Isolation of Pediococcus homari, etiological agent of gaffkemia in lobsters,from a California estuary

Virulent Pediococcus homari, the etiological agent of gaffkemia, a disease enzootic in Atlantic lobsters (genus Homarus), was isolated from two sites in Anaheim Bay, Calif. The concentration of P. homari was in the order of 1–10 bacteria per ml of sample. This is the first known report of free-living P. homari in the Pacific; the bacterium was previously reported to exist in infected decapod Crustaceae and sediments from the Atlantic. Introduction of P. homari may have occurred through transport of infected Homarus americanus (Atlantic lobster), or by discharge of water in contact with them.     

Ammonia production and oxidation during the culture of marine prawns and lobsters in laboratory recirculation systems

Data obtained during the culture of tropical prawns Penaeus sp. and European lobsters Homarus gammarus (L.) in 20 laboratory recirculation systems over a number of years were used to obtain gross estimates of (a) the rates and diurnal patterns of ammonia excretion, (b) food utilization and wastage, and (c) nitrification rates in biological filters. Ammonia excretion in Penaeus monodon decreased with increase in animal size from 0·93 to 0·30 mg N g^?1 day^?1 at 1·6 and 27 g live weight, respectively. Large lobsters (300 g) excreted 0·3 mg N g^?1 day^?1. Peak excretion times were approximately 3, 9 and 15 h after a single morning feed for prawns and after 6 and 12 h for lobsters. Uneaten food solids amounted to 11% (lobsters) and 32% (prawns) of the daily ration and, for 4 g animals, only 69% (lobsters) and 45% (prawns) of the food nitrogen in the daily ration was converted into crustacean flesh. Nitrification rates ranged from 0·03 to 0·43 g N oxidized per m² of filter media surface per day. Some evidence for periodicity in nitrifying activity was also found and is discussed in relation to the published literature.     

Effect of temperature and salinity on virulence of Edwardsiella tarda to Japanese flounder, Paralichthys olivaceus (Temminck et Schlegel)

Experiments were designed to determine the effects of temperature and salinity on the virulence of Edwardsiella tarda to Japanese flounder, Paralichthys olivaceus. In the temperature experiment, a two‐factor design was conducted to evaluate the effects of both pathogen incubation temperature and fish cultivation temperature on pathogen virulence. E. tarda was incubated at 15, 20, 25 and 30±1°C, and the fish (mean weight: 10 g) were reared at 15, 20 and 25±1°C respectively. The fish reared at different temperatures were infected with the E. tarda incubated at different temperatures. The results of a 4‐day LD₅₀ test showed that temperature significantly affected the virulence of E. tarda (P<0.01) and the interaction between the two factors was also significant (P<0.01). For fish reared at 15°C the virulence of E. tarda was the highest at 25°C of pathogen incubation, followed by 20, 15 and 30°C. When the fish rearing temperature was raised to 20 and 25°C, the virulence of E. tarda incubated at all temperatures increased. Isolation testing demonstrated results similar to those of LD₅₀. The higher rearing temperature increased the proliferation rate of the pathogen in fish. In the salinity experiment, the incubation salinity of E. tarda was at 0, 10, 20 and 30 g L^?1, respectively, and the fish with mean weight of 50 g were cultured in natural seawater of 30 g L^?1. The results of one‐way anova in 4‐day LD₅₀ test showed that incubation salinity significantly affected virulence. Virulence was lower when the salinity of the incubation medium was at 0 and 30 g L^?1, higher at 10 and 20 g L^?1. The results of isolation test were in accordance with those of LD₅₀. At 20 g L^?1E. tarda had a faster proliferation rate than that at 10 g L^?1.     

草鱼出血病细胞培养灭活疫苗的研究——疫苗株的免疫原性及其有效免疫剂量的比较

本文比较了疫苗株FR—854和FR—836—w的免疫原性,及其对三寸左右草鱼种的有效免疫剂量。疫苗株FR—854和FR—836—w均有较强的免疫原性,其保护力可达70％以上。但试验结果初步证明,FR—854疫苗比FR—836—w疫苗免疫原性更强。经统计分析,FR—854疫苗的免疫保护力可达88.9±12.0(6)％,血清中和抗体效价为160.5±58.9(6);而FR-838-W疫苗分别只有71.3±14.2(6)％、88.3±26.2(6);二者有显著的差异(0.05>P>0.01)。注射免疫三寸左右的草鱼种,FR—854的免疫剂量在3—5×10~(4.5)TCID_(50)/尾左右,FR—836—w在3—5×10~(7.5)TCID_(50)/尾左右,其免疫保护力可达80％左右,同时我们测得ER—854的半数免疫量为10~(5.1)TCID_(50)/ml。     

