大黄鱼消化道菌群结构、消化酶和非特异性免疫酶活力分析

为研究大黄鱼(Larimichthys crocea)消化道的菌群结构、消化酶和非特异性免疫酶活力特征,本研究采用高通量测序技术系统分析大黄鱼胃、幽门盲囊和肠道中菌群组成及分布,并对比研究工厂化养殖和网箱养殖模式下的消化道菌群;同时,结合生化分析方法解析2种模式下消化道消化酶和非特异性免疫酶活力特征。结果显示,2种养殖模式下,菌群多样性随消化道延伸呈下降趋势;乳杆菌科(Lactobacillaceae(f))、Fructobacillus、黄杆菌属(Flavobacterium)等代表的菌属为共有优势菌群。其中,拟杆菌属(Bacteroides)和Anaerostipes等的丰度随消化道延伸呈下降趋势,而乳杆菌科、E01_9C_26_marine_group(o)所代表的菌属及黄杆菌属等则相反;普氏菌属(Prevotella_9)、乳杆菌科代表的菌属为2种模式养殖大黄鱼的主要差异菌属。工厂化养殖条件下,幽门盲囊和肠道中的菌群组成及其参与营养和免疫相关代谢通路的基因数目差异不显著(P>0.05),但与胃部的菌群组成和相关代谢通路基因数目存在明显差异;而网箱养殖大黄鱼胃部与幽门盲囊和肠道的菌群结构及相关代谢通路基因数目差异相对较小。2种养殖模式下的大黄鱼消化道菌群与饲料菌群相近。另外,胃和幽门盲囊也具有非特异性免疫酶活性,说明,整个消化道还具有一定的化学免疫屏障作用。本研究结果将为大黄鱼健康养殖提供基础参考,并为消化道菌群生理功能探讨提供理论依据。     

工厂化养殖密度对黄条鰤生长和生理特性的影响

养殖密度是水产养殖管理中一项非常重要的参数, 适宜的养殖密度能够降低养殖动物的应激胁迫水平, 促进其健康、快速生长。为探究黄条鰤(Seriola lalandi)在陆基工厂化养殖条件下的最适密度, 本研究对 1 龄黄条鰤 [(565.83±70.22) g]开展为期 60 d 的养殖实验, 共设置 10 尾/m³ (低密度组)、20 尾/m³ (中密度组)和 30 尾/m³ (高密度组) 3 个密度组。实验过程中测量并计算包括增重率、特定生长率、肥满度和肝体指数在内的生长指标, 并检测血液生理、血清生化、肝脏和肾脏组织的非特异性免疫酶活性等指标。结果表明, 中、高密度组黄条鰤的增重率、 特定生长率在第 60 天时均显著低于低密度组对应的数值(P＜0.05); 在 3 个密度组中, 低密度组的特定生长率在 60 d 时显著高于 30 d 的数值(P＜0.05), 中密度组的特定生长率在 60 d 与 30 d 之间差异不显著(P＞0.05), 高密度组的特定生长率在 60 d 时低于 30 d 的数值, 说明高密度养殖对黄条鰤的生长产生了的胁迫。整个实验过程中, 血清中肾上腺素和皮质醇等的含量在 30 d 和 60 d 时均随养殖密度的增加而显著升高(P＜0.05), 生长激素和类胰岛素生长因子 Ⅰ的含量呈相反趋势; 肝脏和肾脏中超氧化物歧化酶、溶菌酶、谷丙转氨酶、谷草转氨酶、酸性磷酸酶、碱性磷酸酶和丙酮酸激酶的活性在 30 d 和 60 d 时整体呈现随养殖密度的增加而显著升高的趋势(P＜0.05), 说明高密度养殖对黄条鰤的生理造成了胁迫。由此可见, 从生长、生理和生产实践角度综合评价, 中密度(20 尾/m³ )是 1 龄黄条鰤工厂化养殖的适宜密度, 相关研究结果将为黄条鰤工厂化养殖技术进一步完善提供参考。     

营养代谢过程中黄条鰤幼鱼消化道菌群的演变趋势

为认识消化道菌群结构在宿主营养代谢过程中的变化规律,并探讨饵料菌群对其的影响,采用16SrDNA高通量测序技术,对黄条鰤(Seriola lalandi)幼鱼一个完整摄食周期内的消化道菌群结构特征进行研究,并解析其与饵料菌群的相关性.结果显示,乳杆菌属(Lactobacillus)、假单胞菌属(Pseudomonas)...     

