Serotonin stimulates ovarian maturation and spawning in the black tiger shrimp Penaeus monodon

Serotonin (5-hydroxytryptamine, 5HT) has been reported to induce ovarian maturation and spawning in the crayfish Procambarus clarkii and white Pacific shrimp Litopenaeus vannamei. The aim of this study was to explore the role of exogenous 5HT on the reproductive performance of the black tiger shrimp Penaeus monodon. 5HT solution was injected into domesticated P. monodon broodstock at 50 μg/g body weight and ovarian maturation and spawning were recorded. The presence of 5HT in the ovary and oviduct of P. monodon was also studied by immunohistochemistry and its levels in the ovary by enzyme link immunoabsorbance assay (ELISA). The 5HT-injected P. monodon developed ovarian maturation and spawning rate at the level comparable to that of unilateral eyestalk-ablated shrimp. Hatching rate and the amount of nauplii produced per spawner were also significantly higher in the 5HT-injected shrimp, compared to the eyestalk-ablated shrimp. 5HT-positive reactions were found in the follicular cells of pre-vitellogenic oocytes, in the cytoplasm of early vitellogenic oocytes and on the cell membrane and cytoplasm of late vitellogenic oocytes. 5HT in the ovary was present at 3.53 ± 0.26 ng/mg protein level in previtellogenic stage and increased to 17.03 ± 0.57 ng/mg protein level in the mature stage of the ovary. The results suggest a significant role of 5HT, possibly directly on the ovary and oviduct, on the reproductive function of female P. monodon.     

副溶血弧菌对斑节对虾非特异性免疫酶活性的影响

为了研究副溶血弧菌对斑节对虾非特异性免疫酶活性的影响,分别对斑节对虾注射生理盐水和副溶血弧菌,于不同时间点测定肝胰腺和鳃中的总抗氧化能力(T-AOC)、酸性磷酸酶(ACP)、碱性磷酸酶(ALP)和溶菌酶(LSZ)的活性变化。结果显示,与对照组相比,感染副溶血弧菌后,肝胰腺和鳃中T-AOC活性分别于12和6 h达到最大值(P0.05),随后逐渐降低;肝胰腺中ACP活性于3 h显著升高,随后逐渐降低,并于24 h达到最小值(P0.05),而鳃中ACP活性于12 h达到最大值,随后逐渐降低,并于48 h显著低于对照组(P0.05);肝胰腺和鳃中ALP活性整体均呈现出先升高后下降的趋势,但未出现显著低于对照组的现象;肝胰腺和鳃中LSZ活性均于3 h显著升高至最大值(P0.05),随后逐渐恢复至初始水平。研究表明,副溶血弧菌感染对斑节对虾非特异性免疫酶活有显著影响,对其机体免疫防御系统有明显的破坏作用。     

The effects of density and artificial substrate on intensive shrimp Litopenaeus vannamei nursery production

Recirculating aquaculture systems (RAS) can be installed indoors, allowing year-round production of tropical animals in nearly any climate. A nursery phase is commonly used in Litopenaeus vannamei production since it allows for enhanced biosecurity and better quantification of animals while reducing space requirements. However, it is unclear whether animal density and inclusion of artificial substrate may improve shrimp performance during the nursery phase. In this experiment, we compared shrimp production parameters in two stocking densities with or without the use of an artificial substrate by creating four treatments: low-density LD; 1500 PL/m⁻³, low-density with substrate LDS, high-density HD; 3000 PL/m⁻³), and high-density with substrate (HDS). The LDS and HDS treatments included 0.46-m² of high-density polyethylene 2.5-cm mesh as a substrate, which increased the tank surface area by 21 %. Each treatment was randomly assigned to four 160-l culture tanks, each with a biofilter. The shrimp had an initial weight of 4 mg and were grown for 50 days. The low-density treatments had significantly higher dissolved oxygen (DO) and pH than the high-density treatments (P ≤ 0.001). Specifically, LDS had the highest DO and pH followed by the LD, HD, and HDS treatments, respectively. High-density treatments had significantly higher NO₂-N levels than low-density treatments during week 2 of the experiment when an unusually high concentration of nitrite was observed. FCR was significantly lower in both low-density treatments than in high-density treatments. At harvest, the total biomass (kg m⁻³) was significantly higher in high-density treatments than in low-density treatments (P ≤ 0.001), and the HDS treatment had a significantly greater biomass output than HD. Producers should consider artificial substrate and higher densities during nursery production to maximize shrimp production; however, the effects on water quality should also be taken into account.     

