Etroplus Maculatus Research Articles

Exposure to the plasticizer dibutyl phthalate causes oxidative stress and neurotoxicity in brain tissue.

The phthalate ester, dibutyl phthalate (DBP), is one of the endocrine-disrupting chemicals detected in various aquatic environments. Previous research has found multiple toxic effects of DBP in aquatic organisms; however, the neurotoxic effects of the compound are surprisingly scanty. The purpose of this study was aimed to evaluate the role of oxidative stress in the induction of neurotoxicity in the brain tissue of the fish Pseudetroplus maculatus. The fish were exposed to the sublethal concentration of DBP (200µg L-1) for 1, 4, 7, and 15days along with control and vehicle control groups. The induction of oxidative stress in the brain subcellular fractions was proved by alterations in the activities of superoxide dismutase, catalase, glutathione reductase, and glutathione peroxidase along with the reduction in the total antioxidant capacity. Meanwhile, the levels of hydrogen peroxide and lipid peroxidation were increased. Neurotransmitters such as acetylcholine, dopamine, adrenaline, noradrenaline, and serotonin were altered in all subcellular fractions suggesting the disruption of the neurotransmitter system in the fish brain. These results indicate that DBP induces oxidative stress, which correlates with neurotoxicity in Pseudetroplus maculatus brain tissue.

Occurrence, persistence, and ecological risk of bisphenol A in surface water receiving raw leachate from a municipal solid waste open dump in Kerawalapitiya, Sri Lanka

AbstractBisphenol A (BPA) is an anthropogenic chemical compound utilized to manufacture a wide range of consumer products, such as polycarbonate, polyvinyl chloride (PVC), food packages, and thermal papers. Because of its extensive worldwide use, BPA is pervasive in the environment, negatively affecting aquatic life. Therefore, we studied the occurrence, persistence, and ecological risk of BPA in surface water receiving raw leachate from a municipal solid waste (MSW) open dump in Kerawalapitiya, Sri Lanka. Our findings corroborate that the BPA average concentrations in the canal network were 0.4–42.6 µg/L during the wet season and 0.2–4.9 µg/L during the dry season. The levels of BPA at 11 locations (out of 16) during both seasons differed significantly from the upstream sample, where there was no impact from the dump site (p < 0.05), indicating the ubiquitous occurrence and persistence of BPA in the canal network. BPA levels in the waterbodies are greater in the wet period than in the dry period because of the continuous ingress of run‐off‐driven leachate to the canal network. Our study infers that pH and salinity correlate positively with BPA, while temperature, DO, and TSS are negatively correlated with BPA. BPA levels in five locations during the wet season and one during the dry season surpassed the tolerable level of BPA stipulated by the Canadian Federal Environmental Quality Guidelines to safeguard aquatic life, which is 3.5 µg/L. The findings of the acute ecological risk assessment articulate that during the wet season, Mozambique tilapia (Oreochromis mossambicus) and orange chromide (Etroplus maculatus) constitute a high acute risk, while they pose a medium acute risk during the dry season. Our study suggests that the relevant authorities must prevent the ingress of runoff rich with BPA onto the canal network to protect aquatic life.

Pathophysiological Changes in Response to the Pathogens Administered to Healthy Etroplus maculatus (Teleostei: Cichlidae) and Puntius ticto (Teleostei: Cyprinidae)