5-HMF对黄条鰤生长、肠道组织结构及生理特性的影响

为了分析在饲料中添加 5-HMF (5-羟甲基糠醛)对黄条鰤(Seriola aureovittata)幼鱼生长、肠道组织结构、血清生化特性、消化道菌群结构等方面的影响, 选用 360 尾平均体重(82.33±2.75) g 的黄条鰤, 随机分为 4 组(M0 组、 M1 组、M2 组、M3 组), 每组 3 个重复, 每个重复 30 尾鱼, M0 组为对照组, 投喂基础饲料, M1 组、M2 组、M3 组分别投喂添加 5-HMF (添加量分别为 0.25%、0.5%、1%)的基础饲料, 实验持续 6 周。结果显示: 体外 Caco-2 细胞(人结直肠腺癌细胞)增殖实验表明, 本研究所用 5-HMF 浓度在安全范围内; M2 和 M3 组实验鱼的增重率和特定生长率显著高于 M0 组(P＜0.05), 且 M2 组肥满度显著高于 M0 组(P＜0.05); M2 组实验鱼肠道肌层厚度和绒毛高度显著高于 M0 组(P＜0.05); M2 和 M3 组血清中谷胱甘肽过氧化物酶(GSH-Px)、超氧化物歧化酶(SOD)和过氧化氢酶 (CAT)活性显著高于 M0 组(P＜0.05), 而丙二醛(MAD)水平显著降低(P＜0.05); M2 和 M3 组实验鱼血清免疫球蛋白 M (IgM)和碱性磷酸酶(AKP)水平显著高于 M0 组(P＜0.05); M2 组血清溶菌酶(LZM)和酸性磷酸酶(ACP)活性显著高于 M0 组(P＜0.05); 在 M0 组幽门盲囊微生物 Chao1 指数显著高于 M1 组(P＜0.05), 而 M2 组肠道微生物的 Shannon 指数显著高于 M0 和 M1 组(P＜0.05)。综上所述, 饲料中添加 0.5%的 5-HMF 实验饲料可以提升黄条鰤幼鱼生长性能, 提高血清免疫酶活水平和抗氧化能力, 对肠道组织和菌群结构起到一定的优化调节作用, 可为开发黄条鰤健康养殖技术和绿色饲料添加剂提供理论支撑。     

三种鰤属鱼类肌肉质构特性及营养成分比较分析

为分析我国养殖黄条鰤(Seriola lalandi)、高体鰤(S. dumerili)、五条鰤(S. quinqueradiata)肌肉的质构特性、基本营养组成和食用价值, 采用质构分析法(TPA)和常规生化方法检测了 3 种鰤属鱼类肌肉的质构特性、粗蛋白、脂肪酸和氨基酸等成分, 并评价了营养价值。结果显示: 同等养殖条件下, 黄条鰤肌肉的硬度、胶着度、咀嚼度和回复力均显著高于高体鰤和五条鰤。黄条鰤肌肉蛋白含量(24.3%)最高, 高体鰤水分含量(70.6%)最高, 五条鰤脂肪含量(7.2%)最高, 3 种鰤属鱼类肌肉的必需氨基酸含量均优于 FAO/WHO 标准。根据 AAS 和 CS 分值, 3 种鰤属鱼类肌肉的第一限制氨基酸皆为蛋氨酸, 第二限制氨基酸皆为缬氨酸, 且肌肉鲜味氨基酸含量及其在总氨基酸中的占比均较高, 这与其味道鲜美密切相关。3 种鰤属鱼类肌肉中可检测到 20 种脂肪酸, 其中亚麻酸甲酯(C18 3n6) ∶ 只在五条鰤中检测出, 二十二碳二烯酸甲酯(C22 2) ∶ 只在高体鰤中检测出。肌肉的不饱和脂肪酸含量(65.44%~67.51%)均相对较高, 其中不饱和脂肪酸 EPA+DHA 的含量(32.50%~35.79%)优势明显。另外, 高体鰤中的常量元素含量 (5.27×10³ mg/kg)最高, 五条鰤中的微量元素含量(15.931 mg/kg)最高。本研究表明, 3 种鰤属鱼类肌肉中含有丰富的氨基酸和脂肪酸等营养物质, 是极具市场开发潜力的大洋性养殖经济鱼种, 研究结果将为我国鰤属鱼类养殖潜力评价和专用高效配合饲料的研制提供参考依据。     

基于稳定同位素分析的野生黄条鰤食物组成研究

通过检测工厂化养殖黄条鰤(Seriola aureovittata)各组织(肝脏、肠、心脏、鳃和肌肉)及饵料鱼的碳同位素比值(δ~(13)C),获得黄条鰤各组织的碳同位素判别值(Δ13C),结合大连海域野生黄条鰤及其潜在食物的δ~(13)C值,推测黄条鰤的食物来源。结果表明:工厂化养殖黄条鰤各组织Δ13C依次为肌肉(1.00‰)鳃(0.98‰)心脏(0.95‰)肠(0.79‰)肝脏(0.37‰)。大连海域野生黄条鰤的46种可能饵料生物的δ~(13)C为-21.61‰~-16.84‰。通过工厂化养殖黄条鰤肌肉组织的Δ13C,推测大连海域野生黄条鰤的食物组成以中上层鱼类为主,其次为中下层鱼类、底层鱼类、游泳虾形类、蟹类、头足类,其平均贡献率依次为64.0%、9.8%、9.0%、6.2%、5.1%、3.7%。     

不同养殖模式黄鳝胃肠道微生物群落结构分析

为探究不同养殖模式下黄鳝(Monopterus albus)胃肠道微生物的群落结构，本实验采用16S rRNA高通量测序技术研究虾塘散养、蟹塘散养、网箱投喂鱼浆和网箱投喂水蚯蚓4种养殖模式下黄鳝胃肠道微生物的组成和群落结构。Alpha多样性分析和Venn图结果显示，网箱投喂水蚯蚓组黄鳝胃肠道微生物多样性和丰度均较高，而蟹塘散养组最低。除蟹塘散养组黄鳝肠道的优势菌为变形菌门，其余3种养殖模式黄鳝胃肠道优势菌群均为厚壁菌门，推测黄鳝胃肠道微生物的核心菌群为厚壁菌门。在属水平上，网箱投喂水蚯蚓养殖模式中黄鳝胃的优势菌群为粪杆菌属(Faecalibacterium)与嗜黏蛋白阿克曼菌属(Akkermansia),其余3种养殖模式中黄鳝胃的优势菌群都为韦荣球菌属(Veillonella);而虾塘散养组黄鳝肠道的优势菌群为瘤胃球菌属(Ruminococcus),其余3种养殖模式的优势菌群中都有双歧杆菌属(Bifidobacterium)。结果表明：网箱投喂水蚯蚓组黄鳝胃肠道微生物多样性和丰度均较高，且益生菌群占比高，潜在致病菌较少，是比较健康的养殖模式。     

达氏鳇和施氏鲟生长差异群体肠道菌群特征

同塘生长差异常常导致鲟养殖产量受损, 而肠道菌群是影响鱼类生长性能的关键因素之一。为揭示肠道菌群与鲟科鱼类个体生长差异之间的关系, 本研究对同批次繁育、同条件养殖的生长速率差异大于体重 50%的达氏鳇 (Huso dauricus)和施氏鲟(Acipenser schrencki)群体进行了肠道菌群特征研究。结果表明, 达氏鳇和施氏鲟肠道菌群多样性和组成在种属间及生长差异群体间均具有明显差异。其中, 生长快速达氏鳇群体(LH)肠道优势菌属为鞘氨醇单胞菌属(Sphingomonas, 67.0%), 生长慢速达氏鳇群体(SH)肠道优势菌属为鞘氨醇单胞菌属(29.5%)和狭义梭菌属 1 (Clostridium sensu stricto 1, 54.2%); 而生长快速施氏鲟群体(LA)肠道优势菌属为鞘氨醇单胞菌属(33.5%)和鲸杆菌属(Cetobacterium, 38.1%), 生长中速施氏鲟群体(MA)肠道优势菌属为鞘氨醇单胞菌属(42.6%)、狭义梭菌属 1 (14.3%)和鲸杆菌属(33.0%)。鞘氨醇单胞菌属和梭菌科(Clostridiaceae)细菌是不同生长速率鲟肠道中的主要差异类群。综上可知, 鲟科鱼类肠道菌群的多样性和组成具有种属差异性和群体差异性, 鞘氨醇单胞菌属和梭菌科细菌可能是影响鲟科鱼类生长速率的关键细菌类群。     

黄尾鰤的生物学特性与养殖

介绍了黄尾鰤的分布、形态特征、生活习性、繁殖与生长特性等生物学知识;对黄尾鰤亲鱼的促熟培养、产卵孵化和仔鱼培育技术进行了综述;概述了目前国外两种主要养殖方式即网箱养殖和陆基(工厂化)养殖的技术要求。     

黄条鰤不同组织碳稳定同位素的转化率与分馏

在水温18.79~22.15℃的实验室条件下,给体质量(34.2±1.8)g的黄条鰤Seriola aureovittata投喂已知碳源的冰鲜玉筋鱼Ammodytes personatus肌肉,研究黄条鰤不同组织碳稳定同位素的转化率差异及分馏系数,以探讨组织生长和代谢对不同组织碳稳定同位素转化的相对贡献。结果表明,黄条鰤各组织碳稳定同位素半衰期从小到大依次为肝脏(3.2d)、肠(3.4d)、鳃(3.6d)、心脏(5.5d)、肌肉(6.4d),各组织与饵料间的碳稳定同位素富集系数(△δ~(13)C)从小到大依次为肝(0.15‰)、肠(0.48‰)、心脏(0.98‰)、鳃(1.02‰)、肌肉(1.08‰)。代谢作用对肝脏和肠组织的碳稳定同位素转化率的贡献占主导地位(60%),生长作用对其贡献相对较小。肝脏和肠组织可反映黄条鰤短期内的摄食特征,而肌肉组织则可反映较长时间的摄食特征。本研究结果可丰富黄条鰤基础生物学内容,为不同时间尺度的稳定同位素研究取样和工厂化养殖中的营养强化、饵料选择等提供参考。     

Temperature and dissolved oxygen influence growth and digestive enzyme activities of yellowtail kingfish Seriola lalandi (Valenciennes, 1833)

A 5 week experiment was carried out with juvenile yellowtail kingfish Seriola lalandi to investigate the interactive effects of water temperature (21, 24, or 27°C) and dissolved oxygen regime (normoxic vs. hypoxic) on the growth rate, feed intake and digestive enzyme activity of this species. Specific growth rate (SGR) was highest at 24°C, regardless of oxygen regime, but the SGRs of the fish exposed to hypoxia at 21, 24 and 27°C were 13%, 20% and 17% lower, respectively, than the SGRs recorded for the fish reared under normoxic conditions. The digestive enzyme activities (i.e. trypsin, lipase and α‐amylase) were influenced by temperature but did not appear to be affected by dissolved oxygen concentration. Information about the effects of water temperature and dissolved oxygen on feeding, growth and digestive capacity of juvenile yellowtail kingfish could contribute to improving feed management decisions for production of this fish species under different environmental conditions.     

Structural characteristics and succession of intestinal microbiota for Paralichthys olivaceus during the early life stage

The research of intestinal microflora structures for Paralichthys olivaceus larvae and juveniles will help us to master the ontogeny and developmental colonization of microflora during the larval rearing stage. In this study, we sequenced the total bacterial genomic DNA in larval and juvenile guts with an Illumina MiSeq PE300 system, and analysed the structural characteristics of these microbiota, feed and rearing water in live and formulated feeding periods. The structure of gut microbiota was gradually similar to those in wild P. olivaceus at the phylum level and the newly hatched ones with the growth, according to the distribution and abundance of intestinal microbiota. And the colonized rule of main microbial species in guts was decreased initially and then increased during the larvae and juveniles stage. Meantime, the core microflora of this study were obtained through the analysis of shared and dominant species, which included Bacteroides, Bacillus, Enterococcus, Lactobacillus, Lactococcus, Escherichia_Shigella, Acinetobacter, Pseudomonas, Vibrio, Nitrosomonas, and Glaciecola. The correlation analysis of microbiota between intestines and environmental factors suggested that microflora in feed and water could affect the distribution of larval and juvenile gut microbiota. Moreover, many species of Acinetobacter, Pseudomonas and Vibrio are treated as important potential pathogens in aquaculture. These all pointed out the microbial quality of feed and rearing water should be strictly controlled in fish breeding and farming, and supply theoretical bases for screening the native probiotics to artificially regulate the gut microbiota.     

Immune Responses to Vibrio anguillarum in Yellowtail Kingfish,Seriola lalandi,Fed Selenium Supplementation

Effects of dietary selenium (Se) on immune competence of yellowtail kingfish, Seriola lalandi, were investigated. The fish were fed one of the three experimental diets including a control diet without Se supplementation and two diets supplemented with Se from Se‐yeast (Selplex) at 2 and 4 mg/kg. After feeding for 6 wk, the fish were challenged by injecting Vibrio anguillarum and observed for 2 wk. Dietary Se had no effect on feed intake, feed conversion ratio, and survival over the course of 6‐wk feeding; however, it significantly increased weight gain and Se content in muscle. Following the bacterial infection, the immune‐stimulating effects of Se were observed in antibody, lysozyme, and bactericidal responses, and there was a corresponding increase in survival and hematocrit by Se. Under infectious condition, antioxidant capacity of fish as measured in terms of resistance of red blood cells to peroxidation and glutathione peroxidase activity also increased by supplementation of Se. Liver necrosis and kidney melano‐macrophages were only seen in surviving fish fed the control diet after the challenge. Furthermore, there was evidence of myopathy in fish fed the diet without Se supplementation. This study suggests that Se, supplemented at 2 or 4 mg/kg, can improve growth and health of yellowtail kingfish.     

Do swimming fish always grow fast? Investigating the magnitude and physiological basis of exercise-induced growth in juvenile New Zealand yellowtail kingfish, <Emphasis Type="Italic">Seriola lalandi</Emphasis>

There is a wealth of evidence showing that a moderate level of non-stop exercise improves the growth and feed conversion of many active fishes. A diverse number of active fish are currently being farmed, and an optimal level of exercise may feasibly improve the production efficiency of these species in intensive culture systems. Our experiments have set out to resolve the growth benefits of juvenile New Zealand yellowtail kingfish (Seriola lalandi) enforced to swim in currents at various speeds over two temperatures (14.9 and 21.1°C). We also probed potential sources of physiological efficiency in an attempt to resolve how growth is enhanced at a time of high energetic expenditure. Results show that long-term exercise yields a 10% increase in growth but this occurs in surprisingly low flows (0.75 BL s⁻¹) and only under favourable environmental temperatures (21.1°C). Experiments using a swim flume respirometer indicate that exercise training has no effect on metabolic scope or critical swimming speeds but it does improve swimming efficiency (lower gross costs of transport, GCOT). Such efficiency may potentially help reconcile the costs of growth and exercise within the range of available metabolic energy (scope). With growth boosted in surprisingly low flows and elevated water temperatures only, further investigations are required to understand the bioenergetics and partitioning of costs in the New Zealand yellowtail kingfish.     

Quantification of waste feed and fish faeces in sediments beneath yellowtail pens and possibility to reduce waste loading by co‐culturing with sea cucumbers: an isotopic study

To evaluate environmental impacts of yellowtail culture and to examine the efficiency of the sea cucumber Apostichopus japonicus in reduction of waste loading, surface sediments were sampled and A. japonicus were cultured at a yellowtail farm in Owase Bay, Japan. Waste feed‐ and faeces‐derived organic matter (WOM, FOM) in sedimentary organic matter (SOM) was estimated based on the δ¹³C and δ¹⁵N of the fish feed (?21.7‰, 9.2‰), yellowtail faeces (?20.6‰, 6.2‰) and SOM reference (?24.4‰, 4.4‰). Small WOM (0–22% in SOM) but substantial FOM (28–61%) loadings in the fish farm area and high sulphide concentrations in the sediments (1.0 mg g^?1) suggest that reduction in the fish stocks or mitigation of the faeces should be considered. A. japonicus juveniles were cultured in three cages deployed below a pen and growth was assessed after three different periods (62, 107, 181 days). A. japonicus grew well during the first 107 days (daily specific growth rate, 3.7%) and their survivorship was high (80–90%). Growth ceased after 107 days, probably due to fouling on the cages. The δ¹³C and δ¹⁵N of their hypothetical diet (–19.7‰, 5.5‰) were close to the FOM values, suggesting assimilation of FOM.     

Effects of variation in dietary contents of selenium and vitamin E on growth and physiological and haematological responses of yellowtail kingfish,Seriola lalandi

The effects of dietary selenium (Se) and vitamin E and their interaction in the nutrition of yellowtail kingfish, Seriola lalandi, were investigated. Six dietary treatments were prepared in a 3 × 2 factorial arrangement (not supplemented or supplemented with Se at 1 or 2 mg kg^?1 × supplemented with vitamin E at 40 or 180 mg kg^?1). A group of fish in triplicate were fed one of the six experimental diets for 6 weeks, and their growth performance, haematological and immune responses were measured. The results revealed positively interactive effects between dietary Se and vitamin E in yellowtail kingfish. Se significantly increased weight gain of fish fed diets low in vitamin E, but not high in vitamin E. Simultaneous supplementation of both micronutrients resulted in significant increase in serum bactericidal activity. There was no significant effect of Se or vitamin E on survival, feed intake, feed conversion ratio, haematocrit, white blood cell counts and fillet proximate composition. However, Se and vitamin E contents in fillets were significantly responsive to dietary Se and vitamin E, respectively. The supplemental level of Se at 2 mg kg^?1 significantly increased red blood cell counts and haemoglobin concentrations, while lysozyme activity in skin mucus was significantly stimulated by vitamin E. The findings of Se and vitamin E supplementation in this study can be applied to improve growth and health indices of yellowtail kingfish.     

Effects of stocking density and natural food availability on the extensive cage culture of pejerrey (Odontesthes bonariensis) in a shallow Pampean lake in Argentina

An experiment was conducted for 80 days at La Salada de Monasterio Lake (Buenos Aires, Argentina) to assess the effect of stocking density and natural food availability on the growth and production of zooplanktivorous juveniles of pejerrey (Odontesthes bonariensis) in extensive cage culture. Ten cages were installed and stocked with 33‐day‐old fish, at three density treatments: 25, 50 and 75 ind. m^?3. Zooplankton was analysed in terms of abundance, biomass and diversity considering three size classes. Caged pejerrey diet was assessed regularly. The pejerrey gut contents composition was clearly different from cage zooplankton, showing a trend to contain bigger components. Reared fish exhibited a tendency to diversification of the diet and to change the mean prey size depending on fish length and stocking density. Regression models showed a positive and direct effect of the bigger zooplankton biomass on fish growth rates, which were also inversely affected by the availability of smaller zooplankton. The results demonstrate that stocking density and available zooplankton, in both quantity and quality, are key factors in regulating extensive cage culture of pejerrey. Handling stocking densities in a dynamic way it is possible to maximize fish growth, biomass harvest or fish number according to the goals of production.     

Water Quality and Growth of Rohu,Labeo rohita,in a Biofloc System

We evaluated the technical feasibility of reducing water dependency of rohu, Labeo rohita, culture with biofloc under light-limited indoor culture. Biofloc and control treatments were conducted in 700-L indoor tanks at three different stocking densities (STD): 1.3, 2.6, and 3.9 Nos. fish m^?2 of surface area of tank for a period of 90 days. In biofloc treatment, fish were fed 20% crude protein feed and extra organic carbon in the form of wheat flour, whereas in case of control treatment they were fed 30% crude protein feed only. Fish survival was 100% in both the treatments. Lower stocking density produced larger fish, but growth was similar within stocking densities among control and biofloc treatments. The nutritional quality of biofloc was found to be quite suitable for rohu. Frequency of water exchange was significantly less in biofloc treatments as compared to the control ones.     

A comparison of the palatability of racemic praziquantel and its two enantioseparated isomers in yellowtail kingfish Seriola lalandi (Valenciennes, 1833)

The bitterness of racemic praziquantel (Rac‐PZQ) constrains its use as an in‐feed treatment against monogenean flukes in finfish aquaculture. Evidence exists in mammals that the R‐(?) enantiomer of PZQ is less bitter than the S‐(+) enantiomer. If fish exhibit this same response, then the recently described techniques for the large‐scale resolution of R‐(?)‐PZQ from Rac‐PZQ could facilitate the wide‐spread application of this effective anthelmintic compound via feed. The hypothesis that yellowtail kingfish Seriola lalandi would find R‐(?)‐PZQ more palatable than Rac‐PZQ and S‐(+)‐PZQ was tested in four trials. During the first three trials, the palatability of diets top‐coated with 10 g kg^?1 of Rac‐PZQ or its two enantioseparated isomers were compared in small (85–160 g) and large (1.2 kg) yellowtail kingfish. A fourth trial compared the palatability of R‐(?)‐PZQ and Rac‐PZQ at dietary inclusion levels of 2.5, 5.0 and 10.0 g kg^?1 in small yellowtail kingfish (170 g). Ingestion data showed that R‐(?)‐PZQ to be no more palatable than either Rac‐PZQ or S‐(+)‐PZQ to yellowtail kingfish, regardless of size. Indeed, evidence suggested that the S‐(+)‐PZQ to be slightly more palatable than both R‐(?)‐PZQ and Rac‐PZQ. From these data, we hypothesize that the strong smell of R‐(?)‐PZQ (which was not present in S‐(+)‐PZQ) is an equally important determinant to palatability as taste in yellowtail kingfish. Results demonstrate that dietary inclusion level is a more important determinant to palatability than PZQ chirality; however, administration of R‐(?)‐PZQ may still be advantageous if it is demonstrated to be the only enantiomer efficacious against monogeneans.