长毛对虾海水养殖环境以及虾肠道微生物群落结构研究

为了研究长毛对虾养殖环境以及对虾肠道微生物种群结构的特征,实验分别采集养殖区进水口水体、养殖池底泥、养殖池水体以及长毛对虾肠道样品,采用构建16S rRNA基因克隆文库的方法对不同样品间的微生物群落组成进行了研究。结果表明,4组样品中共获得621条序列,操作分类单元(OTU)总数达212个,表明养殖环境微生物群落结构具有高度的多样性。从遗传进化树分析发现,进水口水体中细菌优势种群为蓝细菌(53.97%)、α-变形杆菌(13.76%)和γ-变形杆菌(10.58%);养殖池水体细菌优势种群为蓝细菌(33.55%)、γ-变形杆菌(14.84%)、厚壁菌(14.19%)、拟杆菌(12.26%)和α-变形杆菌(9.68%);养殖池底泥细菌优势种群大部分属于厚壁细菌(79.12%);对虾肠道细菌优势种群为厚壁细菌(75.79%)、梭杆菌(13.68%)和γ-变形杆菌(10.53%)。在目分类水平上,养殖池底泥、养殖池水体和对虾肠道中芽孢杆菌占有较高的比例,分别占克隆数的69.78%、13.55%和72.63%;进水口水体和养殖池水体中红细菌的比例较高,分别占克隆数的10.05%和9.68%。本研究分析了养殖环境以及对虾肠道微生物的群落结构,揭示微生物从水源到对虾肠道内的演替规律。总体上,本养殖系统微生物群落结构良好,但在养殖池水体和对虾肠道中也检测到黄杆菌类群和少量的弧菌。本研究有助于了解养殖环境对于对虾肠道微生物组成的影响,并为长毛对虾病害的预防提供参考。     

Biochemical characterization and physiological role of cortical rods in black tiger shrimp, Penaeus monodon

Cortical rods (CRs), precursors of egg jelly investment in many penaeoid shrimp, are composed of different proportions of proteins and carbohydrates, the physiological role of which still requires extensive investigation. In this study, we demonstrated the biochemical properties of the CRs and their role in the induction of the acrosome reaction (AR). Profiles of the isolated CRs revealed a number of major protein bands ranging from 35 to 230 kDa. These CR proteins were extensively glycosylated and sulfated. Lectin-based carbohydrate analysis further revealed the highest reactivity of concanavalin A (Con A) among other lectins used. In addition, the selective interference of Con A binding with mannose but not glucose indicated that CR glycoproteins were of high-mannose type. Using immunoblotting with anti-CR antibody, we further demonstrated that part of egg water (EW, a natural AR inducer) was derived from miscible components of the CRs. Physiological tests of water-soluble CR (wsCR) revealed its high AR inducing competency comparable to that of EW, which was far superior to that of acid-urea treated CR (auCR). Furthermore, the wsCR-induced AR was selectively inhibited by Con A, suggesting the significance of the exposing mannose residues in regulating P. monodon sperm AR response.     

Structure and function of antimicrobial peptide penaeidin-5 from the black tiger shrimp Penaeus monodon

The gene for penaeidin-5, an antimicrobial peptide comprising 55 amino acids, was isolated from the hemocyte of black tiger shrimp (Penaeus monodon). RT-PCR expression tests revealed that penaeidin-5 was produced in hemocytes, gills, the intestine and muscle. Western blot analysis confirmed the panaeidin-5 was aboundantin hemocytes, the intestine and hemolymph. Immunohistochemistry revealedpenaeidin-5 in the cuticle and gills that are considered primary defense barriers. The deduced amino acid sequence of penaeidin-5 included a proline-rich N-terminal domain and a carboxyl-domain that contained six cysteine residues. Circular dichrosim analysis revealed an -helix in its secondary structure and the predicted 3D structure indicated two-disulfide bridges in the -helix. Based on the sequence of penaeidin-5 peptide cDNA, synthetic penaeidin-5 was prepared to carry out functional tests. The synthetic peptide had efficient bacteriostatic and bactericidal activity against Aerococcus viridans, and also inhibited the growth of two filamentous fungi, Fusarium pisi and Fusarium oxysporum. To measure penaeidin-5 in vivo, black tiger shrimp were challenged with Vibrio alginolyticus and A. viridans. At 3 h post-challenge, penaeidin-5 was induced and bacterial numbers decreased significantly by 12 h and 24 h.     

