Milagros R. de la Peña

Antibacterial activity of tilapia Tilapia hornorum against Vibrio harveyi

Abstract Disease due to luminous Vibrio has been a major problem of the shrimp industry. Different technologies have been introduced to control the disease. One of the techniques reported to work against luminous bacteria in the Philippines is the green water culture system (or finfish–shrimp integrated culture system). A green water culture system is an innovative technique wherein shrimp are cultured in water collected from a pond where tilapia or other fish species are grown. In some cases, the fish are cultured in an isolated net pen inside the shrimp culture pond. This study clarifies the effect of one component of the green water culture system, the presence of all male tilapia ( Tilapia hornorum ) on luminous bacteria Vibrio harveyi . Results showed that stocking tilapia at a biomass not lower than 300 g/m 3 efficiently inhibited the growth of luminous bacteria in shrimp (biomass=80 g/m 3 ) rearing water without the growth of microalgae.

Investigation of some components of the greenwater system which makes it effective in the initial control of luminous bacteria

Abstract Two components of the greenwater system, the tilapia water and Chlorella , were investigated separately for their effect on the population of luminous bacteria. For the investigation of tilapia water, Tilapia hornorum was stocked at different biomasses 0, 1 and 3 kg/10 m 3 . Vibrio harveyi was introduced to the tanks at a final concentration of 10 3 cfu/ml. Luminous bacteria could not be detected in tanks stocked at 3 kg/10 m 3 from day 4 to day 6, and on day 6 in tanks stocked at 1 kg/10 m 3 . The bacteria could still be recovered in tanks without tilapia on day 6. Investigation of the effect of chlorella alone on V. harveyi was undertaken using sterile flasks containing 500-ml autoclaved seawater provided with aeration. In treated flasks Chlorella was added, whereas no Chlorella was added to control flasks. No luminous bacteria were recovered on day 2 and day 3 in flasks with Chlorella , while those without the microalgae still harboured luminous bacteria at day 3.

The effect of micro algal diet and rearing condition on gonad maturity, fecundity and embryonic development of the window-pane shell, Placuna placenta Linnaeus

This work was funded by the Fisheries Sector Program (FSP) of the Department of Agriculture, Philippines (Project Code: 6955-100-60) and the Aquaculture Department of the Southeast Asian Fisheries Development Center (SEAFDEC).