Astaxanthin extraction from golden apple snail (Pomacea canaliculata) eggs to enhance colours in fancy carp (Cyprinus carpio)

High-value ornamental fish farming is one of the most valuable industries in the recent years, and the commercial value of ornamental fish, such as fancy carp (Cyprinus carpio) is primarily dependent on their body coloration. Therefore, a trial was conducted to investigate skin colour enhancement in fancy carp by feeding different levels (0, 25, 50, 100 and 200 mg/kg) of a dietary natural astaxanthin extracted from golden apple snail (Pomacea canaliculata) eggs, using a diet containing synthetic astaxanthin (50 mg/kg) and a control diet with no colouring added for comparison. The duration of the trial was four weeks with experimental diets containing carotenoid followed by the low carotenoid diet for other two weeks. The chromaticity of fish body skin of red and white position was assessed using the CIE L* a* b* system. Pigmentation response of skin redness (a*) of fancy carp fed with diets at 50, 100 and 200 mg/kg of natural astaxanthin supplement was higher than other treatments (P < 0.05). The lightness and yellowness (L* and b* values) indexes of carp fed with diet containing astaxanthin from golden apple snail eggs were similar compared to the other dietary treatments (P > 0.05). After two weeks of feeding diet without natural carotenoid supplement demonstrated that the group fed 50 mg/kg of natural astaxanthin still retained their redness (a*) and also had an overall tendency to improve skin colouring (L* and b*). Finally, dietary concentrations 50 mg/kg of astaxanthin extracted from golden apple snail eggs showed the highest efficiency for improving skin pigmentation in fancy carp.