Comparison of dot blot and PCR diagnostic techniques for detection of white spot syndrome virus in different tissues of Penaeus monodon

Comparison of PCR and dot blot diagnostic techniques for detection of white spot syndrome virus (WSSV) was made on different tissues of infected Penaeus monodon including eye stalk, eye stalk with eye, gills, cuticle, pleopod, periopods, uropods and telson. Dot blots of crude DNA extracted from infected tissue samples showed positive reactions with all the samples; however, the sensitivity of the dot blot was reduced with the purification of DNA samples extracted from pleopod, telson and uropod. PCR was found to be more sensitive when compared to dot blot. Both crude DNA and purified DNA samples extracted from all the tissues except for eye stalk with eye showed single step nested PCR positive reaction. The amplification of all or either of the three bands of 941 bp, 525 bp and 204 bp size varied with the tissues analysed. The severity of infection assessed by PCR amplification was found to be maximum in cuticle and telson followed by gill. Other tissues such as eye stalk, pleopod, periopods and uropod were observed to have mild infection. The maximum intensity of the PCR product was for the smallest amplified product of 204 bp followed by 525 bp and the weakest intensity was observed for the 941 bp size. The limitation of PCR due to inhibiting factors present in tissues could be overcome with the use of dot blot which gave positive reaction from the DNA extracted from eye stalk including the eye but yielded no amplification by PCR.     

The effects of ozone and probiotics on the survival of black tiger shrimp (Penaeus monodon)

Total ozone production (TOP) from an ozonator, residual ozone concentration (ROC) in water, and the effects of ozone with or without probiotic supplemented feeds on bacterial growth, and shrimp (Penaeus monodon) survival were investigated. Minimal effective ROC to inhibit 3 log units of Vibrio harveyi D331 for 6 h and 2 log units of Bacillus S11 for 9 h was 0.38 g O₃/l of ROC from 5-min ozonation. Shrimp postlarvae exposed to 0.34–0.50 mg O₃/l ROC (8-h ozonation) caused loss of balance, immobility and destruction of gill lamellar epithelium. In vivo treatment of juvenile P. monodon reared on probiotic feed for 1 month revealed that 0.35 mg O₃/l ROC (30-min ozonation) effectively inhibited 3 log units of V. harveyi D331 for 24 h. At this ROC dosage, there was no effect either on shrimp or on intestinal probiotics (Bacillus S11). Shrimp survival from probiotic treatment, coupling with ozonation, increased significantly (P≤0.05) compared with controls.     

The impact of tiger shrimp, Penaeus monodon Fabricius, postlarvae stocking density on production in traditional tambak systems in East Java, Indonesia

The effects of stocking density [range: 2.0-5.5 postlarvae (PL) m^?2] and water quality on the production of a traditional tambak tiger shrimp, Penaeus monodon Fabricius, culture system on one farm in Probolinggo, East Java, were studied during one culture period of 126 days using eight ponds. Production characteristics were recorded and water quality parameters monitored. Production was quadratically influenced by stocking density. The optimum density was 4.8 PL m^?2, which corresponds with a production per crop of around 300 kg ha^?1. Production was also quadratically related to mean shrimp body weight at harvest, while there was an inverse relationship between production and bottom organic matter, indicating that shrimp biomass diminishes the amount of organic matter accumulating at bottom of the tambak.     

养殖密度对流水养殖系统中俄罗斯鲟幼鱼生长的影响

为研究流水养殖系统中不同养殖密度对俄罗斯鲟幼鱼生长的影响,实验将初始体质量为(29.70±1.32)g的俄罗斯鲟幼鱼分置于2.5(SD1)、3.6(SD2)和4.7 kg/m3(SD3)3个养殖密度进行流水池塘(4.4 m×4.4 m×0.45 m)养殖,每个密度设3个重复,实验周期为90 d。结果显示:低密度组(SD1)幼鱼增重率(WG)、体长增长率(LG)、特定生长率(SGR)和饵料转化率(FCR)分别为362.01%±15.87%、55.88%±4.77%、(1.79±0.03)%d、114.95%±4.52%,显著高于高密度组(SD3)的272.30%±2.74%、46.34%±6.22%、(1.53±0.02)%/d、94.49%±1.96%,而SD3组幼鱼生长离散程度和死亡率显著高于SD1组幼鱼;随养殖密度增加,幼鱼体内蛋白和脂肪含量降低,水分和灰分含量升高,但是不存在显著性差异。研究表明,较高的养殖密度对俄罗斯鲟幼鱼的生长造成了显著的负面影响。     