草鱼出血病细胞培养灭活疫苗的研究——疫苗株的免疫原性及其有效免疫剂量的比较

本文比较了疫苗株FR—854和FR—836—w的免疫原性,及其对三寸左右草鱼种的有效免疫剂量。疫苗株FR—854和FR—836—w均有较强的免疫原性,其保护力可达70%以上。但试验结果初步证明,FR—854疫苗比FR—836—w疫苗免疫原性更强。经统计分析,FR—854疫苗的免疫保护力可达88.9±12.0（6）%,血清中和抗体效价为160.5±58.9（6）;而FR-838-W疫苗分别只有71.3±14.2（6）%、88.3±26.2（6）;二者有显著的差异（0.05>P>0.01）。注射免疫三寸左右的草鱼种,FR—854的免疫剂量在3—5×10^4.5TCID0/尾左右,FR—836—w在3—5×107.5TCID₅₀/尾左右,其免疫保护力可达80%左右,同时我们测得ER—854的半数免疫量为10^5.1TCID₅₀/ml。     

Characterization of Pseudomonas aeruginosa associated with diseased postlarval abalone in Shenzhen, China

Outbreaks of mass mortality of postlarval abalone, Haliotis diversicolor supertexta, have occurred in south China since 2002 and have forced many abalone farms to close. About 30 representative bacterial strains were isolated from a sample of five diseased postlarval abalone, taken 25 days post-fertilization during an outbreak of postlarval disease in Shenzhen, China, in October 2006. Bacterial challenge tests showed that the predominant strain, designated as strain 22, was highly virulent to postlarvae with an LD₅₀ value of 7.8 × 10⁴ colony forming units (CFU) ml⁻¹, while four of the other isolates were weakly virulent with LD₅₀ values ranging from 1 × 10⁶ to 1 × 10⁷ CFU ml⁻¹, and the remaining 25 isolates were classified as avirulent with LD₅₀ values greater than 1 × 10⁸ CFU ml⁻¹. By means of API 20NE and 16S rDNA and ITS sequencing analyses, strain 22 was identified as Pseudomonas aeruginosa. Antibiotic susceptibility tests showed that strain 22 exhibited around 75% of susceptibility to 16 various antibiotics tested. The results of this study show P. aeruginosa as one of the bacteria involved in the mortality of abalone postlarvae in Shenzhen, China.     

Supplementation of microbial levan in the diet of Cyprinus carpio fry (Linnaeus, 1758) exposed to sublethal toxicity of fipronil: effect on growth and metabolic responses

A 60-day feeding trial was conducted to study the effect of dietary microbial levan on growth performance and metabolic responses of Cyprinus carpio fry exposed to sublethal dose (1/10th LC₅₀) of fipronil [(±)-5-amino-1-(2,6-dichloro-α,α,α-trifluoro-p-tolyl)-4-trifluoromethylsulfinylpyrazole-3-carbonitrile]. Two hundred and twenty five fry were randomly distributed in five treatments in triplicates. Four purified diets were prepared with graded levels of microbial levan. Five different treatment groups were levan control L₀P₀ (basal feed + 0 % levan without exposure to pesticide); pesticide control L₀P₁ (basal feed + 0 % levan with exposure to pesticide); L_0.25P₁ (basal feed + 0.25 % levan with exposure to pesticide); L_0.50P₁ (basal feed + 0.50 % levan with exposure to pesticide); and L_0.75P₁ (basal feed + 0.75 % levan with exposure to pesticide). Weight gain% and specific growth rate were significantly higher (p < 0.05) in levan fed groups compared to their non-levan fed counterpart. Highest (p < 0.05) content of ascorbic acid in muscle, liver and brain tissues was observed with higher level of dietary levan. Glucose-6-phosphate dehydrogenase activity decreased with the increasing level of dietary levan in the liver and muscle. Aspartate aminotransferase activity exhibited a second order polynomial relationship with the dietary levan, both in liver (Y = ?1.001x ² + 5.366x + 5.812, r ² = 0.887) and muscle (Y = ?0.566x ² + 2.833x + 6.506, r ² = 0.858) while alanine aminotransferase activity showed third order polynomial relationship both in liver (Y = 1.195x ³ ? 12.30x ² + 35.23x + 9.874, r ² = 0.879) and muscle (Y = 0.527x ³ ? 8.429x ² + 31.80x + 8.718, r ² = 0.990). Highest (p < 0.05) superoxide dismutase activity in gill was observed in the group fed with 0.75 % levan supplemented diet. Overall results indicated that dietary microbial levan at 0.75 % in C. carpio fry ameliorated the negative effects of fipronil and augmented the growth.     

