Juvenile blue swimming crab, Portunus pelagicus were reared over 31 days in two different systems namely recirculating aquaculture system (RAS) and conventional aquaculture system (CAS) to evaluate the water quality parameters, growth, and its body composition. The juvenile crab, weighing of 0.95 ± 0.18 g and stocking was at 40 crabs m -2 and fed twice per day with a commercial shrimp pellet. During the experimental time, significantly (P <0.05) increment in dissolved oxygen (DO) (6.42 ± 0.13), low level of ammonia-nitrogen (0.04 ± 0.10) and nitrite-nitrogen (0.04 ± 0.10) were recorded in RAS than conventional aquaculture system (CAS) (DO: 5.99 ± 0.24;. The carapace width, weight gain and specific growth rate (SGR) were significantly (P <0.05) higher in RAS. Protein content (22.65 ± 0.11%) in crab also were significantly (P <0.05) higher in RAS compared with crab protein (21.41 ± 0.12%) cultured in CAS. Although the survival rate was slightly higher in the juveniles reared at CAS, however it was not significantly different comparing with the individuals reared at RAS. The results strongly suggested that the use of RAS may improve the growth performance and maintain the better water quality for the crabs in captivity.
ABSTRAKKetam juvenil renang biru, Portunus pelagicus telah dipelihara selama 31 hari dalam dua sistem berbeza iaitu sistem akuakultur udara berulang (RAS) dan sistem akuakultur konvensional (CAS) untuk menilai parameter kualiti air, tumbesaran dan komposisi badan. Ketam juvenil seberat 0.95 ± 0.18 g dan penstokan adalah pada 40 ketam m -2 dan diberi makan dua kali sehari dengan pelet udang komersial. Semasa masa uji kaji percubaan, peningkatan (P < 0.05) dengan ketara oksigen terlarut (DO) (6.42 ± 0.13), tahap rendah ammonia-nitrogen (0.04 ± 0.10) dan nitrit-nitrogen (0.02 ± 0.07) direkodkan dalam RAS daripada konvensional sistem akuakultur (CAS) (DO: 5.99 ± 0.24;. Lebar karapas, pertambahan berat dan kadar pertumbuhan khusus (SGR) adalah ketara (P < 0.05) lebih tinggi dalam RAS. Kandungan protein (22.65 ± 0.11%) pada ketam juga adalah ketara (P < 0.05) lebih tinggi pada RAS berbanding dengan protein ketam (21.41 ± 0.12%) yang dikultur dalam CAS. Walaupun kadar kemandirian adalah lebih tinggi dalam juvenil yang dipelihara dalam CAS, walau bagaimanapun, ia tidak berbeza dengan ketara berbanding dengan individu yang dipelihara dalam RAS. Keputusan menyarankan bahawa penggunaan RAS boleh meningkatkan prestasi tumbesaran dan mengekalkan kualiti air yang lebih baik untuk ketam dalam kurungan. Kata kunci: Kemandirian; pertumbuhan; Portunus pelagicus; sistem akuakultur konvensional (CAS); sistem akuakultur udara berulang (RAS)
The experiment was conducted to determine the suitability of using scad fish, shrimp and common squid for the direct and indirect application as diets for the juvenile rearing of the blue swimming crab. A total of 54 crab juveniles with an initial weight of 2.46 ±0.94 g were randomly stocked in triplicate at 6 crabs per 60 l tank (0.26 m²) experimental units and fed twice daily with three different types of feed namely scad fish, squid tissue and frozen shrimp for a period of 31 days. At the end of the trail, ammonia and nitrite-nitrogen compound were significantly higher in shrimp fed group. It is found that final body weight (g) of was significantly higher when fed with squid, however no significant differences were noticed between scad fish and shrimp fed groups. The whole body proximate composition was similar in all the diet fed individuals except the level of lipid which was higher in squid compared to scad fish and shrimp. Significantly (p<0.05) better food conversion ratio (FCR) was observed in juvenile crab fed with squid even though scad fish possessed the highest crude protein of 83.33%. Overall, the results suggested that squid meal could be recommended for juvenile culture. Hence, squid meal may be incorporated in crab artificial diet as protein source to attain better survival and growth.
Aim :Methodology :
Results :Interpretation :Cannibalism remains a limiting factor during the nursery culture of crabs. This study was undertaken to improve the rearing techniques by investigating the impact of bottom substratum on crablet survival and growth. The knowledge gained from the research will be useful for the communal seed culture and development of crab farming, which are important factors regarding farmers' job stability in the future.Blue swimming crab, (first settled (C1 crabs); initial average weight and SD of 0.02 ± 0.01g) were cultured in glass aquarium (90 x 44 x 34 cm) and their survival and growth were assessed after 22 days of culture in four types of substratum such as control (none), sand, soil, or sand + soil. All treatments had 25 juvenile crabs, each of which was triplicated. Feeding was done twice a day (9 am and 5 pm) to apparent satiation.Survival of early juvenile crabs cultured with sand was substantially higher at 65.33 ± 6.11% than those cultured with soil, sand + soil or control at 29.33 ± 10.07%, 28.00 ± 8.00%, and 21.33 ± 6.11%, respectively. Growth performance (such as final weight, weight gain and specific growth rate) of the early juvenile of in all treatments were not significantly different (p>0.05).Overall, the best survival was achieved with sand substratum and can be recommended as a mean of reducing cannibalism during the early nursery rearing of blue swimming crab juveniles u n d e r c a p t i v e c u l t u r e conditions.
Portunus pelagicus P. pelagicus
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