Acute tolerance and histopathological effects of ammonia on juvenile maroon clownfish premnas biaculeatus (block 1790)

Abstract

This study evaluated the median