Response of the tropical spiny lobster Panulirus ornatus to protein content of pelleted feed and to a diet of mussel flesh

In an 8‐week growth experiment, juvenile spiny lobsters (Panulirus ornatus) grew best on a feed containing at least 610 g kg^?1 crude protein on a dry matter basis (DM) and a digestible protein to digestible energy ratio of 29.8 mg kJ^?1. The study entailed a six treatment by four replicate randomized block experiment with 222 wild‐caught P. ornatus of mean initial weight (±SD) of 2.5 ± 0.19 g. The lobsters were fed one of five isolipidic feeds (approximately 130 g kg^?1 DM) in which the crude protein was serially incremented between 330 and 610 g kg^?1 DM, or a reference diet comprising the flesh of frozen green‐lip mussels. Lobsters fed the pelleted feeds had high survival (79 ± 4.5%) and responded to increasing dietary crude protein content with progressively higher growth rates, with the daily growth coefficient improving from 0.72% day^?1 with 330 g kg^?1 crude protein to 1.38% day^?1 with 610 g kg^?1 crude protein. Both growth rate and survival were low with the mussel diet (0.80% day^?1and 41 ± 4.5%, respectively). These results demonstrate that tropical spiny lobsters grow well when fed high‐protein, high lipid, pelleted feeds, but feeding on a sole diet of freshly thawed green‐lip mussels was unsatisfactory.     

Vibrio harveyi as a causative agent of mass mortalities of megalopa in the seed production of swimming crab Portunus trituberculatus

Outbreaks of mass mortalities among cultured megalopa of swimming crab (Portunus trituberculatus) occurred in a commercial hatchery during the spring of 2012 in Jiangsu province, P. R. China. Dominant bacteria were isolated and characterized by biochemical reactions, enzyme production, and sequencing analysis of the 16S rRNA, gyrB (DNA gyrase B subunit) genes, and two strains (DY1 and DY2) were selected as representative strains for virulence tests by immersion. The results showed that the characteristics of identified strains consist with Vibrio harveyi; the 16S rRNA and gyrB genes of the tested strains exhibited high similarity with V. harveyi; and the phylogenetic trees constructed using the neighbor-joining method based on 16S rRNA and gyrB genes. Two strains (DY1 and DY2) clustered with the V. harveyi and were supported by a higher bootstrap value, and two strains (DY1 and DY2) were found lethal to the healthy megalopa and juvenile crab. LD ₅₀ of DY1 and DY2 to megalopa and juvenile crab were 2.4 × 10⁶, 3.0 × 10⁶, 1.9 × 10⁶ and 2.5 × 10⁶ CFU/ml, respectively. The results confirmed that the diseased megalopa were infected by V. harveyi. In addition, we analyzed the tested strains (DY1 and DY2) by PCR for the presence of virulence genes that were known in V. harveyi, and the results showed that five virulence genes (luxR, toxR, vhhA, vhhB and pap6) were detected by a specific PCR assay, further supporting the assignment of isolates to V. harveyi and its pathogenicity. To our knowledge, this is the first report of V. harveyi as pathogenic bacteria of megalopa of swimming crab.     

Hafnia alvei as an opportunistic pathogen causing mortality in brown trout, Salmo trutta L.

Strains of Hafnia alvei caused mortalities in brown trout, Salmo trutta L., following intraperitoneal injection with LD₅₀ values ranging between 1.3 × 10⁴ and 2.5 × 10⁷ bacteria fish^??1. These values are considered to represent a high to moderate degree of virulence. Virulent strains were isolated from non-fish sources. Fish surviving the LD₅₀ values continued to harbour the organism in the kidney, suggesting the establishment of a carrier state.     

