A study was performed to evaluate the efficacy of shrimp shell meal derived natural astaxanthin (SSM), supplemented with its commercial variant on gonadal maturation and vitellogenin gene (Vtg.) expression in reproductively active adults of the high-value ornamental cichlid discus (Symphysodon aequifasciatus) reared under captivity. Four isonitrogenous (50% crude protein), isolipidic (9% ether extract), and isocaloric (400 kcal digestible energy/100 g) experimental diets viz. control (commercial grade astaxanthin, without SSM), T1 (15% SSM + commercial astaxanthin), T2 (20% SSM + commercial astaxanthin), T3 (25% SSM + commercial astaxanthin) were prepared and fed to satiation level twice daily for the entire experimental period of 90 days. Results revealed significant (p < 0.05) linear, quadratic, and overall trends, wherein GSI increased with an increase in the proportion of SSM in the diet, with higher GSI recorded in T2 and T3 treatment groups (testis and ovary, respectively), which were significantly (p < 0.05) different from other groups. The overall linear and quadratic trends of HSI differed significantly (p < 0.05) with the variability in proportions of natural and commercial astaxanthin combinations and were found highest in the T2 treatment group. Cholesterol, FSH, LH, 11-KT, 17β- Estradiol, and 17α-20β DHP levels increased with an increasing proportion of natural astaxanthin and recorded the highest values in the treatment T2 with an overall significant linear and quadratic trend as compared to other treatments. Most of the oocytes of T2 and T3 groups were in the vitellogenic phase, i.e., primary, secondary, and tertiary yolk stages. More spermatids were visible in testicular tubules in T2, followed by T3 and T1. The abundance of Vtg. mRNA was significantly (p < 0.05) evident in T2, followed by T1, then in control. Further increase in SSM inclusion caused a downregulation in the expression of this gene in the T3 group. The dietary combination of SSM @200 g/kg diet with its synthetic/commercial variant exhibited optimum performance at combination levels of 77.5 and 22.5 mg/kg, respectively, evidenced in terms of changes in steroid hormone profiles, gonadal maturation and vitellogenin gene expression in comparison to the control, which contained the dietary synthetic/commercial variant of astaxanthin alone. These inferences are presumably a milestone in the captive broodstock development of this high-value ornamental cichlid, S. aequifasciatus, with an added advantage of cost-effectiveness. The study would help the utilisation of economically important bio-waste in combination with commercial variants for effective value addition in the ornamental fish feed industry.

进行了一项研究以评估虾壳粉衍生的天然虾青素 (SSM) 的功效，并辅以其商业变体对高价值观赏慈鲷 ( Symphysodon aequifasciatus ) 生殖活跃成虫的性腺成熟和卵黄素基因 (Vtg.) 表达的影响) 在圈养下饲养。四种等氮（50% 粗蛋白）、等脂（9% 醚提取物）和等热量（400 kcal 可消化能量/100 g）实验日粮，即。制备对照（商品级虾青素，不含 SSM）、T1（15% SSM + 商品虾青素）、T2（20% SSM + 商品虾青素）、T3（25% SSM + 商品虾青素），每天两次喂食至饱腹水平。整个实验期90天。结果显示显着（p < 0.05) 呈线性、二次和总体趋势，其中 GSI 随着日粮中 SSM 比例的增加而增加，在 T2 和 T3 治疗组（分别为睾丸和卵巢）中记录到更高的 GSI，显着（p < 0.05) 与其他组不同。随着天然和商品虾青素组合比例的变化，HSI 的整体线性和二次趋势显着不同（p < 0.05），并且在 T2 治疗组中发现最高。胆固醇、FSH、LH、11-KT、17β-雌二醇和 17α-20β DHP 水平随着天然虾青素比例的增加而增加，并在 T2 处理中记录了最高值，与其他处理相比，总体呈显着的线性和二次趋势. T2和T3组的大部分卵母细胞处于卵黄生成期，即初级、次级和第三级卵黄期。在 T2 的睾丸小管中可见更多的精子细胞，其次是 T3 和 T1。丰富的Vtg。mRNA 显着 ( p < 0.05) 在 T2 中明显，其次是 T1，然后在控制中。SSM 包含的进一步增加导致该基因在 T3 组中的表达下调。SSM @200 g/kg 饮食与其合成/商业变体的饮食组合分别在 77.5 和 22.5 mg/kg 的组合水平下表现出最佳性能，这在类固醇激素谱、性腺成熟和卵黄原蛋白基因表达的变化方面得到了证明与对照组相比，对照组仅含有虾青素的膳食合成/商业变体。这些推论可能是这种高价值观赏慈鲷S. aequifasciatus 圈养亲鱼发育的里程碑，具有成本效益的额外优势。该研究将有助于利用经济上重要的生物废物与商业变体相结合，在观赏鱼饲料行业实现有效增值。