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    • Technical Report

      Artificial fertilization of eggs and early development of the milkfish Chanos chanos (Forskal) 

      H Chaudhuri, JV Juario, JH Primavera, R Mateo, R Samson, ER Cruz, EO Jarabejo & JT Canto Jr. - In Induced spawning, artificial fertilization of eggs and larval rearing of the milkfish Chanos chanos (Forskal) in the Philippines, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      Series: Technical report / SEAFDEC Aquaculture Department; 4
      Hydrated eggs obtained from a female milkfish were artificially fertilized with the milt collected from a male injected with acetone-dried pituitaries of salmon. The fertilized eggs (1.1 to 1.25 mm in diameter) developed normally in seawater in basins and Petri dishes at a salinity of 30-34 ppt and successfully hatched in 25 to 28½ hours at a temperature of 26.4-29.9°C. The yolk was completely absorbed in about 2½ days and at this period many postlarvae died. A few larvae were reared up to 5 days but all died within 6 days. Effects of feeding the postlarvae from the third day with freshly hatched trochophore larvae of oysters obtained from eggs artificially fertilized in the laboratory could not be ascertained.
    • Article

      Notes on the external sex characters of Chanos chanos (Forskal) spawners 

      H Chaudhuri, JV Juario, R Samson & LB Tiro - Fisheries Research Journal of the Philippines, 1976 - Fisheries Research Society of the Philippines
      In the present study, no visible differences between the sexes of C. chanos with reference to external features such as colouration, shape of head, snout and operculum, presence of tubercles or nasal pores, length, size and shape as well as any roughness in the various fins, could be found. However, the anal region of the mature milkfish (sabalo) exhibits discernible anatomical differences in the male and female. The male has two main openings visible externally: the anterior anus and the posterior urogenital opening at the tip of the urogenital papilla. The female has three main openings instead of two: the anteriormost anus, followed by the genital pore and the urinary pore located posterior to the genital pore at the tip of the urogenital papilla. Internal examinations were also made on both sexes. In ripe sabalo, it is easier to distinguish the sexes since milk oozes out of the urogenital pore by pressing the abdomen of the ripe male fish. Gravid females are identified by their distended abdomens.
    • Article

      Notes on the external sex characters of Chanos chanos Forskal spawners 

      H Chaudhuri, J Juario, Samson R. & R Mateo - SEAFDEC Aquaculture Department Quarterly Research Report, 1977 - Aquaculture Department, Southeast Asian Fisheries Development Center
      In this study, the authors did not find any visible differences between the sexes with reference to external features such as coloration, shape of head, snout and operculum, presence of tubercles or nasal pores, length, size and shape as well as any roughness in the various fins. However, the anal region of the mature milkfish exhibits discernible anatomical differences in the male and female. In the males, there are 2 main openings visible externally. These are the anterior anus and the posterior urogenital opening at the tip of the urogenital papilla. Internally, the vasa deferentia (male genital ducts) from the testes join into a common duct about 5-10 mm from the urogenital pore. The urinary pore opens into this common duct from the dorsal side. In addition, there are 2 small pores situated on each side of the base of the urogenital papilla opening ventrally into the coelom. In the females, there are 3 main openings in the anal region instead of 2 as found in the males. The anteriormost opening is the anus followed by the genital pore. The third opening is the urinary pore which is posterior to the genital pore located at the tip of the urogenital papilla.
    • Article

      Observations on artificial fertilization of eggs and embryonic and larval development of milkfish, Chanos chanos (Forskal) 

      H Chaudhuri, JV Juario, JH Primavera, R Samson & R Mateo - Aquaculture, 1978 - Elsevier
      Hydrated eggs obtained from a female milkfish, Chanos chanos, were artificially fertilized with the milt collected from a male injected with acetone-dried pituitaries of salmon. The fertilized eggs (1.1–1.25 mm in diameter) developed normally in seawater in basins and petri dishes at a salinity of 30–34‰, and successfully hatched in 25–28.5 hours at a temperature of 26.4–29.9°C. The yolk was completely absorbed in about 2.5 days and during this period many postlarvae died. A few larvae were reared up to 5 days but all died on the 6th day. Attempts were made to feed the postlarvae with freshly hatched trochophore larvae of oysters obtained from eggs artificially fertilized in the laboratory.
    • Article

      Use of hormones in breeding cultivated warm-water fishes with special reference to milkfish, Chanos chanos (Forskal) 

      H Chaudhuri & JV Juario - Fisheries Research Journal of the Philippines, 1978 - Fisheries Research Society of the Philippines
      The role of hormones in the controlled reproduction of a few test fishes is well documented. However, information on the mechanisms of endocrine regulation of ovulation in cultivated warm-water fishes is very meagre. Hormones, especially the gonadotropic hormones of piscine origin, are increasingly being used in modern aquaculture to produce the seed of many important cultivated fishes. While chorionic gonadotropin and other exogenous mammalian hormones are used in spawning the channel catfish, fish pituitary hormones are usually needed to induce spawning in the difficult-to-spawn Asiatic carps. In mullets, however, either homoplastic pituitary gland or human chorionic gonadotropin (HCG) or a mixture of HCG and a threshold dose of the former is ordinarily injected to precipitate spawning. Of late, semi-purified salmon gonadotropin (SG-G100) has been used to induce spawning in several species of food fishes. While several marine fishes have been artificially bred by administration of hormones, induced spawning of the milkfish, C. chanos has been tried with little success. The milkfish is a widely distributed food fish extensively cultivated in ponds in Southeast Asia. Recently, significant results have been obtained in spawning mature milkfish captured from the wild by hormone injections. The experiments conducted on induced breeding of milkfish leading to the successful fertilization and hatching of milkfish eggs are briefly described.