Nitrogenous and phosphorus excretions in juvenile silver catfish (Rhamdia quelen) exposed to different water hardness, humic acid, and pH levels

This study examined ammonia, urea, creatinine, protein, nitrite, nitrate, and phosphorus (P) excretion at different water hardness, humic acid, or pH levels in silver catfish (Rhamdia quelen) juveniles. The fish were exposed to different levels of water hardness (4, 24, 50, or 100 mg L^?1 CaCO₃), humic acid (0, 2.5, or 5.0 mg L^?1), or pH (5.0, 6.0, 7.0, 8.0, or 9.0) for 10 days. The overall measured nitrogen excretions were 88.1 % (244–423 μmol kg^?1 h^?1) for ammonia, 10.9 % (30–52 μmol kg^?1 h^?1) for creatinine, 0.02 % (0.05–0.08 μmol kg^?1 h^?1) for protein, 0.001 % (0.002–0.004 μmol kg^?1 h^?1) for urea, 0.5 % (0.64–3.6 μmol kg^?1 h^?1) for nitrite, and 0.5 % (0.0–6.9 μmol kg^?1 h^?1) for nitrate, and these proportions were not affected by water hardness or humic acid levels. The overall P excretion in R. quelen was 0.14–2.97 μmol kg^?1 h^?1. Ammonia excretion in R. quelen usually was significantly higher in the first 12 h after feeding, and no clear effect of water hardness, humic acid levels, and pH on this daily pattern of ammonia excretion could be observed. Water hardness only affected the ammonia and P excretion of R. quelen juveniles in the initial and fifth days after transfer, respectively. The exposure of this species to humic acid increased ammonia excretion after 10 days of exposure but did not affect P excretion. An increase in pH decreased ammonia and increased creatinine excretion but did not change P excretion in R. quelen. Therefore, when there is any change on humic acid levels or pH in the culture of this species, nitrogenous compounds must be monitored because their excretion rates are variable. On the other hand, P excretion rates determined in the present study are applicable to a wide range of fish culture conditions.     

Vibrio parahaemolyticus Associated with Mass Mortality of Postlarval Abalone,Haliotis diversicolor supertexta (L.), in Sanya,China

Outbreaks of mass mortality in postlarval abalone, Haliotis diversicolor supertexta (L.), have swept across south China since 2002 and in turn have resulted in many abalone farms closing. Twenty‐five representative bacterial isolates were isolated from a sample of five diseased postlarval abalone, taken 15 d postfertilization during an outbreak of postlarval disease in Sanya, Hainan Province, China in October 2004. A dominant isolate, referred to as Strain 6, was found to be highly virulent to postlarvae in an experimental challenge test, with a 50% lethal dose (LD₅₀) value of 3.2 × 10⁴ colony forming units (CFU)/mL, while six of the other isolates were weakly virulent with LD₅₀ values ranging from 1 × 10⁶ to 1 × 10⁷ CFU/mL, and the remaining 18 isolates were classified as avirulent with LD₅₀ values greater than 1 × 10⁸ CFU/mL. Using both an API 20E kit and 16S recombinant DNA sequence analysis, Strain 6 was shown to be Vibrio parahaemolyticus. It was sensitive to 4 and intermediately sensitive to 5 of the 16 antibiotics used when screening the antibiotic sensitivities of the bacterium. Extracellular products (ECPs) prepared from the bacterium were lethal to postlarvae when used in a toxicity test at a concentration of 3.77 mg protein/mL, and complete liquefaction of postlarvae tissues occurred within 24 h postexposure. Results from this study implicate V. parahaemolyticus as the pathogen involved in the disease outbreaks in postlarval abalone in Sanya and show that the ECPs may be involved in the pathogenesis of the disease.     

Survival and growth of western rock lobster Panulirus cygnus (George) fed formulated diets with and without fresh mussel supplement

