Comparative Growth of Diploid and Triploid Asian Catfish Clarias macrocephalus in Thailand |
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Authors: | Arlo W. Fast Thanit Pewnim Rathaya Keawtabtim Rungarun Saijit Franklin T. Te Renu Vejaratpimol |
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Affiliation: | Hawaii Institute of Marine Biology, University of Hawaii at Manoa, P.O. Box 1346, Kaneohe, Hawaii 96744 USA;Department of Chemistry, Faculty of Science, Silpakorn University, Nakorn Pathom 73000, Thailand;Hawaii Institute of Marine Biology, University of Hawaii at Manoa, Kaneohe, Hawaii USA;Department of Biology, Silpakorn University, Nakorn Pathom, Thailand |
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Abstract: | Wild caught Asian catfish were spawned manually following HCG injection, and a portion of the eggs were subjected to cold-shock at 4 C for 15 min within 2-min post-fertilization. Nuclear diameter measurements of cold-shocked fish revealed that 96% were triploids (3N), while non-shocked fish were all diploids (2N). During larval and fry culture (first 26 d), triploid fish mortality was =50%, while diploid mortality was =25%. Following 8-mo culture in tanks at three stocking densities, triploid fish survival was significantly greater ( P < 0.05), than diploids, with 84.0% and 57.3%, respectively. Triploid live weight was also significantly greater than diploids, with 69.2 and 45.9 g averages, respectively. Ninety-two percent of diploids had welldeveloped gonads after 8 mo; whereas none of the triploids had mature gonads. Gonads were undifferentiated with 31% of the triploids. These sexually undifferentiated fish had greater growth rates than male or female triploids, and greater growth than all diploids. Carcass weight (gutted) of triploids was 95.8% of live weight, compared with 92.5% for diploids. Lastly, triploids had very few deformities compared with diploids, with 1.3% and 17.6%, respectively. Deformities included curved spines, and humped backs just posterior of the head. |
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