Grow-out Ponds Research Articles

Comparative efficacy of neem (Azadirachta indica) and non-neem supplemented biofloc media in controlling the harmful luminescent bacteria in natural pond culture of Litopenaeus vannaemei

Impacts of two different biofloc media with and without neem (Azadirachta indica) leave in reducing the pathogenic abundance of luminescent bacteria (Vibrio harveyi, V. parahaemolyticus, V. alginolyticus and V. fisehri) through probiotic development of Bacillus cereus and Lactobacillus sp. were investigated both in summer and autumn seasons in white leg shrimp (Litopenaeus vannaemei) natural grow-out ponds at Rasulpur (21.83 N, 87.86 E), West Bengal, India. Though, the population density of Bacillus cereus and Lactobacillus sp. significantly increased in both the media, biofloc with neem negatively impacted upon them as significantly lower population size in both the seasons was recorded in the water phase and even during autumn in the sediment. Reduction of luminous bacterial population mediated through the probiotic effect of Bacillus cereus and Lactobacillus sp. under both the media (R2 = 0.54–0.90) was more pronounced in summer when increase in total dissolved solids and salinity of water played synergistically with the former. Application of neem as media component of biofloc should be avoided during the low temperature regime like autumn.

Ite faeces syndrome caused by Vibrio alginolyticus and Vibrio fluvialis in shrimp, Penaeus monodon (Fabricius 1798) - multimodal strategy to control the syndrome in Sri Lankan grow-out ponds

ite faeces syndrome caused by Vibrio alginolyticus and Vibrio fluvialis in shrimp, Penaeus monodon (Fabricius 1798) - multimodal strategy to control the syndrome in Sri Lankan grow-out ponds

Physical and chemical characteristics of soil from tiger shrimp aquaculture ponds at Malacca, Malaysia

ABSTRACTSoil physicochemical properties of the growout ponds of black tiger shrimp (Penaeus monodon) were examined in relation to shrimp yields for one production cycle. The culture ponds were old (>5 years) and new (newly constructed) types. Soil texture was silty clay with low sand content and high proportion of clay for both the pond types with alkaline soil pH (7.87–9.71). Organic matter (OM) concentration was higher (7.48 ± 0.01%) in old ponds and positively related (r = 0.58, P < 0.05) with total nitrogen (TN). The major cations (Ca, Mg, and Na) were higher in the soil of old ponds and did not fluctuate significantly during culture. The majority of trace elements, i.e., Fe (349.22 ± 35.7 ppm), Mn (56.19 ± 30.2 ppm), Zn (88.56 ± 8.09 ppm), Al (454.3 ± 200.6), Pb (1.3 ± 0.96 ppm), Co (3.4 ± 0.2), V (6.56 ± 1.79 ppm), Cr (19.32 ± 0.63 ppm), Ti (82.78 ± 54.3 ppm), As (5.60 ± 0.28 ppm), Ag (0.38 ± 0.5 ppm), and Sb (3.89 ± 0.48 ppm) were found to be higher in new pond soils than the old ponds. Except for soil manganese, no major fluctuations in trace elements were observed during the culture period. Shrimp growth was not significantly different in the two types of ponds, and no distinct correlation between shrimp growth and element content of soils could be drawn. The results indicate that shrimp pond age may not affect production of shrimp if soils are properly managed pre- and postculture. The differences in production in different ponds might be the result of management practice such as quality of shrimp post larvae, pond preparation, water and feed quality, and available live feed in the pond bottom or other environmental factors like water nutrients and physicochemical parameters.

