Success Stories In Asian Aquaculture - Library - Network of ...

140 N.T. Phuong and D.T.H. Oanh36.2% have 2–4 ponds, and 6.5% hasve more than 4 ponds. Liem et al. (2008)reported that some large farms may have up to 26 ponds.7.7.2 Key Culture Techniques of Pond CultureThe first striped catfish ponds were built on alluvial deposits along the mainbranches of the Mekong River of good soil quality and plentiful supply of water.Farms are normally designed with fixed supportive systems, such as water supply anddrainage systems, feeding stations, and water pumps. A good farm design mustensure possibility of a high water exchange for ponds, especially at the end of theculture cycle. Pond size is quite similar around 0.4–0.42 ha. Taking advantage of aplentiful water supply, ponds are designed with high water level of 3.6–4 m for highstocking density. Phuong et al. (2004) reported that the average stocking densitiesof striped catfish in pond were was 20.5 fish m −2 , and it has been increased remarkablyup to 52.8 fish m −2 , especially in some cases up to 75 fish m −2 (Liem 2009) .The productivity is, therefore, relatively high and kept improving. The averageproductivity of pond culture was 20.5 kg m −2 crop −1 in 2005 (Nhi 2005) and then36.9 kg m −2 crop −1 , the highest was greater than 500 kg m −2 in 2008 (Hien 2008) .High productivity of striped catfish culture in ponds has been due to the appropriateexploitation of the biological features of this air-breathing species in that they aregood survivors in condition of high stocking density. However, the vital factor forhigh productivity of striped catfish culture in pond is the improvement of culturetechniques, such as pellet feeding, deep ponds, and high water exchange regimes.7.7.3 Improvement of FeedsImprovement of feeds is one of the key factors for the success of striped catfishfarming. Feeds used in striped catfish farming have changed rapidly in the pastyears, especially after 2000 from low quality to nutritionally balanced feeds.During the early developing years of catfish culture, farm-made feeds (sinkingform) were mainly used. Phuong (1998) reported that in 1995, almost 100% catfishfarmers used low quality farm-made feeds prepared using by products from agricultureand fisheries. However, striped catfish has gradually been fed pelleted feeds(floating form). Liem et al. (2008) reported that the use of feed types for stripedcatfish varied by farm sites, 50–88% farms used pelleted feeds only and 13–40%farms a combination of pelleted and farm-made feeds. This indicates that stripedcatfish farming in the Mekong delta has gradually been moved from using farmmadeto pelleted feeds. However, because of the lower cost, the use of farm-madefeeds may continue. A study of Phuong (2007) indicated that striped catfish pondculture using farm-made feeds gave higher net profit compared to commercial pellet.The quality of recent farm-made feeds has improved significantly in whichdried low value fishes and soybean meal are used to improve its protein content.Nhi (2005) reported that the protein content in farm-made feed for pond culture