Now showing items 1-5 of 5

    • Article

      Breeding and larval rearing of the rabbitfish, Siganus guttatus (Bloch) 

      JV Juario, MN Duray, VM Duray, JF Nacario & JME Almendras - Aquaculture, 1985 - Elsevier
      Females of Siganus guttatus reared to sexual maturity in canvas tanks were induced to spawn by using human chorionic gonadotropin (HCG, Ayerst) at 500 IU/fish or about 2 IU/g body weight. The amount of HCG used depended on the initial mean egg diameter; the smaller the diameter, the more HCG was used. Fish with oocytes characterized by germinal vesicle migration (mean egg diameter ≥ 0.47 mm) spawned without HCG injection. Fertilization and hatching rates for both treated and untreated fish were more than 90%. The larvae were reared to metamorphosis using rotifers from day 2–17, rotifers + newly hatched Artemia nauplii from day 18–20 and rotifers + newly hatched Artemia nauplii + artificial feed from day 21–35. In addition, Isochrysis galbana was introduced to the rearing tanks from day 1–10 and Chlorella sp. and/or Tetraselmis sp. from day 1–35. Survival rates of larvae tended to be lower as the broodstock became older.
    • Article

      The effect of thyroxine on the larvae and fry of Sarotherodon niloticus L. (Tilapia nilotica) 

      JF Nacario - Aquaculture, 1983 - Elsevier
      Effects of thyroxine (T4) (0.1 ppm; 0.3 ppm; 0.5 ppm) on Sarotherodon niloticus L. yolk sac larvae were studied after 4 weeks of treatment from hatching. T4 at 0.5 ppm accelerated yolk resorption but did not significantly increase growth after the first week of treatment. Increase in length and in weight among fry treated with T4 at 0.1 ppm and 0.3 ppm was significant after the fourth week. T4 at 0.1 ppm increased significantly the length of the pectoral fin; but at 0.3 ppm and 0.5 ppm caused abnormal shapes in the pectoral fins as well as lordosis and scoliosis. T4 reduced pigmentation in treated yolk sac larvae for 3 days only and caused thickening of the epidermis in both treated yolk sac larvae and fry. Thyroid follicles were absent in the yolk sac larvae but present in the fry.
    • Article

      Induced breeding and larval rearing experiments with milkfish Chanos chanos (Forskal) in the Philippines 

      JV Juario, MN Duray, VM Duray, JF Nacario & JME Almendras - Aquaculture, 1984 - Elsevier
      Salmon pituitary homogenate was used alone or in combination with human chorionic gonadotropin, to induce spawing in captive and wild adult milkfish at ambient temperature (26–30°C) and salinity of 34%.. Healthy or slightly injured females having oocytes with a minimum mean diameter of 0.66 mm could be induced to spawn in captivity using a total dose of 20 mg SPH/kg + 3000 IU HCG/kg given in two injections. Badly injured females did not respond readily to the hormone and required more than two injections to induce ovulation.

      Milkfish larvae were reared successfully to metamorphosis using only Chlorella-fed rotifers during the first 10 days. Survival rates were greatly improved when, aside from Chlorella and Chlorella-fed rotifers, Isochrysis galbana and Tetraselmis chuii were added to the rearing tanks.
    • Article

      Induced spawning of sea bass, Lates calcarifer, and rabbitfish, Siganus guttatus, after implantation of pelleted LHRH analogue 

      B Harvey, JF Nacario, LW Crim, JV Juario & CL Marte - Aquaculture, 1985 - Elsevier
      Captive Lates calcarifer broodstock at Tigbauan, Iloilo (Philippines) were implanted with cholesterol-based pellets of the LHRH analogue D-Trp6-desGly10-LHRH ethylamide or D-hArg(Et2)6, Pro9-NHet-LHRH at doses between 9.0 and 23.5 μg/kg body weight. In May, one of ten LHRH-treated females released partially hydrated ova into the tank 4 days after implantation. In July, at least one (and probably four) of five LHRH-treated females spawned in the tank 2 days after implantation; 2.6 million hatchlings were collected. In August, both LHRH-treated females spawned in the tank 2 days after implantation; 978 000 hatchlings were collected. None of the sham-operated control fish spawned in any of the experiments.

      Captive Siganus guttatus broodstock implanted with silastic-based pellets of the LHRH analogue D-Nal (2)6LHRH spawned 1–2 days earlier than sham-operated controls.
    • Conference paper

      Releasing hormones as an effective agent in the induction of spawning in captivity of sea bass (Lates calcarifer) 

      JF Nacario - In JW Copland & DL Grey (Eds.), Management of Wild and Cultured Sea Bass/Barramundi (Lates calcarifer): proceedings of an International Workshop held at Darwin, N.T., Australia, 24-30 September 1986, 1987 - Australian Centre for International Agricultural Research
      A study was conducted to evaluate the effectiveness of luteinising-hormone releasing hormones in the induction of spawning of Lates calcarifer using different administration techniques: pellet implantation, Chinese analogue and osmotic pump implantation.