in the following culture systems
• Pond 20m x 50 m, depth 1.5 m
• Well: radius 25 m depth 10 m
• Tank: 0.5 ha.