EFS40和EFS60对青鳉胚胎毒性的研究

以青鳉受精卵为试验材料,研究了2种抗冻液EFS40和EFS60对5个不同发育期的胚胎的毒性作用.试验结果表明,青鳉的囊胚期胚胎对EFS40和EFS60的毒性耐受力最差,在EFS40 和EFS60中处理2 min后的成活率分别为41.7%和35.6%,孵化率分别为38.2% 和31.9%,与对照组成活率(96.7%)与孵化率(93.3%)差异极显著(P<0.01);6肌节、16肌节和24肌节胚胎对EFS40 和EFS60的耐受力依次增强;发眼期胚胎的耐受力最强,其胚胎在EFS40中处理30 min后的成活率仍为93.3%,孵化率为77.3%,其余各时期胚胎成活率均显著地降低(P<0.01),发眼期胚胎在EFS60中处理20 min的成活率为75.9%,孵化率70.6%,其余各时期胚胎的成活率都显著地降低(P<0.01).各时期的青鳉胚胎在EFS40和EFS60中都随着毒性处理时间延长其成活率和孵化率逐步降低.EFS60对青鳉胚胎的毒性大于EFS40.     

翘嘴鳜皮肤、鳞片、鳍色素细胞显微观察

采用冰冻切片和常规苏木精—伊红染色切片,在光学显微镜下观察了体质量500 g 1龄翘嘴鳜皮肤、鳞片和鳍色素细胞的组成、分布及形态特征。皮肤纵切显微观察显示,眼后头部、体侧黑斑、体侧下部皮肤主要含黑色素细胞,喉部及腹部皮肤主要含虹彩细胞。皮肤横切显微观察显示,在皮肤表面,黑色素细胞聚集呈团状或块状,黄色素细胞呈颗粒状,虹彩细胞呈长梭形。苏木精—伊红染色下,皮肤黑色素细胞呈棕黑色,虹彩细胞呈浅灰色。皮肤色素层主要分布在表皮层与真皮疏松层之间、真皮致密层与肌肉相连处,少量分布在真皮疏松层纤维组织上。鳞片显微观察显示,眼后头部、体侧黑斑、体侧下部鳞片主要含黑色素细胞、黄色素细胞;喉部及腹部为透明状,不含或含少量黑色素细胞及黄色素细胞。鳞片黑色素细胞胞体大,胞体周边分枝多且细,黄色素细胞呈颗粒状。鳍显微观察显示,鳍主要含黑色素细胞及黄色素细胞,不同部位各色素细胞占比、大小及着色存在较大的区别。翘嘴鳜在长期的进化过程中,通过黑色素细胞、黄色素细胞、虹彩细胞不同的调配比及着色深浅,从而形成了具有独特特征的条纹及图案,利于隐藏及捕食,同时具有一定的观赏性。     

黄河鲤酪氨酸酶基因的克隆、表达模式及定位分析

为探究Tyrosinase(Tyr)基因在黄河鲤体色形成中的作用,利用生物显微镜对黄河鲤黑色鳞片、银色鳞片、鳍条色素细胞的组成进行观察,并利用RACE克隆黄河鲤Tyr基因全长cDNA序列,荧光定量PCR分析其在不同组织中的表达情况,Western blot印迹和免疫组织化学方法检测其蛋白的表达定位。结果显示,黄河鲤具有黑色素细胞、黄色素细胞和虹彩细胞3种色素细胞,3种色素细胞的数量、种类和分布在不同组织中存在较大差异。黄河鲤Tyr基因cDNA全长1717 bp(GenBank ID:No.KY305667),其中ORF长1605 bp,编码535个氨基酸,5′-UTR区41 bp,3′-UTR区71 bp。蛋白同源分析发现,黄河鲤Tyr与鲤科鱼类相似性最高,与哺乳类及鸟类等脊椎动物相似性最低。系统进化分析显示,黄河鲤Tyr与鲤、瓯江彩鲤、锦鲤和斑马鱼等鲤科鱼类的亲缘关系最近。实时定量PCR分析表明,Tyr基因在黄河鲤不同组织中均有表达,肌肉中的表达量最高,其次是黑色皮肤,另外在黄色皮肤、臀鳍和尾鳍等黑色素细胞存在的组织中也有较高表达。Western blot印迹结果显示,Tyr基因在黑色皮肤中表达最高,其次是臀鳍和尾鳍,银色皮肤中没有表达。免疫组织化学结果显示,Tyr基因在黑色皮肤的黑色素细胞和黏液细胞中有表达。研究表明,Tyr基因表达水平与黑色素细胞数量和分布具有一定相关性,参与黄河鲤体色的形成。     

