豹纹鳃棘鲈(Plectropomus leopardus)早期形态与色素变化及添加剂对其体色的影响

为研究豹纹鳃棘鲈色素变化过程以及添加剂对其产生的影响,本研究在室内工厂化养殖条件下,对豹纹鳃棘鲈的早期色素积累、转变过程进行描述,并采用螺旋藻粉和虾青素两种添加剂对其仔、稚、幼鱼的生长及体色变化的影响进行观察。结果显示,从2 d仔鱼开始,眼点色素增多,并由透明转为黑色,摄食明显;3 d仔鱼其背部鳍褶上的树枝状黑色素扩大,脊椎下方出现1列黑色素细胞丛;22 d的鱼体脊椎上方出现1排黑色素斑点,下方黑色素斑点数量减少,此时口、各鳍基部及沿脊椎两侧黄色素增加;28 d的稚鱼体表黄色素与红色素进一步增多,各鳍沿鳍条均有红色素斑点分布,鱼体呈橘红色,颜色鲜艳;30–33 d的幼鱼体表两侧布满黑色与橘红色斑点,脊椎下方斑点消失,仅在尾椎下方存有1块黑色素斑点。增色剂实验结果显示,实验15 d时,螺旋藻粉组与虾青素组全长、体重差异不显著,但均显著高于对照组(P0.05),各实验组内梯度之间差异不显著(P0.05)。30 d时,3%和6%螺旋藻粉组较对照组的体重值高,但差异不显著(P0.05),9%螺旋藻粉组显著低于对照组(P0.05);虾青素组均高于对照组,除与0.6%组差异不显著(P0.05)外,其他组均差异显著(P0.05)。0.1%实验组体重高于对照组和螺旋藻粉组,并高于组内其他梯度组。经过15 d添加虾青素的幼鱼体色红色素有明显增加,与对照组差异显著;30 d时,螺旋藻组没有达到增色效果。结果表明,螺旋藻粉对幼鱼生长初期有促进作用,随着添加浓度与养殖时间的增加其效果不明显,出现负效应;添加浓度为0.1%的虾青素可使全长、体重增长率最高并具有明显增色效果。

Morphology of the Early Age and the Pigment Occurrence and the Effects of Different Feed Additives on the Body Color of Plectropomus leopardus

The current study investigated the early pigment accumulation and transformation process of Plectropomus leopardus and evaluated the effects of two feeding additives on growth and body color traits. The results indicated that larval eyespot pigment granules gradually increased at day 2, the white eyes became black, and the feeding behaviors appeared. The arborization melanin area extended on the back fin at day 3, and a melanocytes plexus appeared at the bottom of the spine. At 22 d, the row intermittent melanin spots appeared above the fish spine and the number of melanin spots reduced. The mouth, the base of the fins and both sides of the spine became pale yellow. At 28 d, the accumulation of yellow and red pigment of the juvenile was further increased, which were surrounded by lots of red pigment spots. The fish had vivid orange color. At 30-33 d, the surface of both sides was covered with dense black and orange spots. The chunks of the spots were disappeared under the spine except a large melanin spot at the bottom of the caudal. The spirulina powder and astaxanthin had similar and significant effects on the full length and body weight of Plectropomus leopardus （P〈0.05） at day 15. At day 30, 9%but not 3%and 6%of spirulina powder had significant effects on the body weight （P〈0.05）. Compared to the control, all astaxanthin treatments （except the 0.6% group） significantly increased the body weight with the best treatment of 0.1%experimental group. At day 15, astaxanthin markedly improved the body color. At day 30, the spirulina powder did not improve the body color. These results demonstrated that the spirulina powder may contribute to the early development of the juveniles but negatively affected the growth with the increase of feeding concentrations and the breeding time; however, and that 0.1%astaxanthin treatment was effectively enhance fish growth and body color development.