Comparing nutrient budgets in integrated rice-shrimp ponds and shrimp grow-out ponds

Saltwater intrusion has become a severe issue for the Mekong Delta in Vietnam, especially near the coastline. This issue has led to farmers diversifying from exclusively growing rice to adopting a mixed rice-shrimp system with rice only cultivated in the wet season. However, the nutrient (nitrogen, phosphorus and carbon) cycling and nutrient use efficiency of this system remain poorly understood. To address this knowledge gap, we examined nutrient budgets across 12 farms using integrated rice-shrimp ponds, and in some cases semi-intensive or intensive shrimp grow-out ponds (Penaeus monodon or Penaeus vannamei), over a two-year period (2014–2015). In terms of nutrient budgets, the main nutrient input (92% of the N input, 57% P and 95% C) in the integrated rice-shrimp ponds (IRSPs) came from intake water (excluding C from primary production), while water discharge accounted for the highest output (75% of N output, 41% P, 57% C, excluding C from respiration). The study showed that IRSPs had low dissolved oxygen and high nutrient concentrations which may affect shrimp production. Conversely, salinity levels in the wet season were too high for rice plants thereby affecting rice production. Shrimp survival in the IRSPs was low over the two years (6.3±2.2%), which resulted in the low proportion of nutrients exported from the ponds as harvested shrimp (6% N, 5% P and 10% C). In contrast, the shrimp grow-out ponds (SGOPs), had much higher survival (77.1% for P. vannamei and 59.2% for P. monodon) in three of the six farms where the shrimp survived through to harvest. In these ponds, formulated feed was the highest nutrient input (P. vannamei: 82% N, 75% P and 85% C; P. monodon: 75% N, 55% P and 77% C) with approximately a third of the nutrients being in the shrimp harvest. In our study, nutrients in the IRSPs were used less efficiently than in SGOPs, hence mechanisms to improve shrimp survival and production in IRSPs are urgently needed.

Effect of orally administered vibrio bacterin on immunity, survival and growth in tiger shrimp (Penaeus monodon) grow-out culture ponds.

Administration of vibrio bacterin in feed as a top dressing induced immune stimulation as indicated by higher levels of total haemocyte count and prophenoloxidase. Further reduction in percentage of animals with anatomical deformities suggests the protection against subclinical bacterial infections. The overall improvement in the production parameters like, average daily gain, survival, feed conversation ratio and production in different shrimp stocking densities under commercial farming conditions suggested the possible development of an immune stimulant product based on the inactivated vibrio bacteria for improved health and production in Penaeus monodon shrimp farming.

Microbiome Dynamics in a Shrimp Grow-out Pond with Possible Outbreak of Acute Hepatopancreatic Necrosis Disease

Acute hepatopancreatic necrosis disease (AHPND) (formerly, early mortality syndrome) is a high-mortality-rate shrimp disease prevalent in shrimp farming areas. Although AHPND is known to be caused by pathogenic Vibrio parahaemolyticus hosting the plasmid-related PirABvp toxin gene, the effects of disturbances in microbiome have not yet been studied. We took 62 samples from a grow-out pond during an AHPND developing period from Days 23 to 37 after stocking white postlarvae shrimp and sequenced the 16S rRNA genes with Illumina sequencing technology. The microbiomes of pond seawater and shrimp stomachs underwent varied dynamic succession during the period. Despite copies of PirABvp, principal co-ordinates analysis revealed two distinctive stages of change in stomach microbiomes associated with AHPND. AHPND markedly changed the bacterial diversity in the stomachs; it decreased the Shannon index by 53.6% within approximately 7 days, shifted the microbiome with Vibrio and Candidatus Bacilloplasma as predominant populations, and altered the species-to-species connectivity and complexity of the interaction network. The AHPND-causing Vibrio species were predicted to develop a co-occurrence pattern with several resident and transit members within Candidatus Bacilloplasma and Cyanobacteria. This study’s insights into microbiome dynamics during AHPND infection can be valuable for minimising this disease in shrimp farming ponds.

Isolation of Potential Bacteria as Inoculum for Biofloc Formation in Pacific Whiteleg Shrimp, Litopenaeus vannamei Culture Ponds.

