Ornamental Fish Production and Management

7.1.7 Culture of daphnia

Daphnia are commonly called as water fleas. They are cladocerons. Daphnia inhabits in freshwater ponds and tanks. It feeds on algae, bacteria etc.

Natural collection :

Daphnia can be collected from pools, ditches and any stagnant water bodies. They swims on the water surface before sun rise and after sun rise they go to bottom. Hence Daphnia should be collected during early morning hours. Daphnia can be collected with the help of a scoop net having 100-200 micron mesh.

a) Stock and pure culture

Daphnia can be cultured in mass scale level. To prepare stock and pure culture daphnia should be collected and the sample has to be diluted and taken in a glass beaker. Individual Daphnia is picked with the help of a dropper and placed one in each tube containing 10 ml of filtered freshwater. Daphnia is fed with yeast or groundnut oil cake at 200 ppm daily. These tube cultures are transferred to 1 litre jar and feeding is continued. After 5-6 days, the jar culture is inoculated in mass culture tanks.

b) Mass culture

Depending on the requirements, Daphnia is cultured in 500 to 20,000 litre capacity cement or plastic tanks. The culture tanks is thoroughly cleaned and filled with filtered freshwater. Before starting a mass culture, medium is prepared as follows :

Medium preparation :

Slurry is prepared by adding 10 kg of chicken droppings, 5 kg of groundnut oil cake and 2.5 kg of single super phosphate in 250 litre freshwater. Continous aeration is given for 3 days for the escape of obnoxious gases, fermentation and release of nutrients. After 3 days the slurry is used as fertilization solution in the mass culture tanks. In the mass culture tanks, the medium is added at 3 to 4 ml per litre of water regularly for 3 to 4 days. On 4th day, Daphnia is inoculated at 50 individuals per litre. In about 7 days, Daphnia multiplies and density reaches from 10,000 to 25,000 individuals per litre. The Daphnia is harvested using 100-200 micron mesh scoop net in the early morning or late evening when they are on water surface. The Daphnia is washed thoroughly and fed to fish fry.

 Moina culture and Brachionus culture :

Culture of monia and brachionus are similar as that of Daphnia culture. Inoculation is done with respective live foods.