MORTALITY REDUCTION AND ENHANCED GROWTH OF MILK FISH "Chanos chanos" IN FINGERLING PRODUCTION AND OCEAN CAGE GROW OUT, USING HIGH REACTIVE MODIFIED MAGNESIUM HYDROXIDE "AQUA-Cal+".

Milk fish "Chanos chanos" are a major food fish for many Asian countries. Milk fish are grown from fry to fingerlings in shallow brackish ponds throughout the Philippines, Taiwan and Indonesia. The big problem in these ponds is mortality due to poor water quality and predation, mortality rates can be in excess of 50% causing financial loss to the farmer. In these trials we wanted to investigate the effect of treatment of the water using a water conditioner "AQUA-Cal+" on mortality, productivity and subsequent grow out in marine cages.

A 12 week trial in two 4 hectare ponds was arranged with Seamagic Digos Davao Philippines. These ponds where earthen ponds with no aeration and depths of about 0.3M. The calculated dosage of AQUA-Cal+ was 100ppm (1000kg) throughout the grown out period in this case 12 weeks. Both ponds where filled with seawater directly from Digos gulf, Pond A was treated with 83kg p.w. of AQUA-CAL+ while Pond B was not, both ponds where allowed to stabilize for 7 days. After 7 days Milk fish fry where added at a rate of 250,000 in each pond. Normal feeding procedures were followed in both ponds. Pond A continued to get a weekly treatment of 83kg p.w. AQUA-Cal+ all other conditions remained the same for both ponds.

Fingerlings where then transferred to sea cage grow out 15,000 per cage

The cage containing the fish grown in the AQUA-Cal+ treated pond reached market size 2 weeks before the other cage.

Trials are ongoing with a number of species including milk fish, prawns, tilapia, silver perch and trout. In all cases similar increases are being observed with some additional benefits being observed such as elimination of sludge in pond bottoms, increased DO and reduction in H2S level.