Two trials were conducted to compare the growth and survival of western rock lobster Panulirus cygnus post-pueruli and year 1 juveniles fed different diets. Trial 1 compared lobsters fed a formulated pelletised feed developed for Panulirus ornatus supplemented with fresh mussels (Mytilus edulis) two days per week, with lobsters fed a daily diet of pellets. Trial 2 compared lobsters fed the pellet-mussel supplement diet with those fed a daily diet of fresh mussels.In the first trial, diet treatment did not significantly affect survival, although it was higher in tanks supplemented with mussels. Growth of post-pueruli and year 1 juveniles fed the pellet diet (0.03 g/day; 0.14 g/day, respectively) was significantly lower than growth of post-pueruli and year 1 juveniles fed pellet-mussel supplement diets (0.07 g/day; 0.2 g/day, respectively). Year 1 lobsters fed the pellet-mussel supplement diet consumed considerably less pellet (0.27 vs 0.40 g pellet dry matter/day (DM/day)) than those fed pellets indicating that they will preferentially favour mussel over pellet diets. Feed conversion ratio (FCR) was significantly better for lobsters fed the pellet-mussel supplement diet as a result of the poor growth of pellet-fed lobsters.In the second trial, survival was significantly higher for lobsters fed mussels only. Growth of post-pueruli fed a mussel diet (0.14 g/day) was significantly higher than those fed pellet-mussel diets (0.11 g/day), but there was no significant difference in growth for year 1 juveniles (0.33 g/day). Feed intake of mussel on a dry matter basis was higher than pellet intake for both size classes, with mussel intake being more than double pellet intake for post-pueruli (0.20 vs 0.49 g DM/day).Poor growth of P. cygnus on a pellet only diet indicates that the current formulation for P. ornatus may be inadequate for P. cygnus. However, as pellet intake declined dramatically for year 1 lobsters offered a mussel supplement, and pellet consumption was significantly lower than mussel consumption, it is more likely that poor growth may be attributed to inadequate palatability and intake. The similarly good survival of lobsters fed pellet and pellet-mussel diets indicates that the pellet diet is an acceptable maintenance diet for P. cygnus, but is not suitable for maximising growth for this species. Further research is needed to improve palatability, intake and potentially nutritional composition of this pellet diet before its suitability for P. cygnus is assured.     

Pathogenicity of a non-haemolytic Group B Streptococcus sp. in gulf killifish (Fundulus grandis Baird and Girard)

Gulf killifish (Fundulus grandis) were injected intraperitoneally with different bacterial concentrations and the LD₅₀ were 1.4 × 10⁴ at 96 h and 7.5 × 10 at 168 h. No deaths occurred among fish dipped in the bacterial suspension for different time periods or when the fish were exposed to a 50 parts per thousand hyperosmotic solution prior to dip. Fish became infected when they were injured prior to dipping in the bacterial suspension, but crowding and low oxygen concentration did not precipitate infection. No deaths occurred with oral administration of the bacteria. Bacterial count per gram of tissue was determined for both liver and spleen of infected fish at four, 24-h intervals. There was a significant difference (P > 0.12) between the bacterial counts at the different time periods.     

Acute toxicity of emamectin benzoate (SLICE™) in fish feed to American lobster, Homarus americanus

SLICE? (active ingredient 0.2% emamectin benzoate (EMB)), a feed premix developed by Schering‐Plough Animal Health for the control of sea lice on cultured salmonids, is registered for use in several countries and is being prescribed on an emergency basis in Canada and the United States. The concentration of EMB in feed administered to farmed salmon ranges from 1 to 25 μg g^?1. To determine the acute toxicity of the compound to juvenile and adult American lobster (Homarus americanus), commercial salmon feed was coated with SLICE? at a range of concentrations and provided to the animals for 7 d in the laboratory. The LC₅₀ is estimated to be 644 μg g^?1 (95% CI=428, 1275) for adult lobsters and >589 μg g^?1 for stage V and VI juvenile lobsters. The consumption of medicated pellets by adult lobsters decreased significantly with increasing concentration of EMB. Adult lobsters that died during the study had a significantly greater concentration of emamectin B1a in their muscle tissue than those that survived. These results support the conclusion that salmon feed medicated with EMB at the concentrations used by the aquaculture industry is unlikely to pose an acute lethal threat to adult and small juvenile American lobsters.     

The effect of irradiance and temperature on the photosynthesis of two agarophytes Gelidium elegans and Pterocladiella tenuis (Gelidiales) from Kagoshima,Japan

The effect of irradiance and temperature on the photosynthesis of two Japanese agarophytes, Gelidium elegans and Pterocladiella tenuis (Gelidiales), was determined using dissolved oxygen sensors and pulse amplitude modulated (PAM) fluorometry. Gross photosynthesis and dark respiration rates were determined over a range of temperatures (8–36 °C). The highest gross photosynthetic rates were 40.3 and 37.0 mg O₂ g _ww ^?1  min^?1 and occurred at 24.3 and 25.5 °C [95 % Bayesian credible interval (BCI) 20.7–28.0 and 23.4–28.3 °C], respectively. The dark respiration rate in G. elegans and P. tenuis increased with increasing temperature at a rate of 0.10 and 0.31 mg O₂ g _ww ^?1  min^?1 °C^?1 , respectively. Modeling the net photosynthesis–irradiance (P–E) responses of G. elegans and P. tenuis at 20 °C revealed that the net photosynthetic rates quickly increased at irradiance levels below the estimated saturation irradiance of 88 and 83 µmol photons m^?2 s^?1, with a compensation irradiance of 14 and 19 µmol photons m^?2 s^?1, respectively. The highest value of the maximum effective quantum yield (Φ _PSII) occurred at 20.1 °C (BCI 18.9–21.5 °C) and 21.3 °C (BCI 20.2–22.5 °C) for G. elegans and P. tenuis and was 0.49 and 0.45, respectively. These optimal temperatures of Φ _PSII were relatively lower than those determined by the photosynthesis–temperature model of oxygen evolution. The temperature response of these species indicates that they are probably well adapted to the current range of seawater temperatures in the study site but that they are near the boundary of their tolerable limits.     