橘色双冠丽鱼黑色素细胞和黄色素细胞的分离、培养与鉴定

为探讨橘色双冠丽鱼(Amphilophus citrinellus)黑色素细胞和黄色素细胞的分离、培养与鉴定方法,观察鱼类色素细胞生长特征,本研究以橘色双冠丽鱼的尾鳍、鳞片、皮肤组织为材料,在25℃~28℃条件下,分别在胰蛋白酶溶液和胶原酶溶液中消化6 h和12 h,可有效分离出色素细胞团,细胞悬液经气孔尼龙网过滤后,于35%-45%-55% Percoll试剂中梯度分离和收集黄色素细胞和黑色素细胞。采用K-SFM培养基进行细胞原代培养和细胞纯化,抑制成纤维细胞和角朊细胞的生长,用十四烷酰佛波醇乙酸酯(TPA)、双抗、bFGF的DMEM培养基进行色素细胞传代培养;运用巴染色和透射电镜观察细胞形态,并用分子标记技术进行细胞鉴定。结果显示,细胞分离时,黑色素细胞位于Percoll试剂45%和35%浓度层之间,黄色素细胞位于Percoll试剂35%浓度层上,2种色素细胞均凝聚成絮状。透射电子显微镜观察发现,黑色素细胞内部含大量黑色素小体,而黄色素细胞内部含喋呤体和类胡萝卜素囊泡;黑色素细胞左旋多巴(L-DOPA)染色呈阳性;取第10代色素细胞进行体色相关基因黑皮素1受体(melanocortin receptor 1, MC1R)、酪氨酸酶(tyrosinase, TYR)和牛内皮素受体B(endothelin receptor B, EDNRB) PCR检测,显示基因扩增条带特异性强,表明获得的2种色素细胞具有良好的生物学活性。本研究建立了橘色双冠丽鱼黄色素细胞和黑色素细胞的分离培养与鉴定方法,为进一步开展鱼类体色细胞分化和体色形成的分子机理研究提供了细胞模型。     

半滑舌鳎(Cynoglossus semilaevis)体表色素细胞观察及POMC表达特性分析

为认识养殖半滑舌鳎无眼侧黑化的细胞学特性,利用显微观察方法研究了其皮肤黑色素细胞、黄色素细胞和虹彩细胞的形态特征,比较了3种色素细胞在有眼侧皮肤、无眼侧正常和黑化皮肤中的数量分布特征。为进一步揭示无眼侧黑化的分子机制,克隆了半滑舌鳎POMC基因的cDNA序列。结果显示,黑色素细胞较大,含黑色和棕色的色素颗粒,有树突状分枝不明显和延伸成放射状两种形态;黄色素细胞较小,含黄色素颗粒;虹彩细胞最小,含鸟粪素颗粒。半滑舌鳎POMC基因的cDNA序列长910 bp,包括一个114 bp的5?非翻译区和一个154 bp的3?非翻译区,开放阅读框长度为642 bp,共编码213个氨基酸,包含ACTH、α-MSH、β-MSH、γ-LPH、β-内啡肽5个多肽序列,但缺失γ-MSH和大部分连接区。半滑舌鳎POMC基因的氨基酸序列与其他鱼类的同源性为30%?64%。定量PCR分析显示,POMC mRNA主要在垂体中表达,其次是脑、性腺和无眼侧黑化皮肤。正常与黑化皮肤中的差异表达结果显示,无眼侧黑化皮肤中POMC mRNA表达量最高,并与有眼侧皮肤和无眼侧正常皮肤中的POMC mRNA表达量差异显著,揭示了POMC的表达与无眼侧黑化性状密切相关。     

