Search

The accumulation trends of Cu, Zn, Pb and Ni and their effects on two native species, Etroplus suratensis and Villorita cyprinoides from Cochin estuary and their biomarker responses were explored. Bioaccumulation and metal selectivity index (MSI) in E. suratensis for gill and liver showed the highest accumulation for Zn (209.33 ± 17.14 mg kg−1) followed by Cu (64.16 ± 8.07 mg kg−1), while in V. cyprinoides Cu showed the highest accumulation (80.78 ± 6.92 mg kg−1) in gill tissue followed by Zn (65.28 ± 7.06 mg kg−1). Histological alterations were evaluated in gill and liver tissues of E. suratensis using histopathological index (Ih) method. Lamellar hyperplasia and deformed lamellar architecture were the evident changes in gill tissue, while the alterations in liver tissues were marked by the presence of melanomacrophage centers and necrotic lesions in liver parenchyma. The high target hazard quotient (THQ) obtained for Pb (0.94) indicated that the daily consumption of aquatic products contaminated with metals Pb, Cu and Zn has obvious health risk to human consumption. Thus, the elevated metal accumulation rate in the tissues with supportive histological changes suggests that these alterations can serve as definite signature of heavy metal contamination in native organisms of Cochin estuary.

Flow cytometry was used for estimating the genome size of five brackishwater finfish and four shrimp species. The genome size for Lutjanus argentimaculatus was 0.95 ± 0.10 and 0.79 ± 0.01 pg for Scatophagus argus. The genome sizes for Chanos chanos (0.72 ± 0.01 pg), Etroplus suratensis (1.71 ± 0.16 pg) and Liza macrolepis (0.87 ± 0.02 pg) which are important aquaculture species are reported for the first time in this study. The phylogenetic tree constructed using sixty-seven sequence accessions of cytochrome c oxidase subunit 1 (COI) gene of Lates calcarifer revealed two separate clades. The Indian Lates calcarifer species with estimated genome size of 0.44 ± 0.02 pg belonged to a clade different than that of South East Asia and Australia reported to have larger genome size. The genome size for the four major species of genus Penaeus (Penaeus monodon, Penaeus indicus, Penaeus vannamei and Penaeus japonicus) were found in similar range. The genome size of female shrimps ranged from 2.91 ± 0.03 pg (P. monodon) to 2.14 ± 0.02 pg (P. japonicus). In male shrimps, the genome size ranged from 2.86 ± 0.06 pg (P. monodon) to 2.19 ± 0.02 pg (P. indicus). Significant difference was observed in the genome size between male and female shrimp of all species except in P. monodon. The highest relative difference of 12.78% was observed in the genome size between the either sex in P. indicus. The interspecific relative difference of 30.59% in genome size was highest between the male shrimps of P. monodon and P. indicus and 35.98% between the female shrimps of P. monodon and P. japonicus. The stored gills and pleopod tissues could be successfully used up to 3 weeks to estimate the genome size in shrimps.

This article discusses bioaccumulation and temporal variation of heavy metals in three edible lagoon fish species with references to gender. Cd and As were undetected in the three fish species (i.e., below the method detection limits of 1 μg Cd/kg wet weight and 2 μg As/kg wet weight) irrespective of the periods, and Cd was undetected in the water too (i.e., below the detection limit of 0.0003 mg/L). Except for Zn (which was mainly available as Zn2+ in the water), Pb was present largely as low labile metal-chloride complexes and As as HAsO4 2− as per Visual MINTEQ, version 3.1. Bio-transfer factors of Sn (which was also undetected in the water; below the detection limit of 0.05 mg/L), Hg, Pb, and Zn were

An experiment was conducted to compare the efficiency of biofilm production in natural and artificial substrates and to study their effect on water quality and growth of Etroplus suratensis. Four different substrates were used for biofilm formation: paddy straw (T1), sugarcane bagasse (T2), polyvinylchloride (PVC) pipe (T3) and plastic sheet (T4). The experiment was carried out in mud-bottomed fibre-reinforced plastic tanks (300 L) in triplicates. About 3000 cm2 surface area (600 g) of each substrate was suspended in water supplemented with fertilizers. Only cow dung and urea were applied in control tanks. The tanks were stocked with 25 fishes with average weight of 9.1 ± 0.22 g. The overall mean value of heterotrophic bacteria in substrate was found higher in straw followed by bagasse, plastic and PVC. The dominant genera of bacteria in the substrate were Bacillus, Pseudomonas and Micrococcus in that order of preponderance. The mean phytoplankton and zooplankton density on the substrates were higher in bagasse followed by straw, plastic and PVC. The biofilm developed on the substrate significantly reduced the ammonia nitrogen and nitrite-nitrogen content of water. The growth of fishes was significantly (P