The pathogens in fish generate alterations in physiology of fish with consequences in life function decreasing and death. Objective. To analyzed the response of ornamental fish Etroplus maculatus (Teleostei: Cichlidae) and Puntius ticto (Teleostei: Cyprinidae) infected by Pseudomonas aeruginosa (PSA1) and Enterobacter cloacae (EMS1). Methods. Strains of bacteria Pseudomonas aeruginosa (PSA1) and Enterobacter cloacae (EMS1) were obtained from moribund individuals of Etroplus maculatus (Teleostei: Cichlidae) and Puntius ticto (Teleostei: Cyprinidae), also hemaglobin, hematocrit, erythrocyte, and hemoglobin in an erythrocyte, oxygen consumption and ammonium excretion, and histological studies were measured. Results. Hematological parameters (hemaglobin, hematocrit, erythrocyte, hemoglobin in an erythrocyte) denoted an inverse relation with bacterial infection for both species, which was supported by high oxygen consumption, high ammonium excretion, and cell damage showed using histological analysis. Conclusions. These results are similar to observations for inland water and marine fish under culture conditions. The artificial infection of two fish species with two pathogen bacteria generates effects in pathophysiology and can be used for the development of treatment approaches.

Age and growth study of two fin fish species from a tropical estuary

Data on two fin fish species were collected from the Cochin estuary (part of the Vembanad–Kol wetland system) from January 2018 to December 2019. The present study presents the first findings on fisheries demographics in these estuaries, based on length–frequency​ data, to calculate vital demographic dynamic factors and estimate the stock of these commercially important fish species. A variety of evaluations was conducted using the FiSAT II program. Pseudetroplus maculatus had an asymptotic length (L) of 97.6 mm as well as a growth constant (K) of 1.2 year-1. For all the species studied, the age at zero-length (t0) had been calculated and varied from −0.095 to −0.2. Gerres setifer had longevity (tmax) of 5.66 years and a growth performance index (ϕ) of 4.03, whereas P. maculatus had 2.5 and 4.06. P. maculatus had overall mortality (Z), natural mortality (M), and fishing mortality (F) of 3.04, 1.45, and 1.58 year1, respectively, while G. setifer had 1.14, 0.77, and 0.37 year1. The present exploitation level is greater than the optimum exploitation rate, according to the relative yield per recruit (Y/R) study, indicating over-exploitation of three examined finfish species and moderate exploitation for two species. Management measures such as mesh size limitations, restricted fishing efforts, and the proclamation of restricted seasons are required to save these species from extinction.

First report of Crassiphiala sp. (Trematoda: Diplostomidae) as an etiological agent of black spot disease in commercial ornamental fish from Brazil.

Ornamental fish are becoming increasingly popular, but the lack of knowledge regarding their various diseases is a major challenge. Skin diseases commonly found in freshwater fish include black spot disease (BSD), which is characterized by melanin deposits around the metacercariae of some trematode species. Since BSD remains poorly understood, this study describes an outbreak of BSD in Etroplus maculatus raised in outdoor ponds at a Brazilian fish farm. Metacercariae samples were collected, examined, and subjected to molecular phylogenetic analysis. The parasites were conspecific to an unnamed species, Crassiphiala lineage 5, recently found in Brazilian birds (Megaceryle torquata). Sequences obtained for longifurcate cercariae of the planorbid snail Biomphalaria straminea from the same region were identical to our metacercariae of Crassiphiala sp. These results suggest that Biompahalaria snails are likely an intermediate host of this parasite on farms where E. maculatus was found to be infected. We provide the first molecular evidence that Crassiphiala are the causative agents of BSD in fish from Brazil. Combatting snails and preventing access of fish-eating birds to outdoor ponds are strategies to control this disease in ornamental fish farms.

A Pilot Study on The Population Genetic Structure of the Selected Fish Species from Meenachil River, India

Meenachil River is the only river originating from Southern Western Ghats of India having human settlement right from the headwaters to the mouth. The river is subjected to human-induced stressors to varying extents, resulting in a drastic decline in riverine health and fish diversity. The population genetic structure of two species commonly distributed in different geographical zones of Meenachil River, Dawkinsia filamentosa and Pseudetroplus maculatus were studied using the 16S mitochondrial ribosomal RNA gene sequences. Haplotype clustering and the presence of unique haplotypes were identified by phylogenetic and network analysis. Six haplotypes were identified for D. filamentosa and ten for P. maculatus. The neutrality estimations of the upstream and midstream populations of the species revealed the presence of an excess of common alleles with neutral mutations indicating a population expansion after bottleneck and stabilizing selection. The downstream population revealed the presence of an excess of rare alleles with non-neutral mutations indicating a positive directional selection and population sub-division. Population expansion demonstrated star-like phylogenies with rare haplotypes separated by mutational steps from the ancestral haplotypes. The private haplotypes indicated the existence of selection pressure in the downstream zone of the river.