A new green technology to reduce environmental damages while optimizing production of Pacific Whiteleg shrimp, Litopenaeus vannamei was developed known as "Biofloc technology". Microbial communities in biofloc aggregates are responsible in eliminating water exchange and producing microbial proteins that can be used as supplemented feed for L. vannamei. This study aimed to isolate and identify potential bioflocculant-producing bacteria to be used as inoculum for rapid formation of biofloc. For the purpose of this study, bacterial communities during 0, 30 and 70 days of culture (DOC) of L. vannamei grow-out ponds were isolated and identified through phenotypic and 16S rDNA sequences analysis. Phylogenetic relationships between isolated bacteria were then evaluated through phylogenetic tree analysis. One-way analysis of variance (ANOVA) was used to compare the differences of microbial communities at each DOC. Out of 125 bacterial isolates, nine species of bacteria from biofloc were identified successfully. Those bacteria species were identified as Halomonas venusta, H. aquamarina, Vibrio parahaemolyticus, Bacillus infantis, B. cereus, B. safensis, Providencia vermicola, Nitratireductor aquimarinus and Pseudoalteromonas sp., respectively. Through phylogenetic analysis, these isolates belong to Proteobacteria and Firmicutes families under the genera of Halomonas sp., Vibrio sp., Bacillus sp., Providencia sp., Nitratireductor sp. and Pseudoalteromonas sp. In this study, bioflocculant-producing bacteria were successfully identified which are perfect candidates in forming biofloc to reduce water pollution towards a sustainable aquaculture industry. Presence of Halomonas sp. and Bacillus sp. in all stages of biofloc formation reinforces the need for new development regarding the ability of these species to be used as inoculum in forming biofloc rapidly.

Feasibility of dsRNA treatment for post-clearing SPF shrimp stocks of newly discovered viral infections using Laem Singh virus (LSNV) as a model

Using post-larvae derived from specific pathogen free (SPF) stocks in penaeid shrimp farming has led to a dramatic increase in production. At the same time, new pathogens of farmed shrimp are continually being discovered. Sometimes these pathogens are carried by shrimp and other crustaceans as persistent infections without gross signs of disease. Thus it is that a 5-generation stock of Penaeus monodon SPF for several pathogens was found, post-stock-development, to be persistently-infected with newly-discovered Laem Singh virus (LSNV). In this situation, the stock developers were faced with destroying their existing stock (developed over a long period at considerable cost) and starting the whole stock development process anew in order to add LSNV to its SPF list. As an alternative, it was hypothesized that injection of complementary dsRNA into viral-infected broodstock prior to mating might inhibit replication of the target virus sufficiently to reduce or eliminate its transmission to their offspring. Subsequent selection of uninfected offspring would allow for post-clearing of LSNV from the existing stock and for conversion of the stock to LSNV-free status. Testing this hypothesis using the LSNV-infected stock described above, we found that transmission was substantially reduced in several treated broodstock compared to much higher transmission in buffer-injected broodstock. Based on these results, the model is proposed for post-clearing of SPF stocks using dsRNA treatment. The model may also be applicable to post-clearing of exceptional, individual performers from grow-out ponds for return to a nucleus breeding center.

First incidence of loose-shell syndrome disease in the giant tiger shrimp Penaeus monodon from the brackish water ponds in Bangladesh

ABSTRACTThe recent incidence of loose-shell syndrome disease (LSSD) in grow-out shrimp ponds appears to be a major problem in Bangladesh. Therefore, the aims of our study were (i) to observe clinical signs of LSSD to confirm its incidence and (ii) to identify the probable causative agents for LSSD in shrimp. Sampling was conducted randomly from five LSSD-affected ponds and three non-affected ponds near Bakkhali River; ecological parameters were measured. A total of 180 healthy shrimps were used for this experiment, where LSSD-affected shrimp extracts were either injected into the shrimps or mixed with water in the experimental tanks. Finally, microbial examinations were performed to identify the possible LSSD causative agents from the infected individuals. The total shrimp production was higher in ponds with healthy populations (185 kg/ha) than from LSSD-affected ponds (126–146 kg/ha); the survival rate of shrimp at harvest was significantly different (p < .01) between normal and LSSD-affected ponds. The prevalence of infection with white spot syndrome virus (WSSV) and monodon baculovirus (MBV) was found to be lower than that of the Vibrio infections. During the investigation, 8% of LSSD-affected individuals were WSSV positive and 5% were MBV positive, and 4% were infected by both. Our study suggested that the prevalence of LSSD in tiger shrimp might be associated with multiple Vibrio bacterial infections, poor soil and water quality, as well as poor pond management.