Use of artificial hides to increase the stocking density and production of estuary grouper, Epinephelus salmoides Maxwell,reared in floating net cages

The relative growth and production of estuary grouper, Epinephelus salmoides, in response to seven combinations of hiding space and stocking density were studied in floating net cages. Used car tyres were suspended in the net cages to provide hiding space for the fish. The seven combinations of hiding space and stocking density were as follows:

Provision of hiding space in the net cages was found to permit an increase in the stocking density from the optimal rate of 60 fish/m³ (without artificial hides) to 156 fish/m³. The net production was found to increase from 8.5 kg/m³ to 19.5 kg/m³ after 3 months. Growth in terms of weight gain per fish, survival rate and food conversion ratio at stocking rates below 156 fish/m³ with hiding space between 116 and 222 cm³/fish was comparable to that observed at the optimal stocking density without hiding space (60 fish/m³). The growth of fish stocked at 180–204 fish/m³ with hiding space of 272–289 cm³/fish, respectively, was found to be significantly depressed. Thus, with the provision of hiding space of 251 cm³/fish, the stocking density could be increased to as high as 156 fish/m³ and the production of fish could be increased by 230% over that at the usual optimal stocking rate of 60 fish/m³ without artificial hides.     

The existence of gonadotropin-releasing hormone (GnRH) immunoreactivity in the ovary and the effects of GnRHs on the ovarian maturation in the black tiger shrimp Penaeus monodon

Immunocytochemical localization using antibodies against five isoforms of gonadotropin-releasing hormone (GnRH), namely, luteinizing hormone-releasing hormone (LHRH), salmon (s)GnRH, octopus (oct)GnRH, lamprey (l)GnRH-I, and lGnRH-III, showed that only lGnRH-I immunoreactivity (ir-lGnRH-I) was localized in follicular cells of proliferative, vitellogenic, and mature ovaries. The effects of exogenous GnRHs on the ovarian maturation cycle of Penaeus monodon were compared by treating female broodstocks with LHRH, sGnRH, and lGnRH-I. The cycle of ovarian maturation in both eyestalk-ablated and eyestalk-intact shrimp administered with the three isoforms of GnRH was significantly shorter than that of the control animals. Moreover, administrations of all GnRH isoforms showed similar numbers of spawned eggs and the percentage of successful fertilization as in the control animals. These findings suggest that GnRHs may be highly conserved peptides that play an important role in inducing the ovarian maturation in the shrimp.     

The influence of stocking density, light and temperature on the growth, production and nutrient removal capacity of Porphyra dioica (Bangiales, Rhodophyta)

The optimal conditions for growth of Porphyra dioica gametophytes were investigated in the laboratory, focusing on bioremediation potential. Porphyra dioica is one of the most common Porphyra species along the northern coast of Portugal and can be found year-round. The influence of stocking density and photon flux density (PFD) on the growth, production and nutrient removal was tested. Maximum growth rates, up to 33% per day, were recorded with 0.1 g fw l^− 1 at 150 and 250 μmol photons m^− 2 s^− 1. Growth rate decreased significantly with increasing stocking density. Productivity (g fw week^− 1) had an inverse trend, with more production at the higher stocking densities. At 150 μmol m^− 2 s^− 1 and with 1.5 g fw l^− 1, 1.4 g fw week^− 1 were produced. At this PFD, there was no significant difference in production between 0.6 to 1.5 g fw l^− 1. Nitrogen (N) content of the seaweeds decreased with increasing stocking densities and PFDs. The maximum N removal was recorded at 150 μmol m^− 2 s^− 1, with 1.5 g fw l^− 1 stocking density (1.67 mg N day^− 1). However, the N removed by thalli at 50 μmol photons m^− 2 s^− 1 was statistically equal to that at 150 and 250 μmol photons m^− 2 s^− 1, at a stocking density of 1.0 g fw l^− 1. The influence of temperature and photoperiod on growth and reproduction was also assessed. Growth rates of P. dioica were significantly affected by temperature and photoperiod. In this experiment (with 0.3 g fw l^− 1 stocking density), the highest growth rate, 27.5% fw day^− 1, was recorded at 15 °C and 16 : 8¯, L : D¯. Male thalli started to release spermatia 21 days after the beginning of the experiment, in temperatures from 10 to 20 °C and with 10, 12 and 16 h of day length. Unfertilized female-like thalli were observed at 10 to 20 °C, under all photoperiods tested. Growth of these thalli declined after 4 weeks. By then, formation of young bladelets in the basal portion of these thalli was observed. After 7 weeks all biomass produced was solely due to these vegetatively propagated young thalli, growing 22.4% to 26.1% day^− 1. The results of this study showed that P. dioica appears to be a candidate as a nutrient scrubber in integrated aquaculture systems.     