Economic valuation of gillnet fishing in Vembanad Lake, Kerala, South India, using market price approach

Gillnet is the most widely followed selective and passive fishing gear system in all water bodies, especially in the traditionalfishing sector. Many past studies on gillnet fishing in the Vembanad Lake, Kerala, South India focussed on speciesavailability and gear-wise catch of major fishes and showed that there was a significant reduction in the fish catch.Thepresent study used market-based valuation method to estimate economic value generated through gillnet fishing operationin selected village panchayats spreading across three districts viz., Ernakulum, Alappuzha and Kottayam, bordering theVembanad Lake, during the period in 2019-20. The species-wise quantity and value of finfishes and shellfishes caught inthe gillnets from Vembanad Lake, in the three districts were analysed during the survey period. The total number of gillnetfishers living around the Vembanad Lake is about 6157 and the catch was estimated at 4645.97 t of both finfish and shellfishspecies, out of which shrimps formed around 72%. The maximum quantity of catch was observed for catfishes (Arius spp.)at 278.6 t per annum, which fetched a value ₹4.46 crores, followed by Etroplus maculatus at 149 t (₹3.58 crores in valueterms). The economic value generated through gillnet fishing is estimated at ₹57.94 crores. Keywords: Economic value, Gillnet fishing, Market price method, Vembanad Lake

Length-weight relationship of twelve fin fish species from a Tropical Estuary

Length–weight relationships (LWRs) of twelve fish species: Planilizaplaniceps, Planilizaparsia, Etroplussuratensis, Pseudetroplus maculatus, Oreochromis mossambicus, Gerres setifer, Scatophagus argus, Escualosathoracata, Carangoidspraeustus, Caranxheberi, Deveximentuminsidator, Nuchequllablochiiwere examined from Cochin estuary. Fish were caught between March 2019 to February 2020 by various gears like ring seine (mesh size of 8–26 mm), smaller mesh sized drift gill net (26–90 mm), cast nets with a (15-20 mm). Fish were gathered weekly from Munambam Fisheries Harbour (Lat. 10°1029653N, Long. 76°1022583E), Cochin Fisheries Harbour (Lat. 09°5623273N, Long. 76°1527643E) and Chellanam (Lat. 09°4729503N, Long. 76°1625513E). There are significance in all LWRs with r2 values those are ranged from 0.92 to 0.99 and b values are ranged from 2.61 to 3.37 (p < .001). The study provides new maximum length of E. thoracata.

A comparative study on the sensitivity of selected freshwater fishes against triclosan exposure

Triclosan, a broad-spectrum antimicrobial agent, which is widely used in several pharmaceutical and personal care products, has been known to pose adverse impacts on various groups of aquatic organisms, including fish. The present study aimed to compare the sensitivity of five selected freshwater fishes toward triclosan exposure. The acute toxicity or median lethal concentration (LC50-96 h) of triclosan determined using probit analysis was 1.76 mg L−1 in Anabas testudineus, 448 µg L−1 in Danio rerio, 700 µg L−1 in Gambusia affinis, 1.35 mg L−1 in Oreochromis mossambicus, and 750 µg L−1 in Pseudetroplus maculatus. Based on the length–weight relationship, the lowest condition factor, or K value, was recorded in Danio rerio (0.931) while the highest value was observed in Anabas testudineus (2.343) indicating negative allometric growth. Similarly, the weight of fishes and gill weight declined significantly (p < 0.05) in their respective LC50-96 h groups with concomitant alterations in the rate of oxygen consumption denoting respiratory distress. Triclosan exposure also resulted in the modification of fish behavior and histomorphological damage in gill tissues. The alterations in all parameters tested were more prominent in Danio rerio and thus considered the most sensitive species, while Anabas testudineus comparatively tolerated the toxicant to some extent. The study provides the baseline data that variation in the length–weight relationship is one of the major factors that influences the toxic effects of triclosan on the selected freshwater fishes.

