Effects of iodized salt on the histopathology of the gills and liver in Rhamdia quelen and Metynnis maculatus

Abstract

Table salt has been used as a reference substance in toxicological studies on fish and as an antiparasitic agent in aquaculture. The objectives of this work were to evaluate the sensitivity of Rhamdia quelen and Metynnis maculatus to iodized salt and to assess the possible changes in the gills and liver resulting from subchronic exposure of fish to this compound. The iodized salt toxicity levels after 96 h of exposure were 11.4 and 10.8 g L−1 for R. quelen and M. maculatus. None of the observed changes in the livers of the studied fish could be unequivocally correlated with salt exposure. In turn, it could not be entirely ruled out that the changes found in the gills, including epithelial lifting, oedema formation and vascular congestion, were caused by exposure of fish to salt.

Toxicity, physiological, histopathological, handling, growth and antiparasitic effects of the sodium chloride (salt) in the freshwater fish aquaculture

“…In ponds of Ictulurus punctatus maintained at three salinities (0.0025, 0.00125 and 0.025 g L −1 ), the snail densities in water at 0.025 g L −1 were lower than in the other treatments and no trematode infection was noted among snails or I. punctatus (Venable et al, 2000). Zeni et al (2017) reported reduction in I. multifiliis in Metynis maculatus exposed to 9-13.0 g L −1 of NaCl when compared with the control salinity. This result was not observed in R. quelen.…”

“…The acute toxicity of NaCl has been determined for some freshwater fish species (Table 1). Toxic effects of NaCl include mortality, which is directly proportional to the concentration because the tolerance to this chemical varies among fish depending on the species, temperature and other environmental conditions (Al-Dahaman & Atti, 1977;Burgdorf-Moisuk et al, 2011;Fontaínhas-Fernandes et al, 2000;Ghosh & Pal, 1969;Grizzle & Mauldin II, 1995;Hoque et al, 2020;Piazza et al, 2006;Zeni et al, 2017).…”

“…Clinical signs of NaCl toxicity include mortality, alteration in eye colour, erratic swimming, hyperactivity, increased opercular activity, jumping out of the test media, spasms, convulsions, swimming more actively, loss of equilibrium and swimming at the surface of water to obtain oxygen and oedema (Alderman et al, 1976;Al-Daham & Bhatti, 1977;Andrade et al, 2005;Akther et al, 2009;Al-Taee & Al-Hamdani, 2014;Burgdorf-Moisuk et al, 2011;Brion et al, 2013;Dewi et al, 2018;Demska-Zakęs et al, 2021;Mubarik et al, 2018;Parween et al, 2015;Velasco-Santamaría & Cruz-Casallas, 2008;Zeni et al,. 2017).…”