两种形态变异类型日本囊对虾稚虾高温耐受性的比较

高温耐受值(CTMax)为评估日本囊对虾稚虾高温耐受性的重要指标,本实验探讨了不同暂养温度(24、28和32℃)和升温速率[(1±0.2)℃/h和(1±0.2)℃/min]对CTMax值的影响,同时利用CTMax和环境响应系数ARR比较了两种形态变异类型日本囊对虾稚虾的高温耐受性差异,并从二者的地理分布、耗氧率、窒息点和温度系数Q10生理代谢指标对其高温耐受机理进行了分析。实验结果如下:(1)不同的暂养温度和升温速率对两种形态变异类型日本囊对虾稚虾的CTMax值均有显著影响(P0.05);(2)在相同升温速率下,32℃组形态变异类型Ⅱ稚虾的CTMax值高于形态变异类型Ⅰ(P0.05),各实验温度范围内形态变异类型Ⅱ稚虾的ARR值都显著大于形态变异类型Ⅰ(P0.05);(3)各温度组中形态变异类型Ⅰ稚虾的耗氧率和窒息点均高于形态变异类型Ⅱ(P0.05);(4)形态变异类型Ⅰ稚虾在24~28℃的Q10值小于28~32℃的Q10值,而形态变异类型Ⅱ稚虾则与此相反,二者的适温范围不同。结果表明,不同温度对日本囊对虾稚虾的CTMax值、耗氧率和窒息点均有影响,主要分布于南海水域的形态变异类型Ⅱ稚虾的高温耐受性强于主要分布于东海和南海北部的形态变异类型Ⅰ稚虾。     

Effects of stocking density on mortality,growth and physiology of juvenile Amur sturgeon (Acipenser schrenckii)

To evaluate effects of stocking density on welfare of Amur sturgeon (Acipenser schrenckii), an experiment was designed using three initial stocking densities in flow‐through tanks (LSD = 3.7 kg m^?3, MSD = 6.9 kg m^?3, and HSD = 9.3 kg m^?3, respectively) for 60 days. Growth, body composition, and haematological and biochemical parameters were monitored. The mortality and feed conversion rate (FCR) were not affected by stocking density. However, the specific growth rate (SGR), final weight and weight gain in the HSD group were significantly lower than in the LSD and MSD groups. The hepatosomatic (HSI) and viscerosomatic indices (VSI) varied inversely with regard to stocking density. Stocking density did not affect crude protein levels in fish. In contrast, the total lipid level was significantly higher in the LSD group compared to the MSD and HSD groups. The levels of erythrocytes and haemoglobin were positively correlated with stocking density. Serum total bilirubin and urea in HSD group were significantly higher than in the LSD group while serum triglycerides showed opposite tendencies. Differences between treatments were not registered for glucose, total protein and albumin. In conclusion, higher stocking density resulted in increased immunosuppression and enhanced energy mobilization. The latter was necessary to enable Amur sturgeon to cope with crowding.     

密度胁迫对凡纳滨对虾稚虾免疫指标及生长的影响

将体长为（3.59±0.26）cm的凡纳滨对虾（Litopenaeus vannamei）按1 800尾.m-3、1 500尾.m-3和1 200尾.m-3的密度分别饲养在注水0.3 m3的圆形玻璃纤维桶（容量为0.5 m3）中30 d,检测了基本水质因子、对虾肝胰腺和肌肉组织中的酚氧化酶（PO）活力、超氧化物歧化酶（SOD）活力、抗菌活力（Ua）、碱性磷酸酶（AKP）活力、体质量增长和成活率,研究了不同放养密度对凡纳滨对虾稚虾免疫指标及生长的影响。统计分析发现,试验过程中水体理化因子均在适宜范围,各处理间水质因子的差异不显著;对虾的PO活力、Ua和AKP活力均随着密度的增加而降低,SOD活力则反之;对虾的体质量增长、体质量特定增长率和成活率随着密度的增加而降低,成活率差异显著（P〈0.05）。结果表明,凡纳滨对虾（体长〈4.8 cm或体质量〈1.2 g）在密度为1 200～1 800尾.m-3时,密度胁迫可明显影响其免疫指标和生长。     

