Effect of feeding regime and fish size on weight gain, feed intake and gastric evacuation in juvenile snapper Pagrus auratus.
Summary
The cost of feeding fish grown for commercial purposes is expensive and can cost farmers as much as 60% of their operating budget. Prices for commercial feeds for marine fish can range from $1500 - $2000 per tonne and feeds for juvenile fish are usually more expensive. In order to be profitable farmers need to ensure their feeds are being used efficiently. One way they can ensure their feeds are used efficiently is to make sure that the fish they are growing are fed the correct amount of feed at the most suitable time or times of day. Doing this can dramatically improve feed conversion and growth rates on farms and improve the growth rates, health, vigour and survival of fingerlings in hatcheries.
This study was designed to determine the best daylight feeding regime for juvenile Australian snapper fed a commercial diet and weighing more than 5g but less than 60g. The day length was set to 18 hours using automated lighting and water temperature was set to approximately 24°C. Different feeding regimes were tested to see if they affected the weight gain and performance of fish. The regimes included feeding snapper 1, 2, 4, 6 or 8 feeds per day at various times.
The study indicated that for juvenile snapper weighing between 5 to 60 g, optimum to maximum weight gain and feed conversion was achieved by feeding snapper at least twice a day. This corresponded to feeding at 8.00am and 4.00pm or 12.00am and 8.00pm, respectively. Feeding more often than this did not significantly improve weight gain or performance in fish of this size. This information will help operators of snapper hatcheries / nurseries plan their feeding regimes and assist with benchmarking performance.