Impact of commercial probiotics application on growth and production of giant fresh water prawn (Macrobrachium Rosenbergii De Man, 1879)

The study was conducted to observe the impact of commercial probiotics application on growth and production performance of fresh water prawn (Macrobrachium rosenbergii) from August 2011 to March 2012. There were four experimental groups viz (a) control or without probiotics treated prawn (T1), (b) feed probiotics- Zymetin (T2) treated prawn, (c) soil probiotics- Super PS (T3) treated prawn and (d) Both Zymetin and Super PS (T4) treated prawn. Twelve ponds (each 120m2) were used where stocking density was 2/m2 for all treatments and control and each was triplicated. After pond preparation, prawn PL was reared in the nursery pond for 45days to become juvenile. At the time of stocking in growout ponds, average body weight of juvenile prawn was 1.04g. After eight months (240days) of culture, the mean final weight became 39.5±12.03, 43.4±14.91, 48.0±16.73 and 51.6±15.58g in T1, T2, T3 and T4 respectively. Significance difference was found among all treatments and T4 showed highest growth. The SGR was found to be 1.50±0.13, 1.53±0.13, 1.58±0.13 and 1.61±0.11 (%BW/day) in T1, T2, T3 and T4 respectively and the difference was significant. The survival rate did not differ significantly but highest survival rate was found in T4 (90%). The average FCR was significantly lowest in T4 (1.39) and highest in T1 (1.9). The net average production was found to be significantly higher in T4 (914kg/ha) which was 35% and 21 % higher than the control group (T1) and feed probiotics (T2) respectively. Water and soil quality parameters were measured and were within the culturable range. The production of probiotics treated ponds was always higher than without probiotics treated ponds but highest growth and production were found in T4 where Zymetin and Super PS were used combinedly. The results of this study can be applied in the farmer’s pond to increase the total production of prawn in the country.

Influence of juvenile stunting on grow-out performance of rohu, Labeo rohita (Hamilton, 1822)

Summary Rohu Labeo rohita juveniles stunted for 2, 4, 6, 8 10 and 12 months at 20 and 40 m−3 densities were subsequently cultured for 1 year in six grow-out earthen ponds each 0.09 ha. Each pond was stocked with juveniles stunted for a particular duration (treatment) at a combined density of 8,000 ha−1 from two density groups at a 1:1 ratio. Electronic tags were implanted in 20 juveniles of each density group in all treatments as sub-samples to track fish growth per individual. Another grow-out study evaluated the growth of a fresh batch of rohu juveniles against similar sized but stunted 12-month-old juveniles, stocked together at 8,000 ha−1 density (1:1). Thirty juveniles from each group in this pond were tagged. After the year-long grow-out phase, survival (85.6%–96.3%) showed a positive correlation with the juvenile stunting duration. The study revealed a minimal influence of stunting density on juvenile growth in a subsequent grow-out phase when they were stunted up to 8 months. But a higher stunting density (40 m−3) favoured growth in juveniles stunted for longer periods (>8 months). Growth curves of the lower and higher stunting density groups as well as “all rohu populations” in the treatments showed convergence with those of control (2 months stunted) only in the 4-month stunted juveniles. The growth convergence in this treatment was achieved within 6 months of culture and subsequently surpassed that of control to over-compensate at the end of 12 months of culture. No such compensatory growth (CG) response was observed in the 6- to 12-month stunted rohu, because the growth curves run almost parallel to each other. The study also revealed juvenile stunting for more than 6 months delayed the initiation of the growth recovery process in the stunted individuals during their subsequent grow-out phase. In the second study, identical growth trajectories of the fresh batch and the year-long stunted juveniles reaffirmed a non-existence of CG activity in the later. Such results indicate that juvenile stunting in rohu for 6 months and beyond does not lead to a better fish yield or economic gain to farmers, but rather adds to the investment costs because of the need for more feed and maintenance during stunting.

