**3. Results**

196 Aquaculture

hatching. All specimens that survived past Day 14 after hatching were sacrificed, for total

Eggs were stocked in 2 L PVC floating containers, similar containers were at the same time floating in a 300 L raceway tank. Three raceway tanks were used, each one of them had a different temperature (23, 28 and 30°C). Each raceway tank had three 2 L PVC floating container and each container was stocked with 100 snook eggs per litre. Aeration was removed before stocking. Water quality parameters were maintained within acceptable values. Twenty hours after fertilization, containers were removed from the raceways and percent hatch was determined (see the formula below). This experiment was replicated four

**Hatch rate= Total number hatched larvae / Total number of eggs stocked \*100** 

Nine tanks were stocked with three different egg densities (three replicates per density). The densities used were: high density (375 eggs**/**L), medium density (200 eggs**/**L) and low density (200 eggs**/**L). All tanks were fed S type rotifers three times a day at a concentration of 30 rot/ml. The tanks were harvested fourteen days after hatch (DAH) and larvae were counted and measured (total length and myomere height). This experiment was run in both

Common snook eggs were stocked at a density of 200 eggs/L and exposed to three different flow rates (no flow, slow flow (10 ml/min) and high flow (30 ml/min)). Each flow treatment had 3 replicates per day. All tanks were fed three times a day with SS type rotifer at a concentration of 30 rotifers/ml. System A tanks (27 tanks) were stocked, nine per flow

**2.3.4 Effect of background phytoplankton in the water (Green water technique) on** 

Snook were stocked at 200 eggs/L in ten system A tanks and the flow rate was set at 15 ml/min. Five tanks were stocked with *Nannochloropsis oculata* at 1000/ml (green water) and five tanks without (clear water). All tanks were fed SS type rotifers three times a day with a concentration of 30 rot/ml. The experiment was terminated at 14 DAH and all larvae were counted to establish larval survival and measured (total length and myomere height) for

The effect of rotifer density on larval survival was evaluated in 15 System A and System B tanks. Three SS type rotifers densities were used with: 5 rotifers/ml, 15 rotifers/ml and 30 rotifers/ml. All the tanks were stocked at the same time with 200 eggs/L. Residual rotifer

treatment. Larvae were harvested on 3, 6 and 10 DAH to determine survival.

**2.3.2 Effect of egg stocking density on larval survival and growth** 

length and myomere height measurements.

times to obtain reliable results.

systems A and B.

**larval survival and growth** 

growth.

**2.3.1 Influence of temperature on hatch rate** 

**2.3.3 Influence of flow rate on larval survival** 

**2.3.5 Influence of rotifer density on larval survival** 
