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Heavy metal contamination in aquatic ecosystems has become an emerging environmental issue. The stable physico-chemical properties of heavy metals could result in bioconcentration and bioaccumulation in different organs of freshwater fishes. The present study records the accumulation of Lead (Pb), Cadmium (Cd), Chromium (Cr), Copper (Cu) and Zinc (Zn) in the head, muscle and skin regions of seven fish species namely, Labeo rohita , Oreochromis mossambicus, Oreochromis niloticus, Etroplus suratensis , Heteropneustes fossilis , Oligolepsis acutipennis and Puntius dorsalis collected from Minnerya, Parakrama Samudraya and Kaudulla reservoirs in Polonnaruwa district, Sri Lanka. The results showed that both Pb and Cd accumulated in high concentrations in the head region compared to the skin and muscles of the fish samples. The highest amounts of Pb (22.44±5.48 mg/Kg) and Cd (4.98±0.86mg/Kg) were recorded from the head parts of the H. fossilis in Minneriya and O. niloticus in Kaudulla respectively, whereas the highest amount of Cr (30.87±4.51mg/Kg) was detected in head part of the O. acutipennis in Minneriya. The Cu concentration was the highest (2.92±0.001 mg/Kg) in head regions of H. fossilis from Minneriya. Zn was the most abundant heavy metal detected in the head, muscle and skin regions of fish in all three reservoirs. The highest amount of Zn (118.93±10.55mg/Kg) was detected in the head part of O . acutipennis from Minneriya. The Pb, Cd, Cr, Cu and Zn concentrations detected in the head part of popular edible freshwater species, O. mossambicus, O. niloticus and E. suratensis were higher than the provisional tolerable weekly intake (PTWI) of Pb (0.025 mg/Kg), Cd (0.007 mg/Kg), Cr (0.1 mg/Kg), Cu (3.5 mg/Kg) and Zn (7 mg/Kg) specified by the FAO/WHO. Therefore, long-term consumption of these fish species especially the head parts may lead to accumulation of these heavy metals in tissues and lead to chronic diseases which may risk the health of consumers especially in the north-central province of Sri Lanka.

Multi-biomarker approach is recognised as a complementary tool for environmental monitoring studies to better appraise how pollutants affect ecosystems. This study examined histological alterations in the liver tissues and nuclear abnormalities in the peripheral erythrocytes of two native fish species inhabiting the Kelani River (Etroplus suratensis and Dawkinsia singhala) as ‘effect biomarkers’ for assessing pollution impacts. Surface water and native fish were sampled from two polluted sites in the lower reach (Kaduwela and Mattakkuliya) and a less polluted site in the upper reach (Ruwanwella) of the river covering rainy and dry periods. Physico-chemical analyses of surface water confirmed an increasing trend of pollution towards the lower reach of the river. Significantly greater liver histopathologic condition indices and erythrocytic nuclear abnormality frequencies (p

The present study was carried out to assess the levels of eight metals viz. Pb, Cu, Cd, Ni, Cr, Mn, Hg and Zn in two species of food fish, Etroplus suratensis and Ambassis commersoni from Negombo estuary. The levels of Hg were analyzed by cold vapour atomic absorption spectrometry whereas the other metals were analyzed by flame/graphite furnace atomic absorption spectrometry. Total metal levels in muscle, gill and liver tissues of the fish showed a wide range. Accumulation of most metals in the tissues of the fish followed the increasing order, muscle < gills ≤ liver. Of the different metal levels detected in the fish, only the level of Cd in liver tissue of 6% of E. suratensis and 12% of A. commersoni exceeded the level specified for human consumption by European Union. Interspecies comparisons revealed that mean level of Zn in the muscle tissue of A. commersoni was two fold higher than that of E. suratensis. The levels of metals in the muscle tissue of both fish species were positively correlated with the body weight or body length of the fish. Based on the levels of Hg, Pb, and Cd in the fish, edible muscle of both fish species collected from the estuary was found to be safe for human consumption. However, heavy consumption of bigger size fish may pose a health risk to the consumers as there were strong positive correlations between body weight or body length and metal levels in muscle tissues of both species of fish.DOI: 10.4038/sljas.v13i0.2207Sri Lanka J. Aquat. Sci. 13 (2008): 63-81

Histopathological changes induced by ergasilid parasitic infections on the gills of economically important fish from Batticaloa lagoon were investigated from October 2003 to November 2004. Anabas sp, Ambassis gymnocephalus , Chanos chanos , Cirrhinus mrigala , Etroplus suratensis , E. maculatus , Hemirhamphus sp, Leiognathus splendens , Lutjanus sp, Mugil cephalus , Nematalosa nasus , Oreochromis mossambicus , Siganus lineatus , S. oramin , Tachysurus sp, Terapon jarbua and Triacanthus brevirostris were naturally infected with the ergasilids viz. Ergasilus sieboldi , E. parvitergum , and Dermoergasilus sp. Intensity of infection ranged from 0 to 30 ergasilids per host fish. Histopathological investigations of infected gills showed extensive tissue damage due to attachment and feeding of ergaslids. Ergasilus sp attached close to the base of the filaments near the gill arch and the pressure exerted by the parasite attached to the lateral margin of the gill filaments induced atrophy of the secondary lamellae. Tissue reactions included hyperplasia and mucous cell proliferation of the gill epithelium and damaged primary and secondary lamellae. In addition, considerably high numbers of eosinophilic granular cells and rodlet cells were noticed in the gills of the infected fish. Histopathological changes induced by the ergasilid infections would adversely affect the proper functioning of the gills of these host fish. Mass mortalities of the fish inhabiting Batticaloa lagoon which occurred during April and May 2004 may be attributed to the infection of the fish gills by these ergasilids. DOI: 10.4038/sljas.v12i0.2215 Sri Lanka J. Aquat. Sci. 12 (2007): 77-87

There are 55 species of fin fishes belonging to 33 families in the Bolgoda Lagoon, of which about 30 are commercially important. Sardinella melanura, Caranx sansun, Leognathus. sp, Mugil cephalus, Etroplus suratensis and Trachysurus cae/us are the dominant species. The mean annual fin fish production is 30 mt/year and it is on the decline.