Performance of Litopenaeus vannamei postlarvae reared in indoor nursery tanks under biofloc conditions at different salinities and zero-water exchange

Shrimp farming at low salinity is a trend that will continue to grow globally. Performance of Litopenaeus vannamei postlarvae in the nursery at different salinities with a biofloc technology (BFT) system needs to be explored further, as the nursery is currently used as a transitional stage between the hatchery and grow-out ponds. Hence, this study evaluated the effect of seven salinity levels (2, 4, 8, 12, 16, 25, and 35 ‰) on the performance of L. vannamei postlarvae reared with a BFT system and zero-water exchange at 2000 org/m3. Additionally, this study evaluated the water quality of all salinity treatments. After 28 days of culture, the findings showed that, under biofloc conditions, salinity affected the performance of some variables of water quality in some cases, but only the combination of a high nitrite-N concentration (>4 mg/l) and low salinity (2 and 4 ‰) caused up to 100 % shrimp mortality in the first 2 weeks. In the rest of the treatments (8, 12, 16, 25, and 35 ‰), shrimp survival was >72 %. Shrimp mortality was affected by salinity, especially when it decreased from 35–25–16 to 12 and 8 ‰. The organisms reared at low salinities presented lower final weights and specific growth rate than those reared at higher salinities. An inverse relationship was shown between the ion concentration and the final weight of shrimp.

Bopyrid isopods parasitizing on the cultured fresh water prawn, Macrobrachiummalcolmsonii in South India.

The bopyrid isopods are common in wild Macrobrachium spp. but not common in aquaculture condition. This is the first study that reports the parasitizing of bopyrid isopods on the cultured M. malcolmsonii. Bopyrid isopod (Probopyrus buitendijki) was identified in the branchial cavities of the fresh water prawn, M. malcolmsonii from grow-out culture pond at Kuriyamangalam, India. Macrobrachium malcolmsonii is a new host for P. buitendijki. A total of 1323 M. malcolmsonii were checked for this study. The overall prevalence of the parasitic infestation was reached 46.2%. The parasitic infection was higher in female (83%) than in male (3.4%). Highest prevalence of infestation was found in the median size group (7-8cm) (58.7%). Infected females were not berried unlike uninfected prawns. The parasites cause infertility and does not found any organ deformities due to the infestation. The parasite was inversely attached in the gill chamber with no lesion on the gill but the infected branchial chamber became bulged.

BIOECONOMIC ANALYSIS OF COMMERCIAL POND CULTURING OF THE STRIPED CATFISH Pangasianodon hypophthalmus IN THE MEKONG DELTA, VIETNAM

An analysis of costs and returns for striped catfish grow-out pond culturing in the Mekong Delta, Vietnam taking into consideration the factor of geographical location, was conducted. The geographical location not only had an influence on the cost but also the profitability of the enterprise. Multivariate statistical analysis showed a decline in the operating costs and benefits, depending on the location, being highest in middle stream ponds, less in upstream ponds and finally lowest in downstream ponds. However, the earning power of downstream ponds was highest, in terms of profitability associated with fingerlings, feed and energy. Cobb Douglas production function analysis revealed that net revenue earned from increasing the scale of production would increase if feed cost input rose, but whereas net revenue would decrease with an increase of input medication costs. The statistic results also showed that the size of fingerlings from middle stream ponds (1.83 cm high), the stocking density from upstream ponds (47.17 fingerlings /m^2), and the weight of fish harvested from downstream ponds (0.86 kg/fish) are suitable for farming. Various levels of government could propagate suitable policies and put in place infrastructure to encourage farmers to use electricity for fuel instead of petroleum, to apply Global GAP (global agricultural practices) standards in production activities, to improve the competitive capacity of domestic feed processing companies, to expand fry nursery areas at downstream sites, and to increase fish prices through awareness campaigns designed to increase global demand.