半滑舌鳎(Cynoglossus semilaevis)体表色素细胞观察及POMC表达特性分析

为认识养殖半滑舌鳎无眼侧黑化的细胞学特性,利用显微观察方法研究了其皮肤黑色素细胞、黄色素细胞和虹彩细胞的形态特征,比较了3种色素细胞在有眼侧皮肤、无眼侧正常和黑化皮肤中的数量分布特征.为进一步揭示无眼侧黑化的分子机制,克隆了半滑舌鳎POMC基因的cDNA序列.结果显示,黑色素细胞较大,含黑色和棕色的色素颗粒,有树突状分枝不明显和延伸成放射状两种形态;黄色素细胞较小,含黄色素颗粒;虹彩细胞最小,含鸟粪素颗粒.半滑舌鳎 POMC基因的cDNA序列长910 bp,包括一个114 bp的5'非翻译区和一个154 bp的3'非翻译区,开放阅读框长度为642 bp,共编码213个氨基酸,包含ACTH、α-MSH、β-MSH、γ-LPH、β-内啡肽5个多肽序列,但缺失γ-MSH和大部分连接区.半滑舌鳎POMC基因的氨基酸序列与其他鱼类的同源性为30%-64%.定量PCR分析显示,POMC mRNA主要在垂体中表达,其次是脑、性腺和无眼侧黑化皮肤.正常与黑化皮肤中的差异表达结果显示,无眼侧黑化皮肤中POMC mRNA表达量最高,并与有眼侧皮肤和无眼侧正常皮肤中的POMC mRNA表达量差异显著,揭示了POMC的表达与无眼侧黑化性状密切相关.     

圆斑星鲽仔稚鱼色素细胞发育和体色变化

为研究圆斑星鲽早期发育过程中色素细胞的形态和分布,实验对1~72日龄的圆斑星鲽鱼苗进行了连续的显微观察,并绘制了早期发育生长曲线。结果显示,圆斑星鲽从20日龄开始进入快速的增长期,在水温12~19.5°C时完成变态发育需要50 d,黑色素细胞最早出现,数量最多,黄色素细胞次之,虹彩细胞最后发育,数量最少。变态前黑色素细胞密度先升高后降低,在9日龄密度最大为1390个/mm~2,色素细胞逐渐密集鱼体两侧对称分布;变态开始后鱼体两侧色素不对称,有眼侧体表黑色素细胞逐渐溶解消退,由成体黑色素细胞代替,体色变深,黑色素细胞密度稳定在150个/mm~2;无眼侧黑色素细胞逐渐消溶退化,体色逐渐变白。白化个体在变态开始后出现,有眼侧不能形成成体黑色素细胞,形成白化。     

异源和同源dmrt1基因过表达载体在青鳉体内的整合和表达

利用半滑舌鳎(Cynoglossus semilaevis)dmrt1基因和青鳉(Oryzias latipe)dmrt1基因构建过表达载体,采用显微注射技术将两种载体分别导入青鳉受精卵中,比较异源和同源dmrt1基因对青鳉胚胎孵化率的影响以及两种dmrt1基因在青鳉体内的基因整合率、基因表达率及对芳香化酶基因(cyp19a)表达的影响。结果表明,注射48 h后,两种载体均在胚胎内大量表达,注射青鳉同源性dmrt1载体的受精卵孵化率(69.5%)要显著高于注射异源性dmrt1载体的受精卵(36.5%)。30 dph(days post hatching)两组被注射稚鱼均能检测到基因整合,注射同源dmrt1的整合率(30%)要高于异源dmrt1(10%)。30 dph稚鱼体内检测不到异源性dmrt1载体的表达,但能检测到同源dmrt1载体的mRNA表达,同时芳香化酶基因的表达受到了抑制。本研究为研究舌鳎性别分化相关基因功能提供了基础,并为在模式鱼类中研究海水鱼相关基因功能累积了必要的资料。     

