EFFECTS OF FEED ON THE SURVIVAL RATE, GROWTH RATE AND METAMORPHOSIS TIME OF THE WHITE LEG SHRIMP LARVAE (Litopenaeus vannamei Boone, 1931) AT ZOEA STAGE

The larvae of white leg shrimp ( Litopenaeus vannamei Boone, 1931) at phase nauplii 6 fed with a stocking density of 150 pcs per litre and 3 formula including formula 1 with dry microalgae Spirulina + artemia as main ingredients, formula 2 with microalgae Thalasiosira weissflogii + artemia as main ingredients and formula 3 with microalgae Thalasiosira pseudonana + artemia as main ingredients. Experiments were carried out in 18 tanks fifty-litre composite at Quang Binh branch of C.P Vietnam Corporation. The study results show that, with formula 3, white leg shrimps larvae at zoea stage have the highest growth and survival rates (86.57 %), followed by formula 2 (76.03 %) and finally formula 1 (67.90 %). White leg shrimps larvae at zoea stage in formula 3 have the shortest metamorphosis time (78.61 hours), followed by formula 2 (83.25 hours) and the longest in formula 1 (94.10 hours).