Now showing items 1-4 of 4

    • Article

      Growth and survival of bighead carp (Aristichthys nobilis) fry fed at different intake levels and feeding frequencies 

      MH Carlos - Aquaculture, 1988 - Elsevier
      This study was conducted to assess the effect of different levels of dietary intake and feeding frequencies on growth and survival of bigheadcarp, Aristichthys nobilis, fry. The feeding rates consisted of 10%, 20%, and 30% of body weight while feeding frequencies were one, three, and five times daily. Results showed that final weight, final length, and specific growth rate (SGR) differed in relation to feeding rate but not to feeding frequency. Highest values were obtained for fish on the 30% ration and fed once a day. A significant effect of higher feeding rate using lower feeding frequency on growth was manifested in final mean weight and SGR; increasing feeding rate resulted in increased growth.

      Feeding frequency significantly influenced fry survival with highest values observed when fry were fed once or three times per day. Highest survivals were achieved by fry on the 30% ration fed once daily. At higher feeding rates using lesser feeding frequencies better survival was noted. Survival rate had an inverse relationship to feeding frequency, but no overall relationship existed between feeding rate and survival rate.

      Both ration and feeding frequency significantly influenced normalized biomass index (NBI). Highest values were again obtained on the 30% ration and feeding once daily. Higher NBI values were observed with higher feeding rates at lower feeding frequencies. Increasing ration resulted in a corresponding increase in NBI.
    • Article

      Hatchery production of Oreochromis niloticus L. at different sex ratios and stocking densities 

      AM Bautista, MH Carlos & AI San Antonio - Aquaculture, 1988 - Elsevier
      The influence of various sex ratios and stocking densities on hatchery production of Nile tilapia, Oreochromis niloticus L., was studied in land-based (concrete tanks) and lake-based (hapa nets) systems. In both hatchery systems, egg and fry production was maximum at a sex ratio of 4:1 females to males and a density of 4 females per m2.

      Seed production varied significantly among treatments at different periods of the year. In concrete tanks, significantly high seed production of 12.98 and 11.77 eggs and fry per spawner per day was obtained in March and August, respectively. In hapa nets, irrespective of sex ratios, 10.18 seeds per spawner were collected daily in March.

      In relation to the broodstock density in concrete tanks, significantly bigger daily harvests of 13.41 and 13.00 eggs and fry per spawner were produced in late February and March, respectively. In hapa nets, daily harvests of 8.95 and 7.74 eggs and fry per spawner were the highest seed production levels which occurred in April and March, respectively.

      Seed production was significantly higher in concrete tanks than in hapa nets while insignificant differences (P>0.05) were found among sex ratio and broodstock density treatments.
    • Conference paper

      Nursery and grow-out operation for tilapia and carp 

      MH Carlos & CB Santiago - In JV Juario & LV Benitez (Eds.), Seminar on Aquaculture Development in Southeast Asia, 8-12 September 1987, Iloilo City, Philippines, 1988 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Most researches conducted at the Binangonan Freshwater Station of the SEAFDEC Aquaculture Department were directed toward enhancing growth and survival of the young tilapia and carp in the nursery as well as increasing yields in grow-out cages, pens, and ponds. Studies included the culture and evaluation of phytoplankton and zooplankton as feeds of the tilapia and carp fry to fingerlings; determination of protein and amino acid requirements of young Nile tilapia; development of practical dry diets; evaluation of feeding regimes, feeding rates, and feeding frequencies ; and the use of fertilizers in nursery ponds.

      For the grow-out aspect, one of the earliest studies demonstrated the profitability of the monoculture of tilapia in cages which triggered the initial proliferation of tilapia cage culture by the private sector in areas near the Station. Subsequently, supplemental feeds were developed and evaluated; non-conventional feedstuffs were tested as feeds or feed components; and the growth rates of Nile tilapia fingerlings in cages at varying stocking densities were evaluated at three distinct rearing periods covering one year.

      Prior to the successful mass production of bighead carp fingerlings at the Station, studies on polyculture of tilapia, milk fish, and different species of carp were conducted in cages and pens with remarkable results. This led to the technology-verification projects on polyculture at various areas in Laguna Lake. With the availability of freshwater fishponds for research purposes, studies on polyculture in ponds were also conducted.
    • Article

      A review of zooplankton in Philippine lakes 

      F Petersen & MH Carlos - Fisheries Research Journal of the Philippines, 1984 - Fisheries Research Society of the Philippines
      This is a review of zooplankton in Philippine lakes including early and present works. A taxonomic list is given and major species are emphasized.