Genetic Assessment for Growth Performance in Diallel Cross of Wild and Cultured Giant Freshwater Prawn, Macrobrachium rosenbergii

The present study evaluates the growth performance of wild and cultured strains of giant freshwater prawn (GFP) in 2 × 2 diallel crosses as an initiation to improve its aquaculture production. A wild population was sampled from Vembanad Lake (Kerala) and from the farm-reared strain domesticated and cultured for several generations from grow-out ponds (Tamilnadu). From the four cross-combinations juveniles were produced using single pair mating. A total of 3,840 prawns (1,528 males and 2,312 females) were harvested after 15 weeks of grow-out hapas culture. The fixed effect included in the model was sex (male or female) and the age at harvest fitted as linear covariates. Total length, total weight, and carapace length of each prawn were recorded at the harvest. Additive genetic estimates of the crosses showed that the wild stock had higher length and weight (12.17% and 22.33%), while the cultured stock had lower length and weight (−18.26% and −22.98%). However, the average heterosis in the crossbred stock increased (0.84% and 6.70%) with reduced carapace length (1.34%) when compared with that of wild and cultured stock and had an additive genetic effect with increased body weight when compared with cultured stock. Genetic diversity data obtained for the wild, cultured, and crossbred stock using five microsatellite loci show increased observed and expected heterozygosity with decreased FIS (inbreeding coefficient) in the crossbred stocks when compared with that of cultured stock. The result suggests that additive genetic effects along with the heterosis are largely responsible for relative strain performance and hence, selection based on these strategies could improve the cultured stock of M. rosenbergii.

Improving water-use efficiency for Ictalurid catfish pond aquaculture in Northwest Mississippi, USA

We used a 50-year (1961–2010) daily record of precipitation and evaporation in a hydrological model to simulate ground water withdrawal for the foodfish grow-out phase of ictalurid catfish culture in northwest Mississippi, USA. The model quantified the effects of seepage, reusing water for multiple years, and managing water levels to capture rainfall (drop-fill water management). Selecting sites with relatively impervious soils and reusing water for multiple years had large impacts on annual water use, and combining those practices with drop-fill water management reduced simulated groundwater withdrawal to less than 60 cm year−1 compared with more than 450 cm year−1 for the least conservative scenario. Water conservation measures reduced estimated costs of pumping ground water from ~$1150 ha−1 year−1 for the least conservative set of water-use variables to less than $110 ha−1 year−1 for the best set of water conservation practices. Efficiency of pumped water use was dramatically improved by intensifying production in the foodfish grow-out phase. Combining water-conservation practices with production intensification improved the water use index from 9.18 m3 kg−1 for foodfish grow-out ponds with the least conservative set of practices to 0.28 m3 kg−1 for ponds built on soils with negligible seepage, managed with a 22.9-cm drop/7.6-cm fill, drained every 10 years, and producing 15 000 kg of catfish ha−1 year−1. When simulated ground water use for the best set of water conservation practices in foodfish grow-out ponds was combined with estimates of ground water used for fingerling production and water used in producing grain-based feedstuffs, total consumptive water use index for catfish culture was estimated at ~2.7 m3 kg−1. This index is competitive with most other types of animal agriculture. Efficient water use in catfish farming is easily achieved under commercial conditions using existing simple technologies.