Effects of container transparency and reflectivity upon oxygen consumption of hybrid lobsters

The effect of intra-specific visual communication on the rate of oxygen consumption of hybrid lobsters (Homarus americanus × H. gammarus) was tested in a partitioned metabolic chamber. Three partition linings were tested: opaque rubber, clear plexiglass, and glass mirror. Short-term mean oxygen comsumption rates observed for lobsters separated by rubber-lined partitions were 8% lower than those of lobsters separated by the clear partitions, and 29% lower than those of lobsters separated by mirrored partitions (P < 0.001).     

Age estimation of Antarctic minke whales <Emphasis Type="Italic">Balaenoptera bonaerensis</Emphasis> based on aspartic acid racemization technique

Counting of the growth layers in the earplugs is the most accepted technique for determining chronological age of Antarctic minke whales; however, unreadable growth layers form in some individuals, especially in young animals. In this study, aspartic acid racemization (AAR) technique was developed for estimating ages in this species with the aim of complementing the age estimated using earplugs. To validate the technique and to determine the specific coefficients for age estimation, the ratio of d and l-enantiomers of aspartic acid (Asp D/L) in lens of 18 whales and 20 fetuses were analyzed and compared with earplug-based age estimates. The equation for age estimation by AAR in this species was as follows: Log_e{[1 + (Asp D/L)_act]/[1 ? (Asp D/L)_act]} = 2.30 × 10^?3 × earplug age (year) + 0.0201 (p < 0.001, r ²  = 0.918). There is a strong correlation between the age estimates by AAR and earplugs. This study was successful in developing the AAR technique for the Antarctic minke whale, and the application of this technique can complement the age estimation of this species based on earplug readings, especially for young animals with unreadable earplugs.     

Effect of dietary supplementation of periphyton on growth,immune response and metabolic enzyme activities in Penaeus monodon

A 60‐day indoor trial was conducted to study the effect of periphyton supplementation on metabolic and immune responses in tiger shrimp, Penaeus monodon. Periphyton developed over bamboo substrate in outdoor tanks (15 m²) was used as dietary supplement for P. monodon (2.02 ± 0.04 g) reared in 1000 L FRP tanks. Graded levels of periphyton were included in shrimp basal diets: 0% (P0), 3% (P3), 6% (P6), 9% (P9) and P0 diet with natural periphyton (NP) over bamboo substrate. At the end of the trial, P6 and NP showed significantly higher (P < 0.01) growth rate, 23.9% and 20%, respectively, compared with control, P0. Comparatively, lower level of metabolic enzymes, such as lactate dehydrogenase, malate dehydrogenase, aspartate aminotransferase and alanine aminotransferase, was recorded in treatments P3, P6 and NP compared with control, P0. The periphyton‐supplemented group, P3 had significantly higher (P < 0.05) superoxide dismutase (15.83 ± 0.96) and catalase activity (15.73 ± 0.69) compared to 6.88 ± 2.84 and 9.15 ± 0.67 unit mg^?1 protein min^?1_, respectively, in P0. Similarly, higher total haemocyte counts, 32.58 ± 1.30, 28.51 ± 3.12 and 27.26 ± 4.43 × 10⁶ cells mL^?1_, were recorded in P6, NP and P3, respectively, compared to P0, 23.57 ± 1.80 × 10⁶ cells mL^?1. After challenge with Vibrio harveyi, P3 recorded the highest relative percentage survival 67% followed by NP (58%) and P6 (42%) compared with control. However, treatment with highest periphyton inclusion (P9) did not differ significantly with P0 on growth and immunological parameters. This study indicates that periphyton supplementation at 3–6% level improves growth, immune response and metabolic activities in P. monodon.