|Improved techniques for rearing mud crab Scylla paramamosain (Estampador 1949) larvae|
|Nghia, T.T.; Wille, M.; Binh, T.C.; Thanh, H.P.; Van Danh, N.; Sorgeloos, P. (2007). Improved techniques for rearing mud crab Scylla paramamosain (Estampador 1949) larvae. Aquac. Res. 38(14): 1539-1553. dx.doi.org/10.1111/j.1365-2109.2007.01814.x|
|In: Aquaculture Research. Blackwell: Oxford. ISSN 1355-557X, more|
Prophylaxis; Rearing techniques; Water exchange; Scylla paramamosain Estampador, 1949 [WoRMS]; Marine
Scylla paramamosain; rearing techniques; water exchange; micro-algae; larval density; life food density; prophylaxis
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A series of rearing trials in small 1 L cones and large tanks of 30-100 L were carried out to develop optimal rearing techniques for mud crab (Scylla paramamosain) larvae. Using water exchange (discontinuous partial water renewal or continuous treatment through biofiltration) and micro-algae (Chlorella or Chaetoceros) supplementation (daily supplementation at 0.1-0.2 million cells mL-1 or maintenance at 1-2 millions cells mL-1), six different types of rearing systems were tried. The combination of a green-water batch system for early stages and a recirculating system with micro-algae supplementation for later stages resulted in the best overall performance of the crab larvae. No clear effects of crab stocking density (50-200 larvae L -1) and rotifer (30-60 rotifers mL-1) and Artemia density (10-20 L-1) were observed. A stocking density of 100-150 zoea 1 (Z1) L-1, combined with rotifer of 30-45 mL-1 for early stages and Artemia feeding at 10-15 nauplii mL-1 for Z3-Z5 seemed to produce the best performance of S. paramamosain larvae. Optimal rations for crab larvae should, however, be adjusted depending on the species, larval stage, larval status, prey size, rearing system and techniques. A practical feeding schedule could be to increase live food density from 30 to 45 rotifers mL-1 from Z1 to Z2 and increase the number of Artemia nauplii mL-1 from 10 to 15 from Z3 to Z5. Bacterial disease remains one of the key factors underlying the high mortality in the zoea stages. Further research to develop safe prophylactic treatments is therefore warranted. Combined with proper live food enrichment techniques, application of these findings has sustained a survival rate from Z1 to crab 1-2 stages in large rearing tanks of 10-15% (maximum 30%).