锦鲤早期发育过程中色素代谢相关酶的活性和基因表达变化

通过显微观察、酶联免疫吸附及荧光定量PCR等方法,探究了红白、红黑锦鲤(Cyprinus carpio var. koi)子一代(F_1)早期体色发育过程及不同发育时期色素代谢相关酶(酪氨酸酶、胱氨酸酶)的活性和基因(agouti、mc1r、mitf、tyr)的表达变化。结果表明,锦鲤出膜后呈淡黄色半透明,黑色素细胞在出膜8 d后开始出现。胱氨酸酶活性随锦鲤发育呈升高趋势,出膜7 d后显著升高(P0.05);7日龄仔鱼前,红黑组与红白组间无显著差异(P0.05);出膜7 d后红黑组比同时期红白组显著升高(P0.05)。酪氨酸酶在锦鲤发育过程中也呈升高趋势,但略有起伏,眼色素积累期及出膜23 d后酪氨酸酶活性均比相邻各期高(P0.05);组间比较发现发育各期红黑组均比红白组高(P0.05)。表明酪氨酸酶、胱氨酸酶活性变化与锦鲤色素细胞发育存在密切关联。agouti、mc1r、mitf及tyr 4个基因均在原肠期与神经胚期时表达最高(P0.01),随后均呈下降趋势,表明这4个基因可能在胚胎发育早期的体色形成过程中发挥着重要作用。     

日本无针乌贼胚胎期眼部发育相关基因的研究

为探究日本无针乌贼胚胎期眼部发育的相关调控机制,通过基因功能分析,从前期试验构建的日本无针乌贼胚胎发育期转录组数据库中筛选出与眼部发育密切相关的SIX Homeonox 3 (six3)、Eyes Absent (eya)、及Paired Box 6 (pax6)基因,采用荧光定量PCR分析3个基因在胚胎发育的3个时期——眼原基形成期(SJ1)、功能器官分化期(SJ2)、幼体孵化期(SJ3)8个阶段中相对表达量及变化趋势。试验结果显示,这3个基因在胚胎不同发育期均有不同程度的表达。其中,six3、eya基因从眼原基形成期到幼体孵化期表达量呈上升趋势,并随胚胎发育而显著增加;pax6基因相对表达量从眼原基形成期到功能器官分化期呈上升趋势,而从功能器官分化期到幼体孵化期呈逐渐下降趋势。试验结果表明,six3、eya、pax6基因在基因转录控制网络中发挥不同调节作用,对调控胚胎期眼部发育有重要意义。     

Deficient melanin production contributes to the absence of melanophores in early development of red carp

Red carp and red crucian carp are ornamental fish with a red body color. Unlike in red crucian carp, no melanophores are observed in red carp embryos or larvae. To explore the roles of the mitfa gene in body color formation in red carp, we investigated the structural characteristics and physicochemical properties of the mitfa gene in 16 kinds of fish. The mitfa amino acid sequence similarity between red carp and red crucian carp was 95.6%, and this was 91.5% similar between carp and zebrafish. Compared with red crucian carp, red carp showed lower tyrp1 messenger ribonucleic acid (mRNA) expression but similar mitfa mRNA expression in the body pigment stage of the embryo. Moreover, mitfa⁺ cells as well as melanocytes could be observed in cultured embryo cells derived from red carp and red crucian carp. Our data show that the absence of melanophores in red carp is not the result of mitfa gene deletion or mutation, increasing our understanding of the molecular and genetic mechanisms of coloration in cyprinid fish.     

Spontaneous melanotic lesions in axillary seabream,Pagellus acarne (Risso)

In this article, we describe spontaneous melanotic lesions in the skin of axillary seabream, Pagellus acarne (Risso), from a defined area of the Portuguese Coast, located in Cabo da Roca and Foz do Arelho. The lesions corresponded to the black pigmentation spots on the skin of the head, fins, lips and conjunctiva and, additionally, black nodules on the skin of the head and lips. In some specimens, the nodular formations in the head changed their anatomical conformation. Histologically, there were melanophores scattered along the basement membrane or forming aggregates in the dermis, infiltrating the subcutaneous tissue but not invading the adjacent muscle tissue. The aim of this study was to characterize the macroscopic and microscopic features of the pigmented lesions. These fish show sessile hyperpigmented lesions (spots) that correspond to proliferative lesions of melanophores in the dermis and nodular lesions that correspond to neoplastic lesions, melanophoromas. The melanophores in such lesions showed high concentration of melanin in the cytoplasm, moderate pleomorphism and compact distribution throughout all of the dermis.     

