A 6d trial with Videomex-V image motion monitor system was conducted to investigate the activity levels and rhythms in hybrid tilapia (Oreochromis niloticus female x O. aureus male) on different feeding times. The trial was carried out in a self-circulation system consisting of 36 organic glass tanks (28cm x 24cm x 20cm, water 10-12cm deep). The monitor light period was from 8:00-19:00 and the dark period from 20:00-7:00,and two hours were spent to adjust image motion monitor system from 7:00 to 8:00 and 19:00 to 20:00. During the experiment, dissolved oxygen was maintained above 5.53mg/L, ammonia below 0.1025mg/L and temperature 25 degrees C.The fish were deprived of diet for one day at the beginning of the experiment, and then individual fish was randomly selected, batch-weighed and allocated into each tank. The 36 tanks were divided into 4 groups and each group contained 9 tanks selected randomly. The fish were fed twice a day and the feeding time was 8:00 + 14:00,14:00 + 20:00, 20:00 + 2:00 and 2:00 + 8:00 individually (expressed by S1, S2, S3 and S4 individually) and uneaten feed was collected 60 min after feeding.The results showed that the diet weights per body weight were significantly lower in groups S1 and S2 than in groups S3 and S4, and S1 and S2 were similar, S3 and S4 being, too; Activity rhythms, not swimming distance and time per day, were affected significantly by feeding time, and S1 had more similar activity rhythms to S2, and S3 had more similar activity rhythms to S4.
Yang Yan-Ou (firstname.lastname@example.org) ; Xie Shou-Qi; Yao Feng; Yang Yun-Xia; Zhu Xiao-Ming; Lei Wu.The effects of feeding time on activity levels and rhythms of hybrid tilapia (Oreochromis niloticus female x O-aureus male),Acta Hydrobiologica Sinica,2008,32(1):38-41