The effect of stocking density of Chinese mitten crab Eriocheir sinensis on rice and crab seed yields in rice-crab culture systems

Normally Chinese mitten crab Eriocheir sinensis were cultured for 2 years, 1 year is cultured from crab larvae to seeds or button sized crab in ponds, tanks or rice fields, the another year is cultured from seeds to market size in ponds, reservoirs or other waters. The present study was conducted to determine the effect of stocking density (0, 3.75, 15, 30 and 60 inds. per m², respectively) of Chinese mitten crab larvae on rice and crab seed yields in rice-crab culture systems using land-based enclosures (4 m × 7 m, with three replicates for each stocking density) at the Panjin Guanghe Fisheries Co. Ltd, in the Liaohe Delta, China. Zoobenthos biomass, production of crab and rice paddy, and economical profit among the treatments were determined. The experiment showed that zoobenthos biomass in rice-crab culture systems was relatively variant and not significantly correlated to these stocking density. The biomass of aquatic plant declined significantly with increasing stocking density. Specific growth rates (SGR) and survival rates of the crab were significantly higher at the lower stocking density (P < 0.05); in addition, the ratio of precocious crab and total crab significantly increased with the stocking density increasing (P < 0.05); There were not significant effect of presence of crab on yields of rice straw and rice paddy (P > 0.05). Net crab yield and net profit were the highest at the 15 treatment (P < 0.05), however, the net profits among 3.75, 15 and 30 treatments did not show significant difference (P > 0.05) economically. Based on the observations above, a stocking density of 3.75 to 30 inds. per m² was considered reasonable in rice-crab culture system.     

水温和养殖密度对大鳞鲃幼鱼的生长影响

分别进行水温和密度对大鳞鲃(Barbus capito)幼鱼的生长影响实验,旨在探索大鳞鲃适宜的放养密度和生长温度。水温实验设计为6个梯度值15℃、18℃、21℃、24℃、27℃、30℃,幼鱼初始体重为9~12 g,投喂75 d后,结果得出:在水温15~27℃时,随着温度的升高,终末体重会逐渐增加,27℃时最大值为(44.47±9.54)g,水温达到30℃时,终末体重开始下降。24℃、27℃和30℃组体重增长无显著差异,但温度达到30℃时,体重变异系数最大,为(29.82±11.36)%。密度实验设计为4个梯度值20 ind/m3、15 ind/m3、10 ind/m3、5 ind/m3,幼鱼初始体重为0.6~0.7 g,投喂60 d后,结果得出:随着放养密度的下降,体重增长的速度越快。体重、特定增长率、日增重变化在密度为5 ind/m3时最高,密度10 ind/m3与15 ind/m3没有显著差异,达到20 ind/m3时会显著下降。综合考虑,大鳞鲃适宜的养殖温度在24~27℃,静水池塘的放养密度建议在15 ind/m3左右。     

The effects of sediment redox potential and stocking density on Pacific white shrimp Litopenaeus vannamei production performance and white spot syndrome virus resistance

Redox potential represents the intensity of anaerobic condition in the pond sediment, which may affect the dominant microbial transformations of substances, the toxins production, mineral solubility, as well as the water quality in the sediment–water interface inhabited by the shrimp. This study evaluates the effect of sediment redox potential in conjunction with stocking density on shrimp production performance, immune response and resistance against white spot syndrome virus (WSSV) infection. A completely randomized two factors experimental design was applied with three different sediment redox potential, i.e. ?65, ?108 and ?06 mV, and two shrimp densities, i.e. low (60 shrimp m^?2) and high (120 shrimp m^?2). Shrimp juveniles with an initial mean body weight of 5.32 ± 0.22 g were maintained in semi‐outdoor fibre tanks (270 L in capacity) for 35 days of experimental periods. At the bottom of each tank, 5‐cm deep soil substrate with different redox potential was added according to the treatments. The survival and biomass production were significantly reduced at ?206 mV sediment redox potential, regardless of stocking density. Highly negative sediment redox potential (?206 mV) and higher stocking density significantly reduced total haemocyte counts and phenoloxydase activity, and shrimp resistance to WSSV infection. We recommend to maintain the redox potential of pond sediment at a level of more than ?206 mV.