Fish Gills as a Tool for the Assessment of Sublethal Effects of Monocrotophos on a Freshwater Fish, Etroplus maculatus

Agricultural pesticides are nowadays being extensively used for the control of a wide variety of agriculturalpests. The world over, human health is at risk. While on one hand people are dying due to scarcity of food,on the other they are slowly being poisoned by the chemicals used for growing food. Other than targetedpests, pesticides affect a wide range of non-target organisms, such as invertebrates and fin fish inhabitingaquatic environment. The present laboratory study is aimed at assessing the sublethal effects ofmonocrotophos on the gills of Etroplus maculatus, a fresh water food fish as well as an indigenous ornamentalfish of the paddy fields of Kuttanad, the rice bowl of Kerala. Sublethal exposure was done in a static systemand the target organ undergoes histological Hematoxylin-eosin staining procedures. The pathologicalchanges were obviously dose–dependent and maximum severity was noticed in the gills of fishes exposedto the highest sublethal concentrations. The overall changes observed due to the exposure to differentconcentrations of monocrotophos are hypertrophy, hyperplasia, fusion of secondary lamellae, oedematousseparation of respiratory epithelium, lamellar telangiectasis, stasis, filamental blood vessel enlargementand necrosis. Based on the histological lesions observed the index values were calculated. On the basis ofthe index values, No Observable Effect Concentration (NOEC), Least Observable Effect Concentration(LOEC) and Maximum Allowable Toxicant Concentrations (MATC) of monocrotophos to E. maculates werecalculated. The concentration which showed index value less than 10 is taken as NOEC and between 10-20is taken as LOEC. MATC of monocrotophos to E. maculates is estimated as 0.4243 ppm. Based on the MATCthe calculated application factor (AF) was 0.1263. These NOEC, LOEC, MATC and AF so obtained for thisspecies can also be used to assess tentative water quality status for the pollutants in the natural environment,and the AF derived from the laboratory studies can be directly applied to the filed situations, as they are therepresentative sample of Kuttanad. Histopathology is an important biomonitoring tool for the farmers indeciding the concentrations of pesticides before its application into the paddy fields.

Orange Chromide, Pseudetroplus maculatus (Bloch., 1795): A Potential Euryhaline Fish Model to Evaluate Climate Change Adaptations in Fishes

Orange chromide, Pseudetroplus maculatus is a euryhaline species with both ornamental and food value. The species has several attributes similar to other fish model organisms such as smaller size, repeated breeding, ease of maintenance, and higher fecundity. A salinity tolerance study was performed in different salinities (0, 15, and 35 ppt) in triplicate introducing 10 fishes each (5.4 ± 0.08 g) in 12 plastic tanks of 60 L water-holding capacity. Fish were fed with commercial feed (1.2 mm and 40% protein) at 5% of body weight twice daily for 45 days. No significant variation (p&amp;lt; 0.05) in growth and survival was observed during the study indicating the wide salinity tolerance for the species. Experimental breeding of the species in freshwater and seawater (35 ppt) revealed the ability of the species to breed in varying salinities. Lenience in captive broodstock development, pair formation, and year-round natural breeding makes the seed production of the species easier. Characteristics such as multiple spawnings, a prolonged incubation period (48 to 72 hours) useful for elaborative embryonic studies, shorter larval development cycle (25 to 30 days), and better acceptance of live feed (Artemia nauplii and flakes) and commercial feed by the larvae make the species a potential euryhaline ornamental fish model to assess the physiological changes at different salinities. Minimal input requirements and lower capital and operational investments for the seed production of the species make it an ideal model organism for studying the impact of climatic and environmental changes on fish farming in different habitats.

