Histopathological Changes In Gills Research Articles

Lanthanum exerts acute toxicity and histopathological changes in gill and liver tissue of rare minnow (Gobiocypris rarus).

We evaluated the acute toxicity effects of lanthanum (La(III)) on gill and liver of rare minnow (Gobiocypris rarus). The median lethal concentration of La (III) at 96 h was 1.92 mg L-1. Rare minnow were reared in freshwater and exposed to 0.04, 0.08, 0.16, 0.32 and 0.80 mg L-1 La (III) for 21 d. Gill and liver samples were analyzed by light microscopy. The main histopathological changes induced by La (III) in gills were epithelial lifting, filamentary epithelial proliferation,edema, lamellar fusion, desquamation, and necrosis. Histopathological changes induced by La (III) in the liver included dilation of sinusoids, focal congestion, pyknotic nuclei, karyohexis and karyolysis, vacuolar degeneration, and numerous necrosis areas. Hypsometric analysis indicated significant changes in the measures of gill dimensions (average length, width, area), suggesting metabolic disturbance (gas exchange) upon La (III) exposure. The result showed that La (III) severely affects fish gill and liver.

Gender-specific histopathological response in guppies Poecilia reticulata exposed to glyphosate or its metabolite aminomethylphosphonic acid.

Ecotoxicity of glyphosate (GLY) and its metabolite aminomethylphosphonic acid (AMPA) was investigated in guppies, Poecilia reticulata. We tested the effects of these chemicals on the gills and liver of both male and female guppies using qualitative and quantitative histopathological analyses associated with histopathological condition indexes. Both genders showed similar median lethal concentration (LC50 ) at 96 h for GLY (68.78 and 70.87 mg l-1 ) and AMPA (180 and 164.32 mg l-1 ). However, the histopathological assessment of both fish organs exposed to sublethal concentrations of GLY (35 mg l-1 ) and AMPA (82 mg l-1 ) for 96 h showed a tissue- and gender-specific histopathological response. In both exposure assays, fish presented mainly progressive changes, such as proliferation of the interlamellar epithelium, partial and total fusion of secondary lamellae. The liver showed mainly regressive changes, such as steatosis, pyknotic nuclei and high distribution of collagen fibers. Unusually large hepatocytes as degenerated cells were also detected. Histopathological changes in gills were similar for the males and females, but the liver response was different between the genders. The hepatic inflammatory changes were more common in males. The increase in the area of hepatocyte vacuoles is gender dependent with higher values in the male compared to the female guppies exposed to GLY and AMPA. Multiparametric analysis indicated that the male guppies are more sensitive than females, particularly in the presence of AMPA. Our study shows that the histopathological assessment associated with gender-specific response can be successfully used in ecotoxicological assessment of GLY and the metabolite AMPA. Copyright © 2017 John Wiley & Sons, Ltd.

Gill Histopathological Effects of PAHs on Adult Pearl Oyster, <i>Pinctada radiata</i> at Al-Khiran Coast in Kuwait

The hazardous effect of water pollution on the histopathology of gill organ of the pearl oyster, Pinctada radiata was studied with respect to polycyclic aromatic hydrocarbon contamination in Al-Khiran coast at Kuwait. Thirty oyster samples from each site, site one where dead oysters were located, site two which is two kilometers away from site one and the control site which is ten kilometers away from site one were collected from Al-Khiran area where a massive number of dead oysters were reported. The gills of oysters were immediately removed and transferred to Bouin’s solution for fixation and then processed for sectioning, staining and mounting and gill tissues were ready for examination. Histopathological changes in gills of oysters exposed to polycyclic aromatic hydrocarbons in site one and site two included necrosis and edemas of branchial lamellae, complete degeneration of gill filaments, loss of regular shape and haemolysis, and inflammation. Gill tissues of oysters from the control site had normal appearance. The study showed a clear evidence that PAHs caused severe histopathological changes in gills of pearl oyster Pinctada radiata.