Expression patterns of acidic and basic fibroblast growth factor in loach fish embryos

Heparin-binding fractions were taken from the heparin sepharose columns on which extracts of loach fish (Misgurnus anguillicaudatus) embryos from blastula, gastrula, 4–8 and 12–16 somites stages were applied. These heparin-binding fractions, except the fraction derived from 12–16 somite embryos, showed potent mitogenic activity on fibroblast-like cells derived from caudal fin blastema of goldfish. Western blot analysis of these heparin-binding fractions was carried out using monoclonal antibodies against human acidic and basic fibroblast growth factors (FGF-1 and-2). An immunoreactive FGF-1 band at 16 kD was detected in the heparin-binding fraction derived from embryos in each stage of blastula, gastrula and 4–8 somites. An immunoreactive FGF-2 band at 17 kDa was detected exclusively in the heparin-binding fraction derived from 4–8 somite embryos. In the heparin-binding fraction derived from 12–16 somite embryos neither immunoreactive FGF-1 nor-2 member band was detectable.     

Anaesthetic efficacy of eugenol on iridescent shark,Pangasius hypophthalmus (Sauvage, 1878) in different size classes

Anaesthetic efficacy of eugenol was investigated on iridescent shark, Pangasius hypophthalmus. Fish (2, 5, 10 and 20 g) subjected to 20–200 mg L^?1 eugenol and behavioural response as well as induction and recovery times were recorded. Induction and recovery times were significantly affected by eugenol concentration as well as fish weight (P < 0.05). Generally, 27–300 s after exposure to 20–200 mg L^?1 eugenol, iridescent sharks reached stage 3 anaesthesia (suitable for general handling). Fish entered stage 4 anaesthesia (suitable for surgery and blood sampling) over 54–710 s exposure to such concentrations. Recovery time was 109–600 s in all weight classes as well as eugenol concentrations. Mortality (44–100%) was only observed in 2 g fish when subjected to 110–170 mg L^?1 eugenol. This study, for the first time, showed behavioural response of iridescent shark to anaesthesia as well as effectiveness of eugenol as anaesthetic in this important aquaculture‐ornamental species. According to the models obtained in this study, minimum eugenol concentrations to induce anaesthesia over less than 3 min were 53.8–81.5 mg L^?1 in 2–20 g fish. Likewise, maximum eugenol concentrations in which fish recovered over less than 5 min were 65.9–105.8 mg L^?1 in 2–20 g fish.     

Dual appearance of xanthophores,and ontogenetic changes in other pigment cells during early development of Japanese flounder <Emphasis Type="Italic">Paralichthys olivaceus</Emphasis>

Flatfishes display a left–right asymmetry that is unique in the animal kingdom. In order to clarify the mechanisms of the asymmetrical development of pigment cells, changes in pigment cell densities were examined in Japanese flounder Paralichthys olivaceus. During development from symmetrical larvae to asymmetrical juveniles, pigment cell densities were monitored on the skin on both the left side (ocular side in juvenile; eventually has two eyes) and the right side (blind side in juvenile; eventually has no eyes). A symmetrical and constant decrease was observed in leucophores and larval type melanophores. A mostly symmetrical (slightly delayed on the blind side) and constant increase in iridophores from metamorphosis was observed. Adult-type melanophores appeared and then increased only after metamorphosis on the ocular side. However, the pattern of xanthophores was complicated: they first existed symmetrically and decreased symmetrically until metamorphosis, and they later increased only on the ocular side. The dual appearance of the xanthophores, as well as the differences between their depths and sizes on the ocular and blind sides, may suggest the presence of two types of xanthophores—just as melanophores are well known to exhibit two types. The ontogenetic study of pigment cells described here is likely to help to elucidate the process of abnormal pigmentation in flatfishes.     

Prostanoids-induced dispersion in the melanophores of a carp Labeo rohita (Ham.)

Effects of three prostaglandins (i.e., prostanoids) and one of its precursors, arachidonic acid, were examined on the melanophores of the fish Labeo rohita (Ham.). PGE₁, PGE₂, PGF_2α and arachidonic acid elicit a concentration-related dispersion in the fish melanophores. In vitro analysis of melanophores was performed through incubation of the isolated fish scales in different agonists and antagonists solutions. Dispersal effect of prostanoids may be mediated directly through the typical receptors or indirectly through release of neurotransmitter substance(s) from the melanophore nerve endings. Denervation of fish melanophores rendered them insensitive to prostanoid (PGF_2α). Propranolol and verapamil completely inhibited the dispersal effects of PGF_2α; theophylline and indomethacine blocked the effects of higher concentrations of PGF_2α. During dispersing influence of PGF_2α, a free flux of Ca²⁺ ions was required and the indirectly released substance(s) from melanophore nerve endings would be the catecholamines of adrenergic and purinergic in nature.     