IMPACT OF ORGANOPHOSPHATE PESTICIDES ON THE LIVER OF Etroplus maculatus, A FRESHWATER FISH OF KERALA, INDIA

Water pollution induces histological changes in organisms like fishes and it leads to different changes ranging from biochemical alterations in single cell up to changes in fish population. The present sublethal toxicity study reveals the potential adverse effects of monocrotophos and phosphamidon, two widely used organophosphate pesticides in the paddy fields of Kuttanad, on a freshwater fish, Etroplus maculatus, a true denizen in the paddy fields of Kuttanad. Histopathology was used to assess the nature and extent of pesticide induced pathogenesis in E. maculatus. Liver plays a key role in metabolism and subsequent excretion of xenobiotics. The study reveals histological changes in liver included fatty-vacuolation and the displacement of nuclei to the periphery of the hepatocytes, coalescence of vacuoles, coagulated blood, necrosis, neoplasm, etc. Effects at the histological level are usually considered to be an early warning indicator of potential health impacts.

Histopathology – a Biomonitoring Tool to Characterize the Health Status of Fish in the Paddy Fields of Kuttanad, Kerala, India

High population growth have led to a tremendous intensification of rice production, which in turn has significantly increased the amount of pesticides applied in rice cropping systems. Since pesticides are toxic by design, there is a natural concern on the impact of their presence in the environment on human health and environmental quality. The present study was conducted to assess the nature and extent of pesticide induced pathogenesis in the tissues of gills, liver and kidney of Etroplus maculatus inhabiting the paddy fields of Kuttanad, Kerala, India, which is subjected to long term exposure to sublethal concentrations of a common pesticide, phosphamidon, used in these area. The organ index calculated based on various reaction patterns of the different organs. The study showed that the gills are severely affected, liver is moderately affected and the kidney is the mildly affected organ. As an indicator of pollution, histology represents a useful tool to assess the degree of pollution, particularly for sub lethal and chronic effects.

Cichlids endemic to India are not susceptible to Tilapia Lake virus infection

Infection with Tilapia tilapinevirus, also known as Tilapia Lake virus (TiLV) is responsible for high mortalities in tilapia and its hybrid species and presents a significant threat to the tilapia farming industry. Till date, TiLV infections have not been reported in other cichlids that are co-cultured with tilapia. Nonetheless, as natural host switch is a frequent phenomenon among fish viruses, the current study was undertaken to check the susceptibility of three Indian cichlid species, viz. pearlspot (Etroplus suratensis), orange chromide (Pseudetroplus maculatus), and canara pearlspot (E. canarensis), to TiLV vis-a-vis a susceptible host, Nile tilapia (Oreochromis niloticus) using in vivo and in vitro methods. The experimentally-infected Etroplus spp. did not exhibit any clinical signs of infection. Nile tilapia, on the other hand, exhibited a cumulative mortality of 75% at 12 days post challenge, with clinical signs typical of TiLV disease. Three cell lines derived from Etroplus spp. namely, orange chromide fin (OCF), canara pearlspot fin (CPSF), and pearlspot fin (PSF) cell lines did not show any cytopathic effects (CPE) even after 5 blind passages upon inoculation with TiLV-positive tissue homogenate from tilapia. CPE were apparent in the O. niloticus liver (OnlL) cell line after 72 h and the presence of TiLV was confirmed by RT PCR. Thus, the absence of clinical signs and TiLV-specific amplification in the liver and brain tissues of the experimentally infected Etroplus spp., as well as the absence of CPE and the presence of TiLV genome in the three Etroplus cell lines confirmed that Indian cichlids are not susceptible to TiLV infection.

