Effect of Dietary Astaxanthin on Growth Performance, Feed Utilisation, Body Colouration and Survival in Nile Tilapia ( Oreochromis niloticus )

ABSTRACT Astaxanthin is a potent dietary carotenoid known to enhance growth and pigmentation in fish. This study evaluated the effects of graded dietary astaxanthin supplementation, extracted from Haematococcus pluvialis (0, 25, 50, 75 and 100 mg/kg) on growth performance, feed utilisation, body colouration and survival of Nile tilapia ( Oreochromis niloticus ). A total of 375 fish with initial weight (4.31 ± 0.37 g) were randomly distributed into fifteen 110 L tanks in triplicate groups and reared for 60 days. Feed intake and condition factor were not significantly affected among treatments ( p > 0.05). Fish fed the 75 mg/kg diet exhibited significantly higher length gain (5.15 ± 1.04 cm), weight gain (14.90 ± 0.34 g) and specific growth rate (2.51 ± 0.14%/day) compared with other groups ( p < 0.05). Feed utilisation was also improved, with the lowest feed conversion ratio (1.48 ± 0.04) and highest feed conversion efficiency (0.68 ± 0.02). Survival rate was highest at 75 mg/kg (97.44 ± 1.22%) with no significant difference ( p > 0.05) from 100 mg/kg. Muscle carotenoid (4.84 ± 0.14 µg/g) and astaxanthin (0.22 ± 0.01 µg/g) increased dose dependently, with the greatest pigmentation observed at 100 mg/kg. Although the highest dose improved colouration, growth was slightly reduced compared with the 75 mg/kg group. These results indicate that 75 mg/kg dietary astaxanthin optimally enhances growth, feed efficiency, pigmentation and survival in Nile tilapia, supporting its use as a functional feed additive in aquaculture. Trial Registration : Not applicable