The present study was conducted to elucidate the osmoregulatory ability of the fish pearl spot (Etroplus suratensis) to know the scope of this species for aquaculture under various salinities. Juvenile pearl spot were divided into three groups and acclimated to freshwater (FW), brackish water (BW) or seawater (SW) for 15 days. The fish exhibited effective salinity tolerance under osmotic challenges. Although the plasma osmolality and Na(+), K(+) and Cl(-) levels increased with the increasing salinities, the parameters remained within the physiological range. The muscle water contents were constant among FW-, BW- and SW-acclimated fish. Two Na+/K+-ATPase α-isoforms (NKA α) were expressed in gills during acclimation in FW, BW and SW. Abundance of one isoform was up-regulated in response to seawater acclimation, suggesting its role in ion secretion similar to NKA α1b, while expression of another isoform was simultaneously up-regulated in response to both FW and SW acclimation, suggesting the presence of isoforms switching phenomenon during acclimation to different salinities. Nevertheless, NKA enzyme activities in the gills of the SW and FW individuals were higher (p 0.05) than in BW counterparts. Immunohistochemistry revealed that Na(+)/K(+)-ATPase immunoreactive (NKA-IR) cells were mainly distributed in the interlamellar region of the gill filaments in FW groups and in the apical portion of the filaments in BW and SW groups. The number of NKA-IR cells in the gills of the FW-acclimated fish was almost similar to that of SW individuals, which exceeded that of the BW individuals. The NKA-IR cells of BW and SW were bigger in size than their FW counterparts. Besides, the relative abundance of branchial Na(+)/K(+)/2Cl(-) co-transporter showed stronger evidence in favor of involvement of this protein in hypo-osmoregulation, requiring ion secretion by the chloride cells. To the best of our knowledge, this is the first study reporting the wide salinity tolerance of E. suratensis involving differential activation of ion transporters and thereby suggesting its potential as candidate for fish farming under different external salinities.

Mercury, a global pollutant, has become a real threat to the developing countries like India and China, where high usage of mercury is reported. Mercury and other heavy metals deposited in to the aquatic system can cause health risk to the biota. The common edible fishes such as Mugil cephalus, Arius arius, Lutjanus ehrenbergii, Etroplus suratensis were collected from Cochin backwaters, Southwest India and analysed for mercury and other heavy metals (zinc, cadmium, lead and copper) in various body parts. Kidney and liver showed highest concentration of metals in most fishes. The omnivore and bottom feeder (E. suratensis) showed high concentration of mercury (14.71 mg/kg dry weight) and other metals (1.74 mg/g—total metal concentration). The average mercury concentration obtained in muscle was 1.6 mg/kg dry weight (0.352 mg/kg wet weight), which is higher than the prescribed limits (0.3 mg/kg wet weight). The concentration of other heavy metals in the muscles of fishes were found in a decreasing order Zn>Cu>Cd>Pb and are well below WHO permissible limits that were safe for human consumption. Metal selectivity index (MSI) obtained for all the metals except mercury showed that both carnivores and omnivores have almost same kind of affinity towards the metals especially Zn and Cd, irrespective of their feeding habit. The MSI values also indicate that the fishes have the potential to accumulate metals. High tissue selectivity index (TSI) values were reported for kidney, muscle and brain for all metals suggests that the metal concentration in these tissues can serve as an indication of metal polluted environment. Even if the daily intakes of Zn, Cd, Pb and Cu from these fishes are within the provisional maximum daily intake recommended by WHO/FAO, the quality is questionable due to the high hazard index obtained for mercury (>1). Fishes like E. suratensis being a favourite food of people in this region, the high consumption of it can lead to chronic disorders as this fish has high concentration of metals.

