Color intensity and growth performance of common clownfish (Amphiprion ocellaris) enhanced by dietary Spirulina (Arthrospira platensis)

In this study, the effect of dietary Spirulina (Arthrospira platensis) on color intensity, growth performance, total ammonia–nitrogen excretion (TAN), and profitability of common clownfish (Amphiprion ocellaris) was investigated. Three isoproteic (46%) and isolipidic (13%) diets were formulated as one control (C) and two different levels (15 and 30%) of Spirulina (SP15 and SP30) substituted for fish meal and cornmeal. Ten clownfish (initial body weight of 0.55 ± 0.04 g) per aquarium were distributed to nine glass aquariums (60 L) with three replicates. Fish were hand-fed a day to the satiation thrice. Clownfish were weighed in bulk, and the photographs were taken biweekly during the 12-week experiment. The determined regions of the images were standardized with a raster graphics editor and recorded the color parameters by considering both CMYK (cyan magenta yellow key) and RGB (red green blue) models. After the feeding trial, fish were starved for 3 days, and the total ammonia–nitrogen (TAN) was analyzed with the ammonia salicylate method on the next day for 12 h. At the end of the trial, the final mean weights (FMW) and specific growth rates (SGR) of SP15 (FMW: 1.95 ± 0.18 g, SGR: 1.75 ± 0.04%/day) and SP30 (FMW: 2.05 ± 0.14 g, SGR: 1.81 ± 0.05%/day) were significantly higher than the C (FMW: 1.68 ± 0.12 g, SGR: 1.58 ± 0.06%/day) group (P < 0.05). Both color models have proved the enhancement of the skin coloration (significant improvements were recorded in the colors, including red, green, magenta, and key, P < 0.05). Also, it was determined that the TAN was decreased with the increase of the Spirulina level (29.8, 22.9, and 17.6 mg-N/100 g fish/12 h for C, SP15, and SP30, respectively) in the diet (P < 0.05). However, a high level of Spirulina in the diet negatively affected profitability. Consequently, common clownfish’s growth, color, and TAN improved with the dietary Spirulina. Considering that Spirulina is an expensive raw material, adding it into the diet at medium levels (15%) is recommended.