Fish scales as indicators of water quality in rearing of a major carp, Labeo rohita
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Date
2018
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Punjab Agricultural University, Ludhiana
Abstract
The present study was undertaken with the objective to analyse the concentration of heavy metals in cycloid scales of major carp Labeo rohita (Hamilton, 1822), of two size groups (less than 40cm and above 40cm) collected seasonally (summer and winter) from three fish markets (Jagraon bridge, Sherpur market and Tajpur market) and private fish farm in Krodian village, Payal tehsil of district Ludhiana (Punjab). A significant rise (p<0.05) was observed in the heavy metals concentration of scales of fishes collected from market vis-a-vis control fish. Levels of chromium, copper, lead and zinc were higher than the permissible limits set by WHO/FAO (2011). A non-significant (p<0.05) difference was noticed in the heavy metal concentration of scales of fishes of two size groups (less than 40cm and above 40cm). A positive relation was observed between the fish size and the level of heavy metals in fish scales which might be due to higher pollution load in the market fishes collected from various sources. A significantly higher (p<0.05) accumulation of heavy metals in scales during summer season might be due to higher rate of evaporation of water source leading to higher concentration of heavy metals. Photographs of scales of fishes collected from market showed damaged radii, eroded circuli, broken focus, damaged tubercles and dispersed chromatophores. In addition, structural anomalies such as empty sockets, eroded surface, broken and removed lepidonts, distorted pattern of circuli, broken surface and tears in edges of the scales were observed using scanning electron microscopy (SEM).The elemental composition of fish scales collected from market studied using energy dispersive x-ray microanalysis (EDS) indicated the presence of heavy metals. The present study, therefore, indicated that scales on the fish are effective indicators of water quality in which the fish has been reared.
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