Demographics and Reproductive Characteristics of Orange Chromidae, Pseudetroplus maculatus (Bloch, 1975) from Cochin Estuary, Southern India

Demographics and Reproductive Characteristics of Orange Chromidae, Pseudetroplus maculatus (Bloch, 1975) from Cochin Estuary, Southern India

Susceptibility of orange chromide, Etroplus maculatus (Bloch, 1795) to experimental infection of Betanodavirus

Viral nervous necrosis (VNN), or viral encephalopathy and retinopathy caused by nervous necrosis virus (NNV), is an acute viral disease of fish, resulting in high mortality globally in cultured marine fish. The pathogen, Betanodavirus belonging to the family Nodaviridae, has been widely documented in both farmed and wild fish, besides in invertebrate species across the habitat barriers. However, cichlid fish, in particular Etroplus species, have a low susceptibility or resistance to this disease. The present study was undertaken to check the susceptibility of a brackishwater cichlid, orange chromide (Etroplus maculatus) through intramuscular injection and immersion challenge by NNV (RGNNV genotype). Intramuscular injection (10 μl) with NNV (105 viral particles ml−1) resulted in cumulative mortality of 50% at 15 days of post-infection (dpi), while immersion challenge in NNV spiked sea water (105 TCID50 ml−1) resulting in a mortality of 25% at 19 dpi. Unlike many marine fish which showed 100% mortality within 3–5 days, E. maculatus challenged through both the routes exhibited severe clinical symptoms for 2–3 weeks followed by a recovery stage and moderate level of mortality. Reverse transcription polymerase chain reaction (RT-PCR) tests on live fish sampled during the course of the experiment and the dead fish exhibiting symptoms in both challenge groups tested NNV-positive. Histological examination of fish in challenged groups showed VNN-specific lesions characterized by vacuolations in the brain and eye with more severe lesions in the injected group than the immersion group. In survived fish, no clinical sign was observed, but NNV could be detected by RT-PCR with moderate to severe vacuolations in the brain and eyes until 30 dpi. Despite the virus entering the body and triggering typical symptoms of VNN, the fish appeared to exhibit moderate resistance with a survival of 50–75%. The results indicate that E. maculatus could serve as a brackishwater fish model to study host-pathogen interaction and development of resistance for potential application in NNV-vaccine studies.

Trophic interactions between native and exotic cichlids in a shallow tropical estuary (Lake Vembanad, India)

Feeding ecology and seasonal diet variation between a non-native (Oreochromis mossambicus) and two native cichlids (Etroplus suratensis and Pseudetroplus maculatus) in a tropical estuary was studied. E. suratensis and O. mossambicus fed predominately on blue green algae, whereas P. maculatus preferred aquatic insects. Trophic niche breadth analysis showed that P. maculatus had a broader diet spectrum than did E. suratensis and O. mossambicus. Feeding strategy analysis through dominant prey items showed that E. suratensis and O. mossambicus preferred blue green algae, whereas P. maculatus relied mostly on animal diet (mainly insects), highlighting food segregation shown by this species compared with the other two large-growing cichlids. The highest diet overlap index value was recorded between E. suratensis and O. mossambicus (0.83), compared with P. maculatus and O. mossambicus (0.69), and E. suratensis and P. maculatus (0.64). Intensity of trophic interdependence among the three cichlids showed that the two, large growing species share available food resources, whereas the smaller species considerably alters its food preference.

Involvement of dibutyl phthalate on male reproductive toxicity in the freshwater fish Pseudetroplus maculatus (Bloch, 1795)