A novel report of fungal pathogen Aspergillus awamori causing black gill infection on Litopenaeus vannamei (pacific white shrimp)

Litopenaeus vannamei (pacific white shrimp) is the most cultured shrimp species which is also susceptible to microbial diseases like other shrimps. In the present study, the fungi, Aspergillus awamori KM434331 caused black gill disease to pacific white shrimp. It was first reported from L. vannamei in shrimp grow out pond located at Vellapallam, Nagapattinam District, Tamil Nadu, India. A. awamori KM434331 was isolated from affected gill of shrimp. Further, its morphological, cultural and phylogenetic characteristics were identified. The histopathological depiction is inflammatory response of L. vannamei against A. awamori KM434331 are haemocytic infiltration, encapsulation, melanization and collagen-like fibre deposition in the gill. In addition to that, Aspergillus awamori KM434331 cause dysfunction of gills that leads to chronic mortality in the grow-out pond of shrimps.

Heavy metal levels in mud crabs (Scylla spp.) from East Bataan Coast.

Heavy metal levels (Pb and Cu) on adult mud crabs (Scylla spp.) from the East Bataan Coast were determined. Muscle tissue from each crab was processed through nitric acid digestion and analyzed using atomic absorption spectroscopy. The average concentrations in the samples were 3.37 × 10(-3) and 1.01 mg/L-both within WHO acceptable limits. These were contrasted with the levels found in sediments from catch and grow-out sites (17.9, 14.5, 37.8, and 31.3 mg/L) and were found to be significantly lower in concentration. It takes 3-8 months before adult mud crabs can be harvested from grow-out ponds, and the data suggests that the organisms, even when constantly exposed to high levels of Pb and Cu, do not bio-accumulate toxic levels of these heavy metals. Mud crabs constitute a major economic natural resource in the Philippines and in the province of Bataan. Commanding high prices due to the quality of its meat, it is also a preferred culture product due to its impressive size, rapid growth rate, and high flesh content. Mud crab culture in Bataan is primarily driven by grow-out of captured juveniles in pen or pond cultures sourced from nearby bodies of water-making them vulnerable to prolonged exposure to pollutants. The East Bataan Coast shares its waters with the polluted Manila Bay, giving rise to the concern of the quality of seafood acquired from the area.

Loose Shell Syndrome (LSS) in Litopenaeus vannamei grow-out Ponds and its Effect on Growth and Production

Loose shell syndrome is a chronic disease in shrimp industries, in the present study, two different L. vannamei grow-out ponds (normal and LSS infected ponds) were selected to study their water quality parameters. Average Body Weight (ABW) and Daily Growth Rate (DGR) in Prakasam district of Andhra Pradesh. The results of the present study showed, there was no much variation in water quality parameters between both the ponds except pH. The daily growth rate and average body weight was higher in the normal pond than LSS infected one. The maximum LSS prevalence was reached up to 20%. The infected shrimps became sluggish and negative allometric growth. The results of present study revealed that the LSS infected shrimps showed lower production in the grow-out pond.

Ontogenetic Development of Sensory Structures on the Antennules and Antennae of the Giant River PrawnMacrobrachium rosenbergii(De Man)

In this study the occurrence of sensory structures on the antennules and antennae of the giant river prawn Macrobrachium rosenbergii (De Man) during postembryonic ontogenetic development were examined. Larvae and postlarvae were obtained from hatchery recirculating tanks, juveniles from indoor nursery tanks, and adults from earthen grow-out ponds. The animals were fixed with Karnovsky fixative and dissected. Antennules and antennae were removed, metal-coated, and photodocumented using a scanning electron microscope. The antennules have aesthetascs and simple plumose and pappose setae; the antennae have simple, plumose and pappose setae. These structures increase in density, covered surface, and distribution during ontogeny and should be related to chemoreception and mechanoreception. The antennular statocyst that appears during larval stage VII of the giant river prawn has an array of sensory structures that enable the perception of chemical and tactile stimuli beginning with its early life stages. The ontogenetic changes observed allow an inference that initial-stage larvae, advance-stage larvae, juveniles, and adults have different capacities to exploit the environment.