Histopathological Changes in Gills, Liver, and Kidney Tissues of Bighead Carp (Aristichthys nobilis) Due to the Effects of Acute High-Temperature Stress

Histopathological evaluation of fish tissues is a reliable method for detecting exposure to toxins and other environmental perturbations that cause stress or even death. This study aimed to evaluate the histopathological changes that might occur in the internal organs of Bighead carp (Aristichthys nobilis) following acute high-temperature stress. By examining tissues sampled at various timepoints after heat shock (3, 6, 12, and 24 hours), we observed severe anatomical alterations in three vital organs. In the gills, epithelial lifting and edema, blood congestion, primary lamellae thickening, and secondary lamellae curling, shortening, and fusion were evident. In the liver, karyolysis, necrosis, hyperemia, dilation of sinusoids, nuclear hypertrophy, and congestion of the central vein were observed. Kidneys displayed dilation of the Bowman’s space, an increase in the diameter of the renal tubules, hyperemia, shrinkage and congestion of the glomeruli, and tubular necrosis. Cumultaively, this analysis indicates that Bighead carp are highly susceptible to changes in environmental temperature, and rapid intervention is required in response to temperature disruptions during aquaculture. This study will therefore encourage aquaculturists to closely monitor culture temperatures for this economically important species of fish.

Histopathological Changes in Gills, Liver, and Kidney Tissues of Bighead Carp (Aristichthys nobilis) Due to the Effects of Acute High-Temperature Stress

Histopathological evaluation of fish tissues is a reliable method for detecting exposure to toxins and other environmental perturbations that cause stress or even death. This study aimed to evaluate the histopathological changes that might occur in the internal organs of Bighead carp (Aristichthys nobilis) following acute high-temperature stress. By examining tissues sampled at various timepoints after heat shock (3, 6, 12, and 24 hours), we observed severe anatomical alterations in three vital organs. In the gills, epithelial lifting and edema, blood congestion, primary lamellae thickening, and secondary lamellae curling, shortening, and fusion were evident. In the liver, karyolysis, necrosis, hyperemia, dilation of sinusoids, nuclear hypertrophy, and congestion of the central vein were observed. Kidneys displayed dilation of the Bowman’s space, an increase in the diameter of the renal tubules, hyperemia, shrinkage and congestion of the glomeruli, and tubular necrosis. Cumultaively, this analysis indicates that Bighead carp are highly susceptible to changes in environmental temperature, and rapid intervention is required in response to temperature disruptions during aquaculture. This study will therefore encourage aquaculturists to closely monitor culture temperatures for this economically important species of fish.

Histopathological Changes in Gills and Liver of African Catfish <i>Clarias gariepinus</i> Exposed to Methanolic Leaf Extract of <i>Khaya senegalensis</i> (African Mahogany)

The histopathological changes in gills and liver of Clarias gariepinus juveniles exposed to methanolic leaf extract of Khaya senegalensis were investigated. Methanolic leaf extract of K. senegalensis was obtained, dissolved and dispersed into twelve (12) glass experimental aquaria with dimension 30.50 x 30.50 x 44.25 cm each containing 20 L of dechlorinated water of ten (10) fish per aquarium at different concentrations and three replicates. Juvenile C. gariepinus of weight 18.47±3.06 g and standard length 10.9±2.7 cm were introduced in each aquarium and exposed for 96 h period as endpoint toxicity. Three of these fish juveniles were randomly sampled from the control and each treatment aquarium and dissected to remove the gills and liver for histopathological analysis. The results showed a significant (P<0.05) association between the concentration of leaf extract K. senegalensis and mortality in exposed fish. The lethal concentration of the extract was 199.69 mgL-1. The extract caused severe gills alteration, epithelial hyperplasia, cellular infiltration and mild fatty desquamation in the gills and high congestion, necrosis and desquamation of the liver. This plant is to be regarded as a piscicidal toxicant and should be considered unwanted alongside aquatic ecosystem. Keywords: Toxicity, deformities, histopathology, Khaya senegalensis, Clarias gariepinus

Histopathological and biochemical effects of cyanobacterial cells containing microcystin‐LR on Tilapia fish

