- marine algae for feeding Geo-duck larvae at Vandon, quang ninh province. - One of them is Geo-duck (Tuhai). - Geo-duck is a bivalve species, commonly in Halong Bay. - As the result, Geo-duck clam resource is decreasing seriously. - Therefore, researches on biological characteristics of Geo-duck for sustainable development and conservation of this resource is demanded. - For people of North Vietnam, Geo-duck culture is almost a new job. - These conditions will facilitate Geo-duck cultivation which is in the process at Van Don district, Halong Bay, Quang Ninh province, Vietnam.. - 48 days age Geo-duck larvae. - Geo-duck cuture tubes. - • Screeming of marine microalgal species with defined classification, high nutrient value and suitable for Geo-duck larvae at different stages and good for biomass large scale production.. - • Providing marine microalgal as fresh quality source of food for the 5000 artificial breed Geo-duck larvae.. - Geo-duck larvae cuture tank. - Geo-duck harvest