ABSTRACT The testicular toxicity of dibutyl phthalate (DBP) was evaluated on the freshwater fish Pseudetroplus maculatus. The median lethal concentration of DBP for 96 h determined by probit analysis was 2 mg L−1, and its sublethal (0.2 mg L−1) exposure for 1, 3, 4, 7, and 15 d showed no change in the body weight but affected the reproductive parameters. The concentrations of alkali-labile phosphates and total protein in plasma and testis increased significantly (P < 0.05) with increase in the level of estradiol and decrease in testosterone, illustrating the adverse effect of DBP on male reproductive functions. Impairment in testicular steroidogenic enzymes and reduction in serum levels of follicle stimulating hormone (FSH), luteinizing hormone (LH), and thyroid stimulating hormone (TSH) with increase in cortisol suggested reproductive dysfunction and stress response of the fish. Further, failure in the reproductive performance was evidenced by reduction in sperm motility, viability, and sperm count. Histological examination confirmed the absence of spermatozoa, completely disorganized spermatogonia, and spermatocytes in treatment groups, suggesting testicular toxicity of DBP, which may contribute to infertility and decline in fish population in the natural environment.

Induction of immunological, hormonal and histological alterations after sublethal exposure of chlorpyrifos in the freshwater fish, Pseudetroplus maculatus (Bloch, 1795)

The present study investigated the induction of immunological, hormonal and histological changes in the freshwater fish, Pseudetroplus maculatus after sublethal exposure of chlorpyrifos. Fish were exposed to chlorpyrifos at one-tenth (0.661μg/L) and one-fifth (1.32 μg/L) of LC50 value, for 15 and 30 d, along with the respective control group. Innate and adaptive immune responses of the fish against the toxicant exposure were measured using lysozyme, complement (ACH50) levels, phagocytic, nitroblue tetrazolium (NBT), myeloperoxidase (MPO), anti-protease and hemagglutination activities, and IgM concentration. The results revealed that sublethal exposure of chlorpyrifos caused significant (p < 0.05) reduction in lysozyme, ACH50, phagocytic, and anti-protease activities whereas there was significant (p < 0.05) increase in NBT, MPO and hemagglutination levels along with serum IgM concentration. Chlorpyrifos treatment showed significant (p < 0.05) decline in the serum levels of cortisol, thyroid, testosterone and estradiol hormones in duration- and concentration-dependent manner. The major histological lesions noted in liver includes necrosis, vacuolization, hepatocytic and cytoplasmic degeneration, while kidneys showed vacoules, necrosis and rupture in renal tubules and glomerulus, whereas spleen were found with melanomacrophage aggregation and necrosis. Similarly, testis showed remarkable changes like reduction in the number of spermatozoa and disintegrated seminiferous tubules while ovarian lesions include degenerated and empty follicles, few atretic oocytes, reduced size of follicles, and broken theca granulosa. The current findings revealed that the use of chlorpyrifos in domestic and agricultural purposes even at sublethal concentration could affect the non-target organisms including fish, and thereby alter the health status of aquatic ecosystems.

HISTOPATHOLOGICAL CHANGES ON ETROPLUS MACULATUS (BLOCH, 1795) DUE TO ZINC EXPOSURE

The contamination of the aquatic systems with heavy metals from natural and anthropogenic sources has become a global problem which poses serious threats to ecosystems and natural communities. Heavy metals get bio concentrated in organisms that may cause health problems in humans via the food chain. The heavy metal zinc causes most serious environmental contaminations and effects due to its rampant use. In this study sublethal effects of the heavy metal, zinc on the histopathological parameters in fresh water fish, Etroplus maculatus was investigated. The 96 hour LC50 value of zinc was determined by Probit analysis, that was found to be 12.4 mg/L. The liver and kidney samples were collected from fish was exposed to sublethal concentrations of zinc on 14th and 28thdays.The structural deformities observed in the liver tissue showed swelling of hepatocytes, vacuolar degeneration, necrosis, nuclear hypertrophy and cirrhosis with acute haemorrhage where as, kidney showed degenerated renal capsule and renal tubule, edema, necrosis and haemorrhage in the interstetium. The histpathological changes become prominent as the days and concentration of exposure increases. The study thus establishes that zinc is harmful to Etroplus maculatus even in sublethal concentrations and effective management strategies are to be evolved and implemented to protect our water bodies and the organisms from problems of heavy metal pollution.