AbstractBlooms of Microcystis aeruginosa, commonly observed in many lakes of Tamil Nadu, produce the cyanobacterial toxin Microcystin, which has tumor promoting property in fish. Strains of Microcystis aeruginosa species have the same morphology but may vary in their toxicity. In the present study, Microcystin produced by Microcystis aeruginosa from Thenneri lake in Kancheepuram district of Tamil Nadu, was isolated and characterized by high‐performance liquid chromatography and electron spray ionization mass spectroscopy. Based on spectroscopic results the toxin was identified as Microcystin‐LR. Toxicogenicity was evident from the alteration in the activity of antioxidant enzymes [Glutathione S‐transferase and Catalase] and increase of protein and lipid peroxidation contents in Oreochromis niloticus, a fresh water fish species, after controlled exposure to Microcystis aeruginosa cells. Toxicity was further confirmed by histopathological changes in gill, liver and intestine of exposed fish.

Histopathological study of gill, kidney and liver of Persian Sturgeon (Acipenser persicus Borodin, 1897) and Stellate (Acipenser stellatus Pallas, 1811) exposed to sublethal concentration of un-ionised ammonia UAN.

This study was carried out to investigate the histopathological changes of gill, kidney and liver of Persian Sturgeon and Stellate in response to various sublethal concentration of ammonia. The sublethal doses were determined after a lethal pre-test and then the experiment was done in six treatments with three replicates for both species. In Persian sturgeon, the treatments were including 5, 7, 9.7, 13.2, 18 and 25mg/l ammonia. In stellate, the concentrations of 5, 6.23, 7.76, 9.66, 12.04 and 15mg/l ammonia were considered as treatments. Also, one group without ammonia was considered as control for each experiment. The histopathological investigations were done after 96h exposure. According to our observations, a range of histopathological alternations were found in gill, liver and kidney of both examined fish. The alternations of gill tissue were lamellar necrosis, hyperplasia, lamellar adhesion, haemorrhage, swelling of gill lamellae. Severity of these alternations was dose-dependent and was significantly higher in Persian sturgeon than in stellate. The degree of histopathological alternations of liver did not show a regular pattern between treatments in both species. These alternations were hyperemia, bile record, cell necrosis, cell atrophy, fatty degeneration and cloudy swelling. The signs of kidney alternations intensified with increasing of ammonia concentration in both species. The signs such as hyperemia, vision tissue degeneration, cell necrosis, dilatation of Bowman's space. In conclusion, our results showed that ammonia in concentration of more than 5mg/l have more adverse impacts on gill, liver and kidney tissues.

Histopathological Changes in Tissues of Danio rerio Exposed to Sub Lethal Concentration of Combination Pesticide

The objective of this study is to investigate in detail the histopathological changes in gill, liver, brain, spinal cord, ovary and kidney of zebra fish exposed to combination pesticide. Twenty one days semi static exposure to sublethal concentration of 8.4 and 4.2 μg/L of Chloropyrifos 50% + Cypermethrin 5% EC was conducted and it was followed with a reversal period of 7 days without pesticide in the exposure water. Three fish were collected from control and treatment group periodically. Whole body fixation of zebra fish as per OECD guidance document 123 was adopted for obtaining the histopathology sections. Structural damages of gill observed were of inflammatory cell infiltration, minimal congestion in primary lamellae, fusion of secondary lamellae, diffused epithelial hyperplasia and multifoci mucus cell hyperplasia. In liver, moderate, diffused to severe cytoplasmic vacuolation, diffused minimal to mild sinusoidal congestion, steatosis, pyknotic, karyorrhectic nuclei with complete dissolution of necrotic hepatocytes was observed. Minimal focal tubular degeneration was observed in kidney. Minimal to mild multifocal follicular atresia was observed in the ovary. In spinal cord neuronal cell degeneration, cytoplasmic vacuolation and enlargement of neuronal body was observed. In brain, mild to moderate demyelination in the neurophil and mild necrotic changes observed in the cerebrum. Some of the lesions were less pronounced after recuperation period. Pesticide in exposure water was analyzed using Agilent QQQ GC-MS/MS equipped with Election Impact Ionization mode. Limit of detection and quantification was 1 μg/L with a Correlation Co-efficient (CC) of 0.999. The recovery of active content of Chlorpyrifos for 4.2 and 8.4 μg/L at 0 hour was 88.1%, 90.3% and at 48 hour was 83.48%, 85.70%, respectively. Similarly, Cypermethrin active content recovered at 0 hour for 4.2 and 8.4 μg/L was 78.74%, 86.24% and at 48 hour was 57.85%, 62.09%, respectively. Further, this is the first study to report pathological findings in Zebrafish exposed to a combination pesticide formulation. The histopathological finding of this investigation reveals the potential toxic hazard from exposure to sub lethal level of the combination pesticide. Few literatures have reported on the mixture toxicity of pesticides and this research work throws light on histopathological lesions of Zebrafish. Further, this is the first study to report spinal lesions in fish due to pesticide exposure. Pesticides usage in pest management or in agriculture practice should be applied safely to prevent pollution and contamination.

