Photo credit: Jean-Marie Manirambona (Burundi)
Review: Abdel Rahman El Gamal (Founder of the website)
Intensive culture of grass carp (Ctenopharyngodon idella) in China is practiced in several types including cages in open waters as shown in the inserted picture (governmental facility). Grass carp could be the only species stocked or the major species supported by few other species.
Based on published information, grass carp may be cultured in cages located at a depth of 2-2.5 m which are stocked with grass carp in addition to bluntnose black bream as well as silver and bighead carp which are stocked at a very low rate mainly for cage cleaning. Traditionally, caged fish are fed with pelleted/commercial feed supplemented with aquatic weeds/terrestrial grasses.
Under such situation, harvesting takes place after about 8-10 months of culture whereas the yield is normally 30-50 kg/m³ whereas 60-70% of total yield is credited to grass carp. The use of commercial feed adds significantly to the production costs. Moreover, if the used feed is not environmentally friendly, the uneaten feed and the wastes discharged by the fish can cause significant environmental pollution.
In order to enhance the culture conditions of course, the use of low volume, high density cages (LVHD) has been recommended and tried at Heng Xian Reservoir in Guangxi Province. The outcomes indicated the feasibility of the intensive growing of grass carp using highly digestible feed with no supplementation with fresh grass.