亚甲基蓝与次氯酸钠对塔胞藻胁迫作用的比较研究

试验选取养殖生产常用消毒药品亚甲基蓝和次氯酸钠作为外源物质，探讨两者对塔胞藻的毒理学影响及塔胞藻在逆境状态下的适应性变化。结果表明：次氯酸钠对塔胞藻的胁迫表现为低浓度的刺激效应，细胞生理指标变化反映出明显的氧化毒害症状；亚甲基蓝对塔胞藻的胁迫表现为明显的抑制作用，塔胞藻对亚甲基蓝的降解作用显著，细胞所受到的氧化损伤轻微。胁迫作用下叶绿素含量、叶绿素a／b值降低，SOD活力、MDA含量升高；SOD在塔胞藻的氧化抗性机制起着重要作用。     

不同pH下五溴联苯醚BDE-85对海水小球藻的毒性效应

将海水小球藻培养在不同pH(8.66、8.44、8.19、7.93)下、不同含量(0、1.52、3.04、6.08、12.16、24.32μg/g)五溴联苯醚BDE-85中，在指数生长期时测定海水小球藻的比生长速率、净光合放氧速率、暗呼吸速率、叶绿素荧光参数以及超氧化物歧化酶和过氧化氢酶活性等参数，探讨不同pH条件下海水小球藻对BDE-85致毒胁迫的生理响应。试验结果表明，低pH条件下经过中、低含量BDE-85处理的海水小球藻的比生长速率呈增加趋势，其中6.08、12.16μg/g试验组较对照组分别增长了6.33%、7.39%;6.08μg/g试验组在低pH条件下净光合放氧速率比对照组高出18.43%,而24.32μg/g试验组则比对照组低39.98%;同时过氧化氢酶和超氧化物歧化酶活性增强，表明海水小球藻的抗氧化作用增强，出现了应激活性，但高含量(24.32μg/g试验组)的BDE-85处理下增强作用不明显。综上，低pH条件可以促进海水小球藻的生长，也可以缓解中、低含量的五溴联苯醚BDE-85的毒害作用，但当BDE-85含量过高时，其缓解效果受到抑制，并且在高含量的BDE-85处理下...     

锌胁迫对海洋小球藻生长和金属硫蛋白诱导的影响

研究锌离子胁迫对海洋小球藻生长和金属硫蛋白诱导的影响,当小球藻达到对数生长期,用不同离子浓度(5、10、20、50和100μmol/L)的锌盐(氯化锌、柠檬酸锌、乙酸锌和葡萄糖酸锌)分别进行胁迫培养,通过测定小球藻的生物量和锌结合金属硫蛋白含量,考察锌胁迫对海洋小球藻的生物量、热稳定蛋白含量以及锌结合金属硫蛋白含量的影响。结果显示,当浓度分别小于5和10μmol/L时,柠檬酸锌和氯化锌对小球藻生长无显著抑制作用;而浓度为5μmol/L时,乙酸锌和葡萄糖酸锌对小球藻生长即产生显著抑制,且抑制作用皆随锌离子浓度的增加而增大。与对照组相比,4种锌盐胁迫3 d后小球藻产生的热稳定蛋白含量极显著增加,其中以锌离子浓度为50μmol/L的葡萄糖酸锌对小球藻胁迫产生的热稳定蛋白含量最高,达到34.5 mg/g(湿藻泥)。同样在此浓度的葡萄糖酸锌胁迫下,小球藻诱导产生的锌结合金属硫蛋白的含量最高。研究表明,用锌离子浓度为50μmol/L的葡萄糖酸锌对小球藻胁迫培养,诱导产生的锌结合金属硫蛋白含量达到最高。     