Pesticides Toxicity in fish with particular reference to Insecticides

Aquatic Toxicology is the study of the effects of environmental pollutants on aquatic organisms, such as pesticides especially the insecticides, on the health of fish or other aquatic organisms. Pesticides are substances used to control pests, including insects, aquatic weeds, plant diseases, and Aquatic snails that carry the cause of schistosomiasis. Pesticides have been found to be highly toxic not only to fish but also to the other organisms, which constitute the food chain. Pesticides in general, are used very extensively in agriculture, forestry, public health and in veterinary practices. Pesticides are categorized according to their target use. The three major pesticides are herbicides (weed control), insecticides (insect control), and fungicides (Mycotic control), but the more acute toxicity are insecticides. Since fishes are important sources of proteins and lipids for humans and domestic animals, so health of fishes is very important for human beings. Insecticides are the chemicals used to control insects by killing or preventing them from engaging in unwanted behaviors or destructive. The contamination of surface waters by insecticides is known to have ill effects on the growth, survival and reproduction of aquatic animals. Different concentrations of insecticides are present in many types of waste water and numerous studies have found them to be toxic to aquatic organisms, especially fish species. Application of insecticides used for control a wide variety of insectivorous and herbaceous pests which would otherwise diminish the quantity and quality of food production. Unfortunately, in spite of its advantages, chemistry has great disadvantages as well as insecticides are threatening the long-term survival of major ecosystems by disruption of ecological relationships between organisms and loss of biodiversity. The major Chemical groups of insecticides that are usually applied Organophosphate, Carbamates, Organochlorine, Pyrethroids, and Necotenoides. The insecticidal residues which contaminate the water are mainly due to the intensive agriculture combined with surface runoff and surface drainage, usually within a few weeks after application. Insecticides lead to decrease rate of growth, reproductive disorders. Also, cause spinal deformities and histopathological changes in gills, liver, hematopoietic tissue such as spleen, head of the kidney and renal tubules, endocrine tissues as well as brain, neurological, behavioral disorder and genetic defect are other biological indicators of exposure to insecticides. Fishes are particularly sensitive to the environmental contamination of water. Hence, these pollutants such as insecticides may significantly damage certain physiology and biochemical processes that different kinds of insecticides can cause serious impairment to physiological and health status of fishes. Aquaculture is one of the fastest growing food producing sectors, supplying approximately 40% of the world's fish food. Besides such benefit to the society, the industry does have its problems. Potentially harmful substances are often release into the aquatic environment. When is the launch of large quantities of pollutants there might be an immediate impact as measured by mortality the sudden large-scale aquaculture, for example, fish kills caused by pollution of water ways with agricultural pesticides. Lower levels of discharge may result in accumulation of pollutants in aquatic organisms. The final results, which may occur after a long period has passed pollutants through the environment, and include immune suppression, low metabolism, and damage to the gills and epithelia. This review presents further information concerning effects (Acute, sub chronic and chronic) of the different concentrations of pesticides (including insecticides) on various aspects of fish's biology and physiology. Also, depicts behavior, genetic and immune system of fish. The information given in this review facilitates the evaluation of potential toxic hazard resulting from exposure to different levels of these compounds. Data could be acquired useful in environmental risk assessment of freshwater organisms and marine. The histopathological changes in fish tissues used as a biological indicator for pollution with pesticides with special reference to insecticides. Finally, Protection of wildlife and water quality is possible when rationalize the use of pesticides. Also, when Pesticides must choosing judiciously and are used in combination with other pest management tools, and applied safely, the surface water pollution and contamination of our aquatic life could be avoided.

