الفهرس 
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Abstract
This study was carried out on Nile tilapia at Fish management and Behaviour ResearchUnit, Department of Veterinary Public Health, Faculty of Veterinary Medicine, Zagazig University. Three experiments were designed to investigate the effect of stocking density, water temperature of aquaria and feeding regime on the behaviour and performance of Nile Tilapia. During the period from November (2018) till the end of December (2019).
I- The effect of stocking density on behaviour, performance of Nile Tilapia and water quality.
In this experiment, 240 with 30 gram weight, apparently healthy Nile Tilapia fingerlings weredivided into four duplicated aquaria under four different rearing stocking density (15, 25, 35, and 45) fish were weighted individually every 14 days till the end of experiment to determine the growth rate parameters and study the effect of different stocking density on behaviour, performance of Nile Tilapiaand water quality.
1- There was a very high significant effect of stocking density on mean frequency andduration (sec) of feeding behaviour during weeks of experiment in groups (3 - 4)in compare with group (1) control.
2- There was a very high significant effect of stocking density on mean frequency and duration (sec) of foraging behaviour during weeks of experiment in groups (3 - 4) in compare with group (1) control.
3- Frequency andduration ofsurfacing behaviour weresignificantly higher at high stocking densities specially group (4) in compare with group (1) control.
4-Frequency and duration of surface swimming behaviourweresignificantly affected by stocking density, since it was the greatest in groupswith high stocking densitiesthan othergroups.