六价铬对普通小球藻的急性毒性效应

为探究重金属铬在水环境中的致毒机理和生态风险，本实验开展不同浓度Cr⁶⁺(0、0.1、0.75、1.5、2.25和3 mg/L)对受试生物普通小球藻(Chlorella vulgaris)的急性毒性实验，分析藻密度、叶绿素a(Chl-a)含量、多糖含量、蛋白(TP)含量、活性氧自由基(ROS)含量、丙二醛(MDA)含量、细胞膜通透性、总抗氧化(T-AOC)能力、总超氧化物歧化酶(T-SOD)活性、谷胱甘肽(GSH)含量、植物螯合肽(PCs)含量和吸附效率等指标的影响。研究结果表明在96 h内Cr⁶⁺各浓度组均会抑制藻细胞的生长，其中3 mg/L处理组抑制率最高，为57.32%,96 h-IC₅₀为2.067 mg/L。叶绿素a(Chl-a)含量和藻细胞生物量的变化呈现一致性，3 mg/L处理组最低，仅为对照组的26.60%。藻细胞胞内多糖和TP含量随着胁迫浓度的升高而降低。胁迫浓度的增加诱导了ROS含量的升高，3 mg/L浓度组ROS水平为对照组的6倍，MDA含量呈现相同趋势。此时藻细胞受到氧化损伤，细胞膜通透性显著增强...     

EDTA二钠对培养单胞藻的影响

本试验对添加不同浓度的EDTA二钠培养等鞭金藻、扁藻、绿色杷夫藻、小球藻，经过3d的培养后，得出结论：添加1-7ms／LEDTA二钠的单胞藻增量比值最高述2．24，最低比值也有1．61，对单胞藻生长有促进作用；添加8—9ms／L的单胞藻增量比值有所降低，对单胞藻生长有一定的抑制作用。     

小球藻和盐藻利用石油烃富集油脂的研究

利用单细胞分离和紫外诱变技术分别获得海水小球藻和盐生杜氏藻的生长优势株，将其分别接种于不同石油浓度的海水培养液中，利用紫外和荧光分光光度法分别测定培养液中带共轭双键的烃类化合物和芳烃的含量，利用索氏提取法测定胞内油脂含量。结果表明，石油浓度为1.5~10.0μg/ml的培养液中，小球藻和盐藻均能有效降解带共轭双键的烃类化合物，降解率分别为25.3%~35.5%和17.9%~24.0%，芳烃降解率分别为22.1%~30.2%和18.7%~26.2%;石油浓度为3.5μg/ml时，两种微藻对带共轭双键的烃类化合物和芳烃的降解效率均最大，小球藻的降解能力略好于盐藻；石油浓度为1.5μg/ml和3.5μg/ml时，两种微藻的胞内油脂含量分别占细胞干重的14.0%和25.5%，分别是对照组的1.5倍和1.2倍，浓度为3.5μg/ml时两种微藻的胞内油脂含量均最高。该研究为利用石油污染海水培养微藻使其富集油脂及今后开发微藻燃料奠定了基础。     

不同密度、饵料对缢蛏浮游幼体生长及成活率的影响

报导了不同密度、饵料对缢蛏浮游幼体阶段生长速度及成活率的影响.不同密度共设五组,每组设一个平行组,各组密度分别为3、6、9、12、15个/mL;不同饵料共设五组,每组设一个平行组,饵料各组分别为金藻、新月菱形藻、角毛藻、海水小球藻、混合藻.结果表明,在水温23～24℃,经5d培养,不同密度组各组成活率无显著差异.壳高日生长密度为3个/mL组与其他各组之间有显著差异,其他四个密度组之间无显著差异.在不同饵料组壳高日生长中,角毛藻组与其他各组之间差异极显著.新月菱形藻、海水小球藻、混合藻组与金藻组差异极显著.新月菱形藻、海水小球藻、混合藻三组之间无显著差异.日生长最快为角毛藻组24.84 μm/d,最慢为金藻组16.14μm/d.不同饵料成活率金藻组最高为57.77％,最低为海水小球藻组31.1％.     

