World Aquacluture Magazine - September 2020

WWW.WA S.ORG • WORLD AQUACULTURE • SEP TEMBER 2020 51 FIGURE 5. Hatching tanks (500 L). FIGURE 4. Fertilized eggs of snubnose pompano collected from spawning tanks. ( C O N T I N U E D O N P A G E 5 2 ) fertilized egg quality was better than that of smaller broodstock. Also, the quality of fertilized eggs and the spawning period was not different for broodstock fed with a commercial feed or trash fish. The number of spawned eggs was 200 to 250/g (Fig. 4). Collection and Hatching of Fertilized Eggs Fertilized egg collection began in the early morning, not later than 0800 h, to avoid early hatching at high temperature. First, we observed the quality and number of fertilized eggs. Second, we used a 120-μmmesh net to collect fertilized eggs from the surface. Third, fertilized eggs were moved to the hatchery and seawater was used to gently clean them. Eggs were allowed to float to the tank surface for around 5 min before collection and transfer to hatching tanks (Fig. 5). FIGURE 3. Snubnose pompano broodstock. FIGURE 6. Spine deformity in a snubnose pompano fry (4 dph). Larviculture In the larviculture stage, we confronted many difficulties, such as high water temperature and extreme salinity. On the coast of the Red Sea near Jeddah, Saudi Arabia, the average seawater temperature is 32 to 40 C, and the salinity is 42 to 45 ppt during the peak production period. High salinity causes deformity of fry 4 days post-hatch (dph) (Fig. 6). Against this background, we designed a research project to address the issue of high salinity. After hatching, we cultured pompano fry at different salinities (42, 39, 33, and 25 ppt), using freshwater to dilute seawater, and observed and recorded survival rates to identify the most favorable culture environment. We cultured 1,000 fry per salinity in a water