Diet feeding, oxygen consumption rhythm and gastrointestinal evacuation time of Trachinotus ovatus

In order to determine a scientific feeding strategy for Trachinotus ovatus, we investigated the day and night diet feeding, oxygen consumption rhythm and gastrointestinal evacuation time of the fish in laboratory. The diet feeding rhythm was invstigated by a continuous feeding with fixed interval (feeding once every two hours day and night for three continuous days). The oxygen consumption rhythm was measured by flow-water breathing method (measuring once every two hours day and night for 24 h). The gastrointestinal evacuation time was measured by a full feeding method (sampling once every two hours day and night for a day). Results show that T. ovatus had a daytime feeding pattern with two extremely obvious feeding peaks (10:00 and 14:00−16:00, P<0.05), and the peak periods of oxygen consumption appeared at 08:00 and 16:00, respectively (P<0.05). The stomach digesta ratio of T. ovatus decreased sharply after feeding (P<0.05), nearly 50% at 7^th hour, and reached to zero after 19 h. However, the bowel digesta ratio of T. ovatus increased sharply after 1−3 hours of feeding, and reached the maximum at 11^th hour and the minimum at 21^st hour. Thus, it is suggested that the optimal feeding periods of T. ovatus are 09:00−10:00 and 14:00−16:00 with strong light, oxygen consumption and peak feeding. The feeding frequency is 2−3 times per day and the feeding interval is 7−9 h.