植物生长调节剂2，4-D 对两种绿藻生长的影响

测定了植物生长调节剂2，4-D(2，4-Dichlorophenoxyacetic acid)在不同浓度作用下对两种绿藻 --蛋白核小球藻和斜生栅藻增殖和叶绿素含量的影响。结果表明，0． 25 mg/L 和0． 50 mg/L 的2，4-D 分别是 促进小球藻和栅藻生长的最佳浓度；在0． 50 mg/L 的2，4-D 作用下小球藻和栅藻的叶绿素含量最高。高浓度 的2，4-D(＞4． 0 mg/L)对两种藻类的生长有毒性作用。     

铜绿微囊藻在光限制胁迫下的超补偿生长响应

采用铜绿微囊藻为试验材料,将其经光限制(完全黑暗)胁迫处理7d,以光照强度为3000lx、光暗周期为12h∶12h的培养组为对照。然后解除光限制胁迫,在相同接种量和相同培养条件下,将处理组和对照组均置于3000lx光照条件下培养10d。试验过程中测定铜绿微囊藻的吸光度、细胞密度、叶绿素a和细胞内蛋白质含量等指标。在光限制胁迫过程中,处理组的藻液吸光度、藻细胞密度、平均相对生长率、细胞数净增长率、叶绿素a含量及藻细胞直径较对照组均显著降低,但藻细胞蛋白质含量显著高于对照组。在恢复光照10d的培养过程中,处理组的藻液吸光度、藻细胞密度、平均相对生长率、细胞数净增长率及叶绿素a含量较对照组均显著升高,而藻细胞直径和蛋白质含量与对照组差异不显著。试验结果说明铜绿微囊藻在光限制胁迫后具有明显的超补偿生长性能。     

铜绿微囊藻在光限制胁迫下的超补偿生长响应

采用铜绿微囊藻为试验材料,将其经光限制(完全黑暗)胁迫处理7d,以光照强度为3000lx、光暗周期为12h∶12h的培养组为对照。然后解除光限制胁迫,在相同接种量和相同培养条件下,将处理组和对照组均置于3000lx光照条件下培养10d。试验过程中测定铜绿微囊藻的吸光度、细胞密度、叶绿素a和细胞内蛋白质含量等指标。在光限制胁迫过程中,处理组的藻液吸光度、藻细胞密度、平均相对生长率、细胞数净增长率、叶绿素a含量及藻细胞直径较对照组均显著降低,但藻细胞蛋白质含量显著高于对照组。在恢复光照10d的培养过程中,处理组的藻液吸光度、藻细胞密度、平均相对生长率、细胞数净增长率及叶绿素a含量较对照组均显著升高,而藻细胞直径和蛋白质含量与对照组差异不显著。试验结果说明铜绿微囊藻在光限制胁迫后具有明显的超补偿生长性能。     

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.     

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.     

Production of diatom–bacteria biofilm isolated from Seriola lalandi cultures for aquaculture application

Controlled incorporation of selected microalgae and bacteria in aquaculture systems can be beneficial because they can act as microbiological control. That is why the characteristics of biofilm generated naturally in Seriola lalandi culture cages were analysed, their potential benefit to the growth of larvae was studied, and their controlled use for improving the larval viability and as a vector to improve incorporation of previously studied probiotic bacteria was tested. According to biodiversity results, these biofilms are composed of a diatom–bacteria mix showing a decrease in biodiversity in laboratory culture conditions being dominated by Navicula phyllepta and bacteria of the family Rhodobacteraceae. This can be produced on mesh substrates incorporated in bioreactors with rapid growth rate and adhesiveness. Preliminary results from the addition of substrates with this specific biofilm in larvae culture systems showed that it is consumed by the larvae without negative effects, while positive effects on the viability of larvae in combination with probiotics were observed. Considering preliminary results, the addition of these specific substrates with diatom–bacteria biofilms could be a good improvement for aquaculture systems and together with the use of probiotics can contribute to maintaining a stable and controlled system improving the viability of the larval fish culture in its early stages.