The Effect of Dietary Supplementation with Haematococcus pluvialis for Enhanced Pigmentation in Amphiprion ocellaris

Among the minority seawater species in the ornamental fish market, clownfish (Amphiprion ocellaris) have a high market value due to their vibrant appearance. Astaxanthin, a promising coloring agent, is applied in diets as a food additive to enhance the physical appearance of clownfish. However, as the retail price of astaxanthin has been inflating, the industry is eager to find more affordable astaxanthin products. The present study evaluated the nutrients and pigmentation performance of the algae-extracted astaxanthin diets of clownfish, followed by a comparative feeding trial evaluating the graded levels of either Haematococcus pluvialis powder or extracted astaxanthin supplements in the experimental diets. The study included three stages: assessing the utilization of H. pluvialis powder as an astaxanthin source, investigating the optimal practical extraction method, and revisiting the effects of crude extracted astaxanthin on clownfish based on the identified preparation processes. In the first stage, H. pluvialis powder was applied as the feed additive for a feeding trial, resulting in a low-utilization rate of astaxanthin in clownfish. This indicated that a suitable extraction method was essential for clownfish. Two chemical-based methods for astaxanthin extraction were investigated to obtain the optimal extraction yields; results showed that the HCl–acetone method had an astaxanthin yield of 21.99 ± 0.52 mg/g cell, which was significantly higher than the yield from the acetic acid-DMSO method. Finally, the effects of HCl–acetone-extracted astaxanthin was compared with the effects of synthesized astaxanthin. The pigmentation performance study was performed using a digital image acquisition and processing technique. A significant increase in the red color signal was observed at week six after fed with 400 and 200 mg/kg of the extracted astaxanthin, compared to the control 0 mg/kg. In conclusion, H. pluvialis-extracted astaxanthin following the HCl–acetone method can significantly improve the pigmentation performance of A. ocellaris after 42 days of oral administration.