Preliminary investigation to determine the toxicity of various cryoprotectants on striped gourami (Trichogaster fasciata) embryos

As a study of cryoprotectant toxicity is an essential prerequisite for the development of a cryopreservation protocol, this study focuses on determining the toxicity of four permeable cryoprotectants: dimethyl sulfoxide (DMSO), propylene glycol (PG), methanol (MeOH), and acetamide (Ac). In cryoprotectant toxicity experiments, striped gourami (Trichogaster fasciata) embryos at three different developmental stages (multi cell, 100% epiboly, and proliferation of somites) were exposed to cryoprotectant solutions with concentrations from 1 to 4 M for a period of 5 and 15 min. Following these treatments, the embryos were incubated until the evaluation of hatching rate. Embryos were tolerant to low concentrations of all cryoprotectants tested in the range of 1 to 2 M for all developmental stages. Early stage embryos were more vulnerable to high concentration (3 and 4 M) than late stage embryos. Results also showed that as concentration and duration of exposure increased, the hatching rate significantly decrease (P < 0.05). On a molar-equivalent basis, DMSO appeared to be less toxic to PG, MeOH, and Ac in general. Exposure to cryoprotectants revealed a stage-dependent sensitivity. Toxicity increased in the order of MeOH < DMSO < PG < Ac in multi cell stage and DMSO < MeOH < PG < Ac in 100% epiboly and proliferation of somites stages. The proliferation of somites stage embryos was less sensitive to exposure to cryoprotectants than multi cell and 100% epiboly stages. These findings could be important for designing cryopreservation protocols for this demanding ornamental species.

     

Effects of dietary oxidized fish oil on growth performance and skin colour of Chinese longsnout catfish (Leiocassis longirostris Günther)

A 61‐day experiment was carried out to investigate the effect of dietary oxidized fish oil on growth performance and skin colour of Chinese longsnout catfish (Leiocassis longirostris Günther). Seven diets (Diet 1–7) containing different levels of oxidized fish oil (0, 10, 20, 30, 40, 50 and 60 g kg^?1 dry diet) were evaluated at same dietary lipid level (60 g kg^?1 diet). Fish skin colour (CIE L*a*b*) and melanin content was measured at three zones of fish body: back (Zone I), belly (Zone II) and tail (Zone III). The results showed that there were no significant differences in growth or feed utilization. Apparent digestibility coefficient of energy (ADCe) decreased while those of dry matter (ADCd), protein (ADCp) or lipid (ADCl) were not affected. Lightness (L*) of Zone I or II were not influenced while L* of Zone III decreased. Oxidized oil increased melanin content of Zone III. No apparent effects on the thiobarbituric acid reactive substances (TBARS) values of blood serum, liver and muscle were observed. In conclusion, dietary oil oxidation did not affect fish growth performance. Fish tail skin lightness was lower in the fish fed with high dietary oxidized fish oil and was positively correlated to melanin content.     

The effect of different carotenoid sources on skin coloration of cultured red porgy (Pagrus pagrus)

This study presents data on the effect of carotenoid sources on skin coloration of red porgy (Pagrus pagrus). Three experiments were conducted: in the first, fish were fed an astaxanthin (Naturose^®)‐supplemented diet, while the second fish received diets supplemented with β‐carotene (Rovimix β‐caroten^®) or lycopene (Lyc‐O‐Mato^®): Carotenoids were added to the level of 100 ppm in each diet, while a non‐carotenoid‐supplemented diet served as a control. In the third experiment, the effect of dietary protein/carbohydrate ratio on melanin content in the skin was investigated. For this experimentation, four diets were formulated to contain 50/23, 40/32, 30/48 and 20/59 protein/carbohydrate ratio. Naturose^® astaxanthin increased total carotenoid content in the dorsal skin area while β‐carotene and lycopene seem to have had no significant effect. Naturose^® was the only carotenoid source that had a significant effect on skin hue, promoting a reddish coloration to the dorsal skin area and a ventral hue similar to wild red porgy. No apparent effect of carotenoid source on skin melanin content was observed. In contrast, dietary protein/carbohydrate ratio affected melanin content in the skin. The fish fed the 50/23 diet showed significantly higher values. Farmed red porgy had eight times higher dorsal‐skin melanin content than wild ones.