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\hypersetup{pdftitle={Effect of Population Density on Growth Performance, Survival and Feed Utilisation of Gilthead Sea Bream, \textit{Sparus aurata}, Fry Nursing in Net Hapas and Fiberglass Tanks},pdfauthor={Deyab El-Saidy, Mohamed Essa, Mohamed Abdel-Rahim, Habiba Mahmoud, Ashraf Goda},pdfsubject={Tropentag 2016: Abstract},pdfkeywords={Feed utilisation, fish holding facility, Gilthead sea bream, growth performance, nursery performance, stocking density, survival},pdfpagemode=None,colorlinks=true}
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\parbox[b]{13.4cm}{\centering \large{\textbf{Tropentag, September 18-21, 2016, Vienna, Austria}}\\[1ex] \Large{``Solidarity in a competing world ---\\fair use of resources''\\[2ex]}}
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\Large{\textbf{Effect of Population Density on Growth Performance, Survival and Feed Utilisation of Gilthead Sea Bream, \textit{Sparus aurata}, Fry Nursing in Net Hapas and Fiberglass Tanks\footnote{\textbf{Contact Address:} Mohamed Essa, National Institute of Oceanography and Fisheries, Aquaculture Division,  Samy Raouf Str. No. 8 from Iskander Ibrahim Miami,  Alexandria, Egypt, \mbox{e-mail}: \email{messa51@yahoo.com}}\\[0.8ex]}}
\normalsize{\textsc{Deyab El-Saidy$^{1}$, Mohamed Essa$^{2}$, Mohamed Abdel-Rahim$^{2}$, Habiba Mahmoud$^{2}$, Ashraf Goda$^{2}$}}
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\begin{itemize*}
\item[]{\small{\textit{$^{1}$Monofya University, Animal, Poultry and Fish Department, Egypt}}}
\item[]{\small{\textit{$^{2}$National Institute of Oceanography and Fisheries, Aquaculture Division, Egypt}}}
\end{itemize*}
\index[author]{El-Saidy, Deyab}
\index[author]{Essa, Mohamed}
\index[author]{Abdel-Rahim, Mohamed}
\index[author]{Mahmoud, Habiba}
\index[author]{Goda, Ashraf}
\begin{center}
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\textbf{Abstract}
\begin{abstract}
\normalsize{
Rearing fish fry at inappropriate stocking densities may impair growth and reduce immune competence. Therefore, the effect of stocking density on growth performance, survival and feed utilisation efficiency of gilthead sea bream, \textit{Sparus auratus}, fry were evaluated under two nursing conditions, in net hapas or fiberglass tanks using underground saline water (31$\pm$1 ppt). The tested stocking densities were 25, 50, and 75\,{fish}\,{m}\textsuperscript{3} and fish holding facilities were suspended net"=enclosure hapas and circular fiber"=glass tanks. A total of 900 gilthead sea bream fry, with an average initial body weight of 0.15 g/fry were stocked on nine tanks each of 2 m\textsuperscript{3} water and 9 hapas (2\,m$\times$1\,m$\times$1m=2\,m$^{3}$ water) at stocking density of 50, 100 and \unitfrac[150]{fish}{tank} or hapa with three replicates for each treatment. Fish were fed on artificial feed containing \mbox{45\,\%} crude protein three times daily . The feeding rates were adjusted according to bi"=weekly periodical fish samples. 



After 75 days, the results revealed that the survival percent was higher in hapas (\mbox{93.56\,\%}) than tanks (\mbox{68.33\,\%}). Also, the highest growth performance (determined in terms of weight gain) was recorded in hapas (1.97\,g) while tanks recorded the smallest growth rate (1.14\,g). Values of feed utilisation efficiency were significantly  better under hapas conditions than tanks (FCR 2.25 VS 2.80). The same trend observed in the values of the protein and energy utilisation. But in terms of the interaction between population density and the method of farming in tanks or hapas results showed that nursing the fry of sea bream in hapas at a density of 25 and 50 fry per cubic meter have achieved best growth rate parameters , while fry growth did not exceed 1.59\,g in the case of tanks. The same trends are observed in both dietary protein and energy utilisation. The water quality parameters throughout the study period were found within the suitable ranges.



From the previous results, it could be concluded that nursing sea bream fry in net hapas at 25 or 50\,{fish}\,{m}\textsuperscript{-3} showed the best performance and most economically feasible treatments.
}

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\end{abstract}
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\noindent \textbf{Keywords:} Feed utilisation, fish holding facility, Gilthead sea bream, growth performance, nursery performance, stocking density, survival
\index[key]{Gilthead sea bream}
\index[key]{Feed!utilisation}
\index[key]{Fish holding facility}
\index[key]{Growth!performance}
\index[key]{Nursery performance}
\index[key]{Stocking density}
\end{document}