Assessment of oxidative damage to DNA, transcriptional expression of key genes, lipid peroxidation and histopathological changes in carp Cyprinus carpio L. following exposure to chronic hypoxic and subsequent recovery in normoxic conditions.

In fish, a complex set of mechanisms deal with environmental stresses including hypoxia. In order to probe the hypothesis that hypoxia-induced stress could be manifested in varieties of pathways, a model species, mirror carp (Cyprinus carpio), were chronically exposed to hypoxic condition (dissolved oxygen level: 1.80 ± 0.6 mg/l) for 21 days and subsequently allowed to recover under normoxic condition (dissolved oxygen level: 8.2 ± 0.5 mg/l) for 7 days. At the end of these exposure periods, an integrated approach was applied to evaluate several endpoints at different levels of biological organisation. These included determination of (i) oxidative damage to DNA in erythrocytes (using modified comet assay), (ii) lipid peroxidation in liver samples by measuring the malondialdehyde production using the 2-thiobarbituric acid [i.e. thiobarbituric acid reactive substances (TBARS) assay] and (iii) histopathological changes in gills. In addition, transcriptional expression of hypoxia-inducible factor 1 α (HIF-1α) and genes involved in the repair of oxidative damage to DNA (i.e. ogg1) and base excision repair (i.e. xrcc1) using reverse transcription polymerase chain reaction in liver samples were also determined. The results suggested significantly enhanced expression of these genes in response to hypoxia compared to concurrent normoxic controls. While the expression of HIF-1α reverted to control values within 7 days exposure to normoxic condition (P < 0.05), the transcriptional expression of the two genes involved in DNA repair process remained significantly high under the recovery period, which complemented the induction of oxidative damage to DNA. Hypoxic groups showed significantly increased values for TBARS level (~2-fold) and histopathological changes in gill tissues compared to both normoxic and recovery groups. Overall, oxidative damage to DNA determined by modified comet assay reflected the observed biological responses in other tissues of the fish. Along with other parameters, this integrated experimental design further strengthens the applications of the comet assay as an important technique to assess stress-induced DNA damage in ecotoxicological studies.

Integrating multiple fish biomarkers and risk assessment as indicators of metal pollution along the Red Sea coast of Hodeida, Yemen Republic

The marine environment of the Red Sea coast of Yemen Republic is subjected to increasing anthropogenic activities. The present field study assesses the impacts of metal pollutants on two common marine fish species; Pomadasys hasta and Lutjanus russellii collected from a reference site in comparison to two polluted sites along the Red Sea coast of Hodeida, Yemen Republic. Concentrations of heavy metals (Fe, Cu, Zn, Cd and Pb) in fish vital organs, metal pollution index (MPI), indicative biochemical parameters of liver functions (alanine aminotransferase [ALT] and aspartate aminotransferase [AST]) and kidney functions (urea and creatinine) as well as histopathological changes in gills, liver and kidney of both fish species are integrated as biomarkers of metal pollution. These biomarkers showed species-specific and/or site-specific response. The hazard index (HI) was used as an indicator of human health risks associated with fish consumption. The detected low HI values in most cases doesn’t neglect the fact that the cumulative risk effects for metals together give an alarming sign and that the health of fish consumers is endangered around polluted sites. The levels of ALT, AST and urea in plasma of both fish species collected from the polluted sites showed significant increase in comparison to those of reference site. Histopathological alterations and evident damage were observed in tissues of fish collected from the polluted sites. The investigated set of biomarkers proved to be efficient and reliable in biomonitoring the pollution status along different pollution gradients.

Use of histopathology and elemental accumulation in different organs of two benthophagous fish species as indicators of river pollution

The bottom feeding fish species have a good potential to be used for assessments of pollution, as they are under pressure from pollutants from both water and sediments. In this study, the level of similarity of histopathological responses to pollution in gills and liver between barbel (Barbus barbus) and sterlet (Acipenser ruthenus) from the Danube River was assessed, and compared with elemental concentrations in their gills, liver, and muscle. Results indicate that the detected metal concentrations were likely cause of different tissue responses in gills and liver of the two investigated fish species. Statistical analysis indicated a clear differentiation of the two species based on elemental concentrations and the level of histopathological changes in gills and liver. Metal concentrations exceeded maximum acceptable concentrations in a number of analyzed specimens, which indicates the importance of this type of monitoring. Results indicate that barbel is a better indicator for specific, rather narrow sites, whereas sterlet is a better indicator of larger (longer) water current segments. Obtained information could be of importance for both scientists and fishery and water management authorities working on the development of water monitoring programs.

Lead- and cadmium-induced histopathological changes in gill, kidney and liver tissue of freshwater climbing perch Anabas testudineus (Bloch, 1792)

The objective of this study was to examine the toxicological effect of two major heavy metal pollutants, lead chloride (PbCl2) and cadmium chloride (CdCl2), in the freshwater climbing perch, Anabas testudineus. Fish were exposed to 1.0 and 2.0 mg/L both metals and histopathological changes in gill, kidney and liver tissues were studied. Major changes observed in gill tissue were epithelial lifting, proliferation of epithelial cells, fusion of secondary lamellae, hyperplasia and hypertrophy of mucous cells, and necrosis of epithelial cells. Cell necrosis, degenerated kidney tubules, congestion, lymphocytic infiltration and vacuolation were the major abnormalities observed in kidney tissue. The most conspicuous changes in liver were darker nucleoli, irregularly shaped hepatocytes with dilated blood capillaries, and focal as well as single necrosis. Fish specimens exposed to PbCl2 exhibited pronounced changes in all tissues examined compared with those exposed to CdCl2. It is evident from this study that heavy metals can cause significant histopathological changes in fish tissue.

Hematological and histopathological changes in silver catfish Rhamdia quelen (Siluriformes) exposed to clomazone herbicide in the Madre River, Santa Catarina State, Southern Brazil

This study evaluated the influence of the clomazone herbicide (2-[(2-chlorophenyl)methyl]-4,4-dimethyl-3-isoxazolidinone) contamination on the hematological parameters and histological changes in gills and liver of silver catfish (Rhamdia quelen) from Madre River, Santa Catarina State, Southern Brazil. Fish were collected between March 2010 and January 2012 at two different sites of the Madre River, one site receiving residual water (contaminated site) from rice culture (n = 49) and another that do not receive residual water (reference site) (n = 48). The herbicide clomazone analysis detected 3.40 ± 1.70 μg/L in the contaminated site and 1.1 ± 0.33 μg/L in the reference site. Fish from contaminated site showed increased (P < 0.05) number of monocytes suggesting the possible defense response as a result of chronic exposure to clomazone. On the other hand, no difference was found in the hematocrit percentage, red blood cell count, total thrombocyte number, white blood cell count, lymphocytes, and neutrophils number. Fish from both sites showed histopathological changes in gills and liver, possibly caused by chronic exposure to contamination. The influence of herbicide sub doses on fish health is also discussed.

Histopathological changes of gill, liver and kidney in Caspian kutum exposed to Linear Alkylbenzene Sulfonate

The histopathological effects of Linear Alkylbenzene Sulfonate on the gill, liver and kidney tissues of the Caspian kutum, Rutilus frisii kutum were studied. The fish were exposed to three sublethal concentrations of anionic detergent, Linear Alkylbenzene Sulfonate (LAS) for short term intervals (192 h). Gill, liver and kidney samples were collected after 192 h of exposure to LAS and lesions were analyzed by light microscopy. The histological changes to gills were edema, fusion of lamellae and lamellar aneurism. Some alterations like reduction of the interstitial haematopoietic tissue, tubular shrinkage, degeneration in the epithelial cells of renal tubule and necrosis were observed in the kidney. In the liver tissue, hepatocyte degeneration, congestion and dilation of sinusoid and vacuolar degeneration were seen. It seems that sublethal concentration of LAS may affect sever changes to gill, kidney and liver of R. frisii kutum specimens that leads to malfunction of these organs which cause damage to health of the fish .

Gill tissue recovery after copper exposure in Carassius gibelio (Pisces: Cyprinidae)

Abstract We investigated the influence of copper in a long-time treatment with concentrations of 0.05 mg L−1 and 0.1 mg L−1 to track the histopathological changes in gills of Carassius gibelio, and to find at what extent they will recover after the effect of the copper concentrations stops. Treatment with copper lasted 21 days and the recovery time was of the same duration. The results of histological examination showed degenerative changes (resulting in thinner secondary lamellae and filamentary epithelium), and hyperplastic and hypertrophic changes (proliferation, vasodilatation, aneurysms, epithelial interstitial edema, and fusion) in gills under the influence of two concentrations. The degenerative changes have higher prevalence at low concentrations, while hyperplastic and hypertrophic ones — at high concentrations. After the period of recovery they remained the same, but the extent of expression on the surface of gill filaments changed. The long-time copper intoxication in low concentrations of copper affects gill structure, causing severe changes whose recovery is a slow process that requires a longer period of time.

Histopathological indicators: a useful fish health monitoring tool in common carp (Cyprinus carpio Linnaeus, 1758) culture

Abstract In order to evaluate the relationship between water quality in ponds and indices of histopathological changes occurring in the vital organs of the common carp (Cyprinus carpio L., 1758), two six-month field experiments were carried out using two different water supplies: from the nearby stream and a tube well. The fish were fed supplemental feed: raw cereals, pelleted and extruded compound feed. Histopathological analysis, alteration frequencies, and semi-quantitative scoring of the changes were used to assess the health status of the fish. Ponds supplied by stream water were characterized by higher water hardness, dissolved oxygen and pH values, while those supplied by the tube well had higher electroconductivity, total ammonium and orthophosphates content. Fish survival rate and habitat suitability index were lower in ponds supplied by stream water, while the weight gain did not differ between the two water supplies. The use of stream water resulted in a higher level of histopathological changes in gills and liver. Among the water quality parameters, pH level had the strongest influence on fish. Differences in water supply produced greater influence on the level of histopathological changes than the type of feed applied. Gills were the most sensitive organ, while the kidney was the least responsive.

Histopathological changes in the gill, liver and intestine of Heteropneustes fossilis (Bloch) treated with three dry seed extracts

Acute toxicity tests were carried out with aqueous and ethanolic extracts of three botanicals Lagerstroemia speciosa (L.) Pers, Dipterocarpus turbinatus Gaertn and Hevea brasiliensis (Willd. Ex Juss) on Heteropneustes fossilis (Bloch) under normal laboratory conditions. Extracts of L. speciosa were more potent than the extracts of D. turbinatus and H. brasiliensis. Histopathological changes in gill, liver and intestine of exposed fishes caused subtle cellular damages like disintegration of gill filaments and lamellae, degeneration of hepatocytes and blood vessels and necrosis of the intestinal epithelia. Different seed extracts showed histopathological variations in the different organs depending on the toxicity of the plant extracts. On the basis of histopathology, effectivity of the extract was in the order: Absolute ethyl alcohol &gt; 50% ethyl alcohol &gt; distilled water and the effectivity of the seed extracts on the studied organs was: L. speciosa &gt; D. turbinatus &gt; H. brasiliensis seed extracts. DOI: http://dx.doi.org/10.3329/jasbs.v38i2.15612 J. Asiat. Soc. Bangladesh, Sci. 38(2): 217-226, December 2012

Sublethal effect of nanosilver on the structure of gill of Caspian roach (Rutilus rutilus caspicus) fingerlings

Widespread use of nanosilver can be led the contamination of aquatic environment and impact on living organisms such as fishes. We investigated histopathological changes in the gills tissue of Caspian roach fingerlings after two weeks exposure to sublethal concentrations of nanosilver. Following one and two weeks exposure, necrosis, shortening of secondary lamellae, edema, destruction of epithelial lamella, shortening of secondary lamellae, epithelial lifting and curling of secondary lamellae were observed in gill tissues. This observation showed that exposure to sub-lethal concentrations of nanosilver is caused damages in the gill tissues of Caspian roach. The results demonstrated direct correlation of gill tissue damage and toxin exposure i.e. increasing nanosilver concentration is caused more tissue damage. Hence, histopathological changes of gill can considered as a proper indicator for nanosilver contamination of aquatic environments.