الفهرس 
Why sea bream fry?
Nutritional value of rotifer for larviculture:-Only 14 pages are availabe for public view
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Abstract
Aquaculture is one of the fastest growing animal food industries in the world. According to the Food and Agriculture Organization, Egypt is the largest aquaculture producer in the world. More than one billion people worldwide depend on fish as an important source of animal protein, healthy fats and essential micronutrients. The sea bream (Sparus aurata) is one of the only species of sea fish that is currently widely cultivated throughout the Mediterranean coast. Zooplankton animals are an important living food for fish of economic importance, where zooplankton forms a large part of the diet of marine fish larvae. Brachionus plicatilis and Cyclops vernalis are considered to be animal plankton that can meet the dietary requirements of fish larvae. The current study aims at the possibility of using different degrees of salinity and temperature to evaluate the culture of Brachionus plicatilis and Cyclops vernalis on the water wells and their effect on the productivity of the sea bass (Sparus aurata) fish fry. The results of the study can be summarized as follows: To study the effect of environmental factors such as temperature (20, 25, 30 °C) and salinity (20, 25, 30 ppm) on the density of zooplankton animals the present results showed that these factors significantly affect the total number of Brachionus plicatilis as well as Cyclops vernalis. Results revealed that the highest density of rotifers was at a temperature of 25°C and salinity of 25 ppt, but the highest density of copepods was at a temperature of 25°C and salinity of 30 ppt. The chemical analysis of copepods and rotifers results showed that the crude protein content of rotifers was 0.119% ±0.012 and copepod was 0.162 ±0.003. The present results were significantly (P≤0.05) different among the experimental groups. However, carbohydrate content of rotifers and copepods was significantly different, while the percentage of lipids higher in copepods (0.312% ±0.025) than rotifers (0.083% ±0.025) compared to control group (T1). To study the effect of feeding gilthead sea bream fish on a natural diet with different percentages of rotifers (T1), copepods (T2), and mixture of rotifers and copepods (T3) with a commercial diet (20%) added to all groups, results showed that there was a statistically insignificant increase in the rate of growth of gilthead seabreams between the tested groups. Also, the data showed that the survival rate of sea bream fed on different feeding regime was 72.5%, 68.33% and 60% for T2, T3 and T1, respectively. The present results showed that, there is insignificantly increase in the weight gain and specific growth rate when the sea bream (Sparus aurata) fed on copepods (T2) compared to group T3 and control groupT1. Also the data illustrated showed that there is an increase in the feed intake of the see bream in groups (T2 and T3) comparing with the group (T1). In addition, there is increase in the specific growth rate, growth rate and food conversation ration of the sea bream with the group (T2) comparing with the groups T3 and control group (T1). Chemical analysis of sea bream fry fed on different feeding groups after 30 days of feeding, the present results showed higher content in protein, carbohydrate and lipid in T2 compared with T3 and control group. The values of crude protein content of control group T1 was 0.160% ± 0.004 T2 group was 0.177% ± 0.021, and T3 was 0.162% ± 0.009. In addition, the values of carbohydrate for control group T1 was (0.031 ± 0.002), T2 (0.042 ± 0.002) and T3 (0.038 ± 0.004). However, the content of lipids for the tested groups was as follows T2>T3>T1 where the values were 0.305 ± 0.003, 0.197 ± 0.024 and 0.127 ± 0.016, respectively. The study of the histological investigation of the alimentary canal of sea bream (Sparus aurata) fed on different feeding regime showed remarkable variations between all the treatments of the diet groups. The heights numbers of goblet cells were observed when fish fed on the diet T2 while the diet T3 less than T2 in number of goblet cells, compared to control group (T1). The highest value for the muscularis was recorded in the intestine of fish fed on diet T2 and T3 while the control groups gained the lowest value of muscularis.