Highly popular and delicious fish of Kerala (India), pearlspot, Etroplus suratensis is known for its ability to tolerate wide range of salinity, omnivorous feeding behavior. Present report documents the occurrence and management of Caligus rotundigenitalis in brackishwater pond meant for culture demonstration of pearlspot in Gujarat, (India). A brackishwater aquaculture pond (1,500 sq m) was stocked with pearlspot fry (2.60 ± 0.83 g; 4.31 ± 0.82 cm) @ 25,000 ha(-1). On the 46th day of culture couple of dead fish were observed which gradually increased to 120 per day by 52nd day. Following the close observation parasitic infestation was noticed on gills cavities ranging from 15 to 20 numbers per fish. These characteristic features confirmed the parasite as C. rotundigenitalis. As a therapeutic measure the infested pond was successfully treated with Butox(®) @ 300 ml/ha (Deltamethrin 12.5 mg) and repeat dose was administered 2 weeks later. The results of the study suggest the possible therapeutic value of Deltamethrin in treatment of caligid infestation in pond cultured pearlspot.

We studied seasonal changes in feeding habits of size-structured fish assemblages in three freshwater reservoirs in Sri Lanka. We obtained fish samples for diet analysis from three reservoirs during the months of rising water level (RIWL) and receding water level (REWL). During RIWL, peripheral areas with terrestrial/semi-terrestrial macrophytes get inundated, which resulted in increased food availability for macrophyte feeding fish. During REWL, detrital food sources increase due to decaying terrestrial plant material, which has inundated. Based on the dietary habits of individual species in the three reservoirs during RIWL and REWL, it is evident that detritivorous and phytoplanktivorous fish species, which belong to low trophic levels do not show significant variation in dietary habits between the two seasons (e.g. Oreochromis mossambicus, Oreochromis niloticus and Amblypharyngodon melettinus). Stenophagous species such as benthic invertebrate predators (Puntius chola and Puntius dorsalis), macrophytophagous species (Etroplus suratensis and Tilapia rendalli) and zooplanktivorous Hemirhamphus limbatus do not exhibit significant variation in dietary habits between seasons. Also their feeding habits do not vary with body size. Euryphagous species such as Puntius filamentosus on the other hand, exhibit variations in dietary habits between seasons as well as with body size. Stenophagous species, which feed on detritus and phytoplankton and euryphagous species, which exhibit temporal dietary plasticity, are therefore abundant in fish assemblages of these reservoirs.

Sister chromatid exchange (SCE) test was applied to a tropical cultured fish, Etroplus suratensis by exposing to known mutagens. Intramuscular injections of methyl methane sulphonate (MMS) and cyclophosphamide (CP) for an exposure period of 96 h resulted in significant increase in the frequency of SCE in gill tissues. MMS induced dose dependent increase in SCE. The findings revealed that the test species in the present study may be used in mutagenicity assays for screening environmental pollutants.

In two years of sampling, 10 287 fishes belonging to 62 species (39 families) were collected from mangroves and seagrasses of the Negombo Estuary. Of the species collected, 70% were marine, 27% estuarine and 3% freshwater. Aplocheilus melastigma, Ambassis dayi, Etroplus suratensis, E. maculatus, Bathygobius fuscus and Arothron immaculatus constituted 90% of the catch. Sixteen species were caught only from mangroves, 6 only from seagrasses, and 40 from both. The number of species, individuals, biomass and diversity were higher in seagrasses than in mangroves. Gobies and some siganids moved to the mangrove habitat as they grew, but cichlids, triacanthids, some eleotrids and tetraodontids preferred seagrasses. The number of species and individuals caught increased at the beginning of the north-east monsoon when the rainfall was low. The number of species and individual numbers were positively correlated with salinity and dissolved oxygen and negatively correlated with water temperature. Of the 33 species examined, seagrasses formed >25% of the gut content in juvenile Lates calcarifer, Apogon thermalis, E. suratensis, E. maculatus, Siganus javus, Butis butis and Bathygobius fuscus. Mangrove litter was the main gut content of the family Syngnathidae. E. suratensis, E. maculatus and S. javus from seagrasses contained more filamentous algae than seagrasses in their stomachs. S. javus collected from mangroves also contained more seagrasses in their stomachs than mangrove litter, indicating that the association of juvenile fishes with mangroves or seagrasses may not be obligate in estuaries subject to low tidal fluctuations.

The life-cycles of two species of haploporid trematodes, Carassotrema bengalense Rekharani & Madhavi, 1985 and Saccocoelioides martini Madhavi, 1979, are illustrated. The molluscan host of the two species is the prosobranch gastropod Stenothyra blanfordiana (Nevill), which occurs in abundance in Chilka Lake, a large brackish-water lagoon. The cercariae are gymnocephalous, bi-ocellate and distomate. The cercaria of C. bengalense is characterised by the presence of thin lateral expansions of the tail, long tubular caeca, dense cystogenous glands and a Y-shaped excretory bladder. The cercaria of S. martini, on the other hand, has a simple tail, a prominent pharynx, short elliptical caeca lined by tall cells and an I-shaped excretory bladder. Both of the cercariae encyst on algae. Adults of C. bengalense occur in Mugil cephalus L. and Valamugil cunnesius (Val.), while those of S. martini occur in M. cephalus, Liza macrolepis (Smith), Etroplus suratensis (Bloch) and Hilsa ilisha (Hamilton).

1. The present report embodies the results of a study on the karyotypes of 16 teleost species belonging to 15 families and 7 orders,viz., Anguilliformes (1 sp.), Cypriniformes (1 sp.), Siluriformes (1 sp.), Synbranchiformes (1 sp.), Scorpaeniformes (2 spp.), Perciformes (9 spp.) and Tetradontiformes (1 sp.). 2. The diploid chromosome numbers in the 16 species presently studied ranges from 40 to 62. 3. The size of the chromosomes ranges from 0·83 to 5·30µ. 4. No heteromorphic pair or pairs of chromosomes are discernible in any of them: further, a study of the karyotypes in both the sexes ofMystus gulio, Etroplus suratensis, E. maculatus, Mugil cephalus andAnabas testudineus failed to reveal the occurrence of heteromorphism, if any, in them. 5. Based on the available morphological and cytological information, the systematic position and species interrelationships have also been discussed.

Modal action patterns used in maintenance behavior have often been included in animals' communication repertoires during evolution, yet for fish neither the occurrence nor subsequent ritualization of maintenance behavior has been demonstrated. We review the literature and show that one maintenance behavior, the chafe, occurs in at least 30 families of fish. The chafe thus appears to offer a fruitful tool for the phylogenetic analysis of behavior of fish. We show that chafing in Etroplus maculatus and Xiphophorus helleri functions to remove sources of irritation from their skin. We also show that during ontogeny and when in social groups the frequency of chafing does not change with age in E. maculatus and E. suratensis. Etroplus suratensis have about twice the body surface and chafe twice as often as E. maculatus. Chafe-like behavior in Etroplus is observed during ontogeny when young glance on their parents' body. Young E. maculatus without parents present chafe more frequently than young with parents present suggesting that chafing on the substrate may substitute for parent contacting. Chafing is also included in adult behavior where it occurs during pair-formation, nest relief behavior and as an interspecific signal performed by the cleaner E. maculatus upon the host E. suratensis. The maintenance chafe and glance upon the parent both occur rapidly while the chafe performed during pair-formation is slow suggesting a degree of ritualization.

The Asian cichlid fishes, Etroplus maculatus (Bloch) and E. suratensis (Bloch) were observed in their natural habitat. Ecological and behavioral interactions of these species have not been previously reported. E. suratensis benefits from being cleaned by E. maculatus; it is doubtful the ingestion of parasites and fungi is of much direct benefit to E. maculatus. The advantage to E. maculatus is more likely the survival and reproductive success of adult E. suratensis which in turn provide eggs and eleutheroembryos for the egg-young predatory habit of E. maculatus. Predation is lessened by age-specific crypticity of E. suratensis. E. maculatus displays a unique behavior during its parental cycle where both parents actively defend their young until they are nearly sexually mature and almost the size of the parents. Adult E. suratensis engage in altruistic multiple parental care where several adults care for a single brood that presumably were spawned by only two of the adults. Such behavior has not been reported previously for fish.

Visual pigment was extracted from a fresh water toleost,Etroplus suratensis and the optical density measured over a range of 300–650 nm. The absorption spectrum indicates the λmax at 550 nm and a small hump at 530 nm. Through partial bleaching at 630 nm, it was confirmed that the fish possesses a mixture of 2 visual pigments: the one with the λmax at 550 nm predominating over the other.