Evaluation of an aeration system for fish cultured in closed systems

الملخص EN

This study was Carried out at Central Laboratory for Aquaculture Research in (2017), to determine the best levels of oxygen supply on growth performance and oxidation status of Nile tilapia (Oreochromis nilollcus), Grey mullet (Mugil cephalus) and Common carp (Cyprinus carpio) fingerlings stocked at (85% , 10% and 5% ), respectively, total of fingerlings with initial weight of weighting (10±0.30) g/fish were reared in tanks i.

e.

, supplied with normal water, air pumping and filtration system applied throughout the experimental period, with 3 replicates to evaluate the effect of perforated pipe location i.

e.

, 0 and 100 cm from the bottom of tanks, distance between holes such as: 10cm, air pressure levels i.

e.

, 0.2 and 0.4 bar on water quality, growth rate of fish and net profit.

The obtained results revealed that the perforated pipe located at 100 cm with distance between holes such as: 10 cm and air pressure (P) of 0.4 bar gave the highest average of water quality like pH (7.72±.30 and 8.18±2.48 mg/l), dissolved oxygen (7.42±.29 and 8.38±2.54 mg/l), water temp (27C ±.81), ammonia (0.29±.01 and 0.28±.08 mg/l), total hardness (171.4±6.85 and 170.9±51.97), total alkalinity (165.3 ± 6.61 and 180.7±54.95 mg/l), nitrate (0.01±.0004 and 0.01±.003), nitrite (0.11±.004 and 0.12±.03) for air pressure levels (0.2 and 0.4) bar respectively.

Compared with control result which were 6.7±.30, 4.45±2.54, 0.32±01, 25.0±2.16, 340±2.71, 370±12.7, 0.12±008 and 0.40±0.001 for pH, dissolved oxygen, water temp, ammonia, total hardness, total alkalinity, nitrate and nitrite.

The highest average of growth rate values; final body weight (74.9±22.77, 77.4±1.16 and71.9±3.59 g), final body length (19.2±5.83, 18.2±.27 and 16.4±0.32 cm), final body weight gain (5±0.20, 4.4±0.06and 4.6±0.09g), final condition factor (1.36±0.05, 1.38±0.23and 2.61±0.26g/cm³) and final feed conversion ratio (1.56±0.47, 1.62±0.02 and1.68 ± 0.03 g/fish), Final SGR were (1.93±0.58, 1.68±0.02 and 2.0 ±0.04% ) and final survival rate (% ) were (91.8±2.9, 88.9±2.6 and 90.2±1.2) for Nile tilapia (Oreochromis nilollcus), Grey mullet (Mugil cephalus) and Common carp (Cyprinus carpio) and distances between holes of 10 cm and pressure levels of 0.4 bar Respectively.

Finally, it could be concluded that, under the similar conditions: The Air pressure (P) level of 0.4 bar, perforated pipe location of 100 cm and distance between holes 10 cm were the best parameters where it gave Significantly high water quality, growth performance (P<0.0001) and survival of fish (P<0.0001) was observed in aerated tanks as compared with the non-aerated tanks.