渔用纳米蒙脱土改性聚乳酸单丝降解性能

为研究纳米蒙脱土(nano-MMT)改性聚乳酸(PLA)单丝在海水环境中的降解特性,试验测试了纯PLA单丝、0.5wt%、1.0wt%nano-MMT/PLA单丝在浙江舟山海域海水中15个月的降解特性。结果显示,纳米蒙脱土改性聚乳酸单丝在海水环境中自然降解9个月时间内,其力学性能和数均分子量下降较为缓慢;当降解时间超过9个月后,改性聚乳酸单丝的断裂强度和数均分子量呈加速下降趋势。表明改性聚乳酸单丝在海水中降解9个月后进入加速降解阶段,推断改性聚乳酸单丝在海水环境中的最佳使用寿命为9个月。加入nano-MMT后,改性聚乳酸单丝力学性能和数均分子量下降较纯聚乳酸单丝要快。在海水中降解15个月后,加入0.5wt%nano-MMT的改性聚乳酸单丝断裂强度和数均分子量分别下降了25.0%和50.0%,而纯的聚乳酸单丝则仅下降了20.4%和30.6%。由于nano-MMT的加入,会使PLA与nano-MMT的界面结合产生缺陷,nano-MMT与聚乳酸大分子链之间的界面结合缺陷会成为水分子进入聚乳酸大分子内部的通道,从而加速改性PLA单丝在海水环境中的降解。同时nano-MMT的加入会加快改性PLA单丝耐磨性的下降趋势,纯PLA单丝在海水中降解15个月后,耐磨度由2.20 F/tex下降为1.32 F/tex,耐磨度下降40%;而0.5wt%nanoMMT/PLA的耐磨度由2.34 F/tex下降为0.70 F/tex,耐磨度下降70.1%。     

MMT改性淀粉基纳米复合纤维的海水降解性能

不可降解渔具造成的“白色污染”和“幽灵捕捞”问题已严重威胁到海洋的生态环境,开发可降解渔具材料已经成为我国渔业可持续发展的有效途径之一。本实验采用熔融纺丝法制备淀粉(STR)/高密度聚乙烯(HDPE)/纳米蒙脱土(MMT)纳米复合纤维,研究MMT对纳米复合纤维的热学性能、力学性能、动态力学性能与海水降解性能的影响。结果显示,引入MMT后,纳米复合纤维的熔融温度(Tm)移向低温,结晶度增加,而断裂强度下降。此外,MMT的加入显著降低了聚乙烯的玻璃态储能模量和内部损耗,但对淀粉相影响不显著。4个月海水降解结果显示,与STR/HDPE纤维相比,STR/HDPE/MMT纳米复合纤维失重率增加了约5%,纤维直径减小了约11%,这表明MMT加快了STR/HDPE纤维的降解过程。本实验系统研究了MMT改性淀粉基纳米复合纤维的海水降解性能,可为渔业等海洋产业用降解新材料的开发与应用提供参考。     

渔用超高分子量聚乙烯/石墨烯纳米复合纤维的结构与蠕变性能

采用熔融纺丝法制备渔用超高分子量聚乙烯(UHMWPE)/石墨烯(GR)纳米复合纤维,研究了GR含量对UHMWPE纤维结构、热性能、力学性能与蠕变性能的影响。结果显示,GR在UHMWPE纤维基体中的分散情况以纳米级厚度为主,当GR含量为1‰和3‰时,GR在UHMWPE纤维基体中分散均匀,当GR含量为5‰时,GR在UHMWPE纤维基体中出现大的团聚体。与纯UHMWPE纤维相比,UHMWPE/GR纳米复合纤维的断裂强度和结节断裂强度均有显著提高,表明一定含量的GR可有效增强UHMWPE的抗蠕变性能且降低其蠕变速率。当GR含量为3‰时,断裂强力提高了31.9%,蠕变率降低了27.3%。当UHMWPE经GR改性后,纳米粒子与聚乙烯链段相互作用力增强,晶区附近受限的非晶区链段增多,α转变峰逐渐增强增宽。研究表明,通过纳米改性技术,可以显著提高超高分子量聚乙烯纤维的力学性能和抗蠕变性能,为实现渔用材料的高性能化提供理论依据。     

渔用聚乙烯纤维研究现状及趋势

系统论述了渔用聚乙烯纤维的研究现状及其发展趋势,结合聚乙烯塑料的改性方法,提出了渔用聚乙烯纤维增强增韧的改性思路。介绍了橡胶或弹性体、刚性粒子、刚性粒子协同弹性体对聚乙烯增强增韧改性方法,重点介绍了刚性粒子和刚性粒子协同弹性体对聚乙烯的增韧改性,指出纳米粒子协同弹性体增韧渔用聚乙烯纤维将是未来渔用聚乙烯纤维增韧改性的主要研究方向。     

渔用可降解材料的研究进展与展望

可降解渔具材料的研发与应用是减轻"幽灵捕捞"、保护海洋渔业资源和生态环境、实现可持续发展的有效途径之一。淀粉基材料、聚己内酯(PCL)、聚乳酸(PLA)、聚丁二酸丁二醇酯(PBS)等材料具有可完全生物降解、可加工、可再生等特点,作为不可降解渔用合成纤维材料的替代品,可为生物降解高分子材料在渔业领域的应用开辟新的途径。主要综述了近年来国内外有关淀粉基材料、 PCL、PLA、PBS 4种渔用可降解高分子材料的性能、生物降解机理及其与天然高分子共混、合成高分子共混改性的研究进展,介绍了加工工艺、表面处理、添加剂等对复合体系性能的影响,并分析了可降解材料在渔业上的应用及发展前景,以期为研发价格低廉、综合性能优越的可降解渔用材料提供参考。     

渔用PP/PA复合单丝和普通PP单丝的耐磨性比较

渔用聚丙烯聚酰胺(PP/PA)复合单丝是东海水产研究所采用共混改性技术及特殊纺丝工艺生产的渔用纤维新材料.课题组在对渔用PP/PA复合单丝和普通聚丙烯(PP)单丝结构和性能前期研究的基础上,对同等加压负荷下两种单丝的磨损质量损失、耐磨度、强度保持率以及伸长变化进行了比较,揭示了单丝材料的结构与耐磨性之间的关系.在相同加...     

可生物降解PLA刺网与传统PA刺网的物理性能和捕捞效率的比较分析（英文）

为了保护海洋生态环境,减少遗弃的不可降解渔网造成的"白色污染"及"幽灵捕捞"的危害,研究开发环保可降解渔用材料已成为我国现代渔业可持续发展的重大问题之一。以可生物降解树脂聚乳酸(PLA)制成的刺网为研究对象,研究了PLA单丝的物理性能,并于2019年9月至10月在琅琊岛渔场通过捕捞实验,对比分析了PLA刺网和常规聚酰胺(PA)刺网的物理性能和捕捞效率。结果显示,可生物降解的PLA刺网对于梭子蟹(Portunus trituberculatus)的捕获量比PA刺网少75.0%, PLA刺网对于鲐鱼(Pneumatophorus japonicus)的捕获量比PA刺网多90.0%。PLA刺网的捕捞总量略低于PA刺网,PA刺网的捕捞效率比PLA刺网高约60.0%。PLA和PA刺网捕捞实验前后的拉伸力学性能结果表明,这两种刺网的网目断裂强力均明显降低。此外,与传统PA刺网相比,PLA网目破损程度更高,这是由于PLA单丝的韧性较差,缺少弹性以及柔性,断裂强度明显低于PA单丝,因此PLA刺网网目更容易断裂。显微镜照片显示,PA刺网一般从网目中间破损,而PLA刺网破损情况多发生在结节处。尽管PLA刺网捕捞效率不如PA刺网,但其在减少海上"幽灵捕捞"和塑料污染方面具有潜在优势。     

核壳结构nano-CaCO_3/POE复配体系改性渔用聚乙烯复合材料的制备及性能

以纳米碳酸钙/乙烯辛烯共聚物(nano-CaCO_3/POE)复配体系为改性剂,采用两种共混工艺,调节nano-CaCO_3/POE复配体系在渔用高密度聚乙烯(HDPE)基体中的含量,制备了核壳结构nano-CaCO_3/POE复配体系改性渔用聚乙烯三元复合材料(nano-CaCO_3/POE/HDPE),研究了共混工艺、复配体系配比及其含量对nano-CaCO_3/POE/HDPE三元纳米复合材料微观形态结构和宏观力学性能的影响。结果表明,当复配体系中nano-CaCO_3和POE质量比为1∶4时,两步法共混工艺可使nano-CaCO_3与POE在聚乙烯基体中形成nanoCaCO_3为核、POE为壳的核壳结构,且该核壳结构由POE包裹2~3颗nano-CaCO_3粒子组成,尺寸为100~200 nm,均匀分散于聚乙烯基体中。此外,当核壳结构nano-CaCO_3/POE复配体系的含量为5%时,所制备的nano-CaCO_3/POE/HDPE三元复合材料的综合力学性能最优,与纯HDPE相比,其断裂强度、屈服强度和断裂伸长率分别提高了37.2%、5.1%和27.0%。     

聚酮单丝材料的渔用适配性

聚酮(POK)材料是由一氧化碳、烯烃(乙烯、丙烯)共聚合成的一种工程塑料,有着良好的拉伸性能和优异的抗冲击性能,有望成为一种渔用新材料。为了探究聚酮单丝材料的渔用适配性,本文对POK单丝进行了热性能和动态力学性能测试,又测试分析了其蠕变性能、力学性能和耐磨性能。结果表明：POK单丝的结晶度为38.44%、熔融温度为200.8℃,且使用环境温度可达150℃;与相同直径的超高分子量聚乙烯(UHMWPE)单丝和聚酰胺(PA)单丝相比,同等温度下POK单丝的模量最大(118.04 MPa),且在低温下(0-20°C)具有更优异的力学模量;蠕变试验测得POK单丝的拉伸应变在9%左右,在绳网的长效应用上POK单丝优势明显高于UHMWPE单丝和PA单丝;在结节状态下,POK单丝的结节强力在干(3.96 daN)、湿(4.02 daN)状态下均高于同等直径的UHMWPE单丝和PA单丝;另外,POK单丝的耐磨性能表现优异,在相同摩擦条件下,干(湿)态下POK单丝的强力保持率达58.38%(60.90%),也高于同等直径的UHWMPE单丝和PA单丝。研究表明,与相同直径的UHMWPE单丝和PA单丝相比,POK单丝耐磨、耐高温、高模量、低蠕变、高结节强力,其综合性能和适配性好,这为渔用POK单丝绳索网具的开发及其产业化应用提供了理论和技术支撑。     

拉伸工艺对渔用聚乙烯纤维结构与性能的影响

为纺制高性能渔用聚乙烯纤维,作者以齐鲁石化生产的高密度聚乙烯为原料,进行螺杆挤出机熔融纺丝-多级热拉伸纺丝实验。研究表明,二级拉伸工艺可使聚乙烯大分子链在纤维中的排列更加规整;提高大分子链的取向度,制备的渔用聚乙烯纤维的综合渔用性能更好。随着总拉伸倍数的提高,聚乙烯纤维的断裂强度、声速取向和热性能均显著提高。随拉伸倍数提高,渔用聚乙烯纤维的结节强度却呈现先升高后降低的趋势。结果显示,一级拉伸倍数为8.17倍时,聚乙烯纤维的断裂强度和结节强度分别为5.71cN/dtex和4.56cN/dtex;当采用二级拉伸工艺,一级拉伸倍数8.17倍,总拉伸倍数为9.52倍时,所制备的渔用聚乙烯纤维的断裂强度和结节强度分别为7.91cN/dtex和5.24cN/dtex,比现行国家标准中规定的聚乙烯单丝优等品指标高出41.3%和34.4%。     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.     

Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide

Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.     

An overview of stress physiology of fish transport: changes in water quality as a function of transport duration

This study brings an integrated analysis about the relationship between water deterioration and its physiological consequences in live fish transport. The analysis was focused on the transport water and its deterioration, and physiological challenges imposed on the fish. Usual commercial handling procedures employed to mitigate fish stress during transport were discussed. Future topics of research for the establishment of safer fish transport protocols were proposed. Transport was classified into short (≤8 h) or long transport (>8 h). The main issue in short transports should be the prevention of water pH reduction, while in long transports it is the increase in ammonia. Plasma cortisol is the most employed marker for stress and is acutely elevated upon short episodes of transport, but remains elevated even in long‐transport events. Plasma glucose is perhaps a better marker for handling stress. Plasma lactate, pH, osmolality CO₂ and ions should be more often evaluated. Plasma Na⁺ and Cl^‐ are very useful markers of acidosis, due to their respective exchange for H⁺ and , for acid–base regulation. The establishment of species‐specific transport protocols should be preceded by such combined analyses of water and physiological parameters.     

Are hatchery‐reared abalone naïve of predators? Comparing the behaviours of wild and hatchery‐reared northern abalone,Haliotis kamtschatkana (Jonas, 1845)

Abalone populations have declined worldwide, generating interest in enhancement using hatchery‐reared individuals. In many cases, such restoration efforts have met with limited success due to high predator‐induced mortality rates. Furthermore, the mortality rates of outplanted hatchery abalone are often considerably higher than for wild individuals. This study uses northern abalone (Haliotis kamtschatkana) as a case study to determine whether hatchery‐reared abalone behave differently than their wild counterparts. In the field, outplanted hatchery‐reared abalone were significantly less responsive than wild abalone, in terms of number of abalone responding and intensity of response, to nearby movement and to physical contact with an inert probe. Also, when encountering a cue to which all abalone responded (a seastar predator), hatchery‐reared individuals remained subdued. Anti‐predator behavioural deficits in hatchery‐reared abalone were more pronounced in 4‐year‐old individuals than in 1‐year‐old individuals, suggesting an influence of either age or amount of time spent in the hatchery environment. These behavioural differences are expected to increase the vulnerability of hatchery‐reared abalone to predators, and are likely a major cause of their elevated predator‐induced mortality when outplanted.     

Effects of cadmium on the kinetics of calcium uptake in developing tilapia larvae, Oreochromis mossambicus

The toxic effects of Cd²⁺ on Ca²⁺ influx kinetics in developing tilapia (Oreochromis mossambicus) larvae were evaluated. Addition of 20 µg l^-1 of Cd²⁺ to the environment of 0 and 3 day-old larvae competitively inhibited the Ca²⁺ uptake within 4h resulting in a great increase in K_m values for Ca²⁺ influx (19.3 and 17.4 fold, respectively) as compared with their respective controls. Consequently, the actual Ca²⁺ influx of larvae in solutions of 0.2 mM Ca²⁺ are suppressed by 32–45%. Also, 3 day-old larvae were more sensitive to internally accumulated Cd²⁺ than 0 day-old larvae. Although the Ca²⁺ influx in 0 and 3 day-old larvae may be restored to the levels of their respective controls with 24h of being transferred to a 20 µg l^-1 Cd²⁺ solution, total body Ca²⁺ content was significantly reduced in 3 day-old larvae. Increased Ca²⁺ uptake efficiency ensures sufficient Ca²⁺ for normal growth. However, rapid increase in Ca²⁺ influx after hatching also leads to higher Cd²⁺ uptake. Exposure to Cd²⁺ will lead to a drop in body Ca²⁺ content resulting in retardation of larval growth. Therefore, we conclude that if Ca²⁺ uptake is interfered with at this critical stage of development, larvae will not be able to maintain normal levels of body Ca²⁺ and will show signs of Cd²⁺ poisoning.     

Migratory dynamics of stream-spawning longnose gar (Lepisosteus osseus)

Abstract– Literature evidence suggests that lake-dwelling longnose gar (Lepisosteus osseus) enter tributary streams to spawn, Until the present study, the dynamics of this breeding migration had never been investigated quantitatively. During the summers of 1991 and 1992, longnose gar were captured as they entered Weaubleau Creek, Missouri, a tributary of Harry S. Truman Reservoir. The in-stream spawning migration began in early April and ended in late May, and was positively correlated with stream flow and water level, and negatively correlated with water temperature. In-stream residence times ranged from 15 to 94 days, with males exhibiting longer residence times than females. Once in-stream, longnose gar travelled as far as 10 km upstream and occupied certain pools at greater relative frequencies. Although the reason for this preferential utilization is not completely understood, it may relate to pool depth and riffle proximity. Longnose gar disperse from the spawning stream great distances, with gar captured in Weaubleau Creek being recaptured up to 48 km away. This information should provide fisheries biologists the means to consider the reproductive ecology of this species in their conservation and management decisions.     

Nutritional regulation of hepatocyte fatty acid desaturation and polyunsaturated fatty acid composition in zebrafish (Danio rerio) and tilapia (Oreochromis niloticus)

The desaturation and elongation of [1-¹⁴C]18:3n-3 was investigated in hepatocytes of the tropical warm freshwater species, zebrafish (Danio rerio) and Nile tilapia (Oreochromis niloticus). The hepatocyte fatty acid desaturation/elongation pathway was assayed before and after the fish were fed two experimental diets, a control diet containing fish oil (FO) and a diet containing vegetable oil (VO; a blend of olive, linseed and high oleic acid sunflower oils) for 10 weeks. The VO diet was formulated to provide 1% each of 18:2n-6 and 18:3n-3, and so satisfy the possible EFA requirements of zebrafish and tilapia. At the end of the dietary trial, the lipid and fatty acid composition was determined in whole zebrafish, and liver, white muscle and brain of tilapia. Both zebrafish and tilapia expressed a hepatocyte fatty acid desaturation/elongation pattern consistent with them being freshwater and planktonivorous fish. The data also showed that hepatic fatty acid desaturation/elongation was nutritionally regulated with the activities being higher in fish fed the VO diet compared to fish fed the FO diet. In zebrafish, the main effect of the VO diet was increased fatty acid Δ6 desaturase activity resulting in the production of significantly more 18:4n-3 compared to fish fed the FO diet. In tilapia, all activities in the pathway were greater in fish fed the VO diet resulting in increased amounts of all fatty acids in the pathway, but primarily eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). However, the fatty acid compositional data indicated that despite increased activity, desaturation of 18:3n-3 was insufficient to maintain tissue proportions of EPA and DHA in fish fed the VO diet at the same level as in fish fed the FO diet. Practically, these results indicate that manipulation of tilapia diets in commercial culture in response to the declining global fish oil market would have important consequences for fish fatty acid composition and the health of consumers. Scientifically, zebrafish and tilapia, both the subject of active genome mapping projects, could be useful models for studies of lipid and fatty acid metabolism at a molecular biological and genetic level. This revised version was published online in August 2006 with corrections to the Cover Date.