Use of Rotifer in Larviculture in Bangladesh

Rotifer any of the members of Rotifera, a minor phylum of animal kingdom composed of microscopic multicellar organisms recognizable by an anterior ciliary organ, known as corona. These minute organisms, also known as wheel animalcule, are principally inhabitants of freshwater bodies, though occasionally reported from salt water, and moist terrestrial habitats. These interesting animals constitute most important food item for the fishes. Zooplankton plays an vital role in the food chain of fish as animal food, which supply amino acids, fatty acids, vitamins, minerals, etc. (Watanabe et al., 1983). In spite of different efforts to replace live food by inert feeds, the rearing of fry and juvenile of fishes (specially zooplankton feeder) in nursery ponds mostly depend on the greater abundance of zooplankton (Habib et al., 1988).

Species Found in Bangladesh:Two of the most common zooplankton found in Bangladesh are Rotifer and Copepods. Many species of rotifers have been identified from different types of freshwater bodies in Bangladesh. Brachionid rotifers seem to be predominant and the common species recorded are Brachionus diversicornis, B. falcatus, B. quadridentatus, B. calyciflorus, B. havanensis and B. forficula. The other common genera in Bangladesh are Keratella, Monostyla, Lecane, Lepadella, Filinia, Trichocerca, Polyarthra, etc.

Uses of Rotifer in Larviculture:The successful use of rotifer in commercial hatchery operations of red sea beam (Pargus major) encouraged investigations in the development of mass culture techniques of rotifer. Twenty years ago, rotifer was first used in larviculture feeding. Fingerling production is one of the many challenges faced by those interested in promoting industrial production of emerging marine and fresh water species. In spite of huge efforts to use artificial feeds, the of fish larvae during the primary nursing phase still depends heavily on natural food. Live feeds include Rotifers, Artemia and other tiny organisms are often the enhancing larval production. These live foods are used in larviculture of carps, catfish and shrimp. Though there is not enough study on rotifer culture in Bangladesh.The benefits they are getting is discussed below.

Uses in Catfish:Larval nutrition and live feed culture like Artemia and rotifers is one of the most important and obligatory matter for successful fish culture. Feeding with live prey for fish larvae are most essential because during first few days of their life they have no complete develop digestive tract, especially their digestive enzymes. Moreover, live increases feeding by predatory larvae,

resulting reduce cannibalism of some species like Clarius gariepinus the enhancing larval production. Clarius gariepinus is generally considered as predator or omnivorous and also commercially important fish for aquaculture because they are able to tolerate to extreme environment conditions and worldwide demand.Awaiss and Kestemont studied the suitability of the freshwater rotifer Brachionus calyciflorus as starting food for the larviculture of African catfish.

Uses in Shrimp Culture:Now-a-days rotifers are used as replacement of Artemia in shrimp culture. In some coastal shrimp hatcheries of Bangladesh rotifers are used as successful larvae feed. Many marine fish hatcheries incorporate rotifers in their larval diets because rotifers are smaller than Artemia. With shrimp, Artemia is usually introduced in the Mysis stage, but most species can survive on rotifers from earlier stages. The success of extensive penaeid larvae rearing systems using rotifers in areas where Artemia and enrichment diets are prohibitively expensive or unavailable indicates that they are an alternative worth considering.

Rotifer

Conclusion:These are the reasons why the usage of rotifer is increasing day by day. In present state rotifer is only used in larviculture of shrimp. But hatchery owners should look for live food for larviculture instead of artificial food and rotifer is best suited live feed for larviculture. Though it lacks fatty acid components. We can enrich it by DHA and EPA.

References

1.http://www.shrimpnews.com2.http://www.banglapedia.org 3.www.banglajol.info4.Brendan Delbos, Research Specialist, Virginia Seafood Agricultural Research and Extension Center Michael H. Schwarz, Extension Aquaculture Specialist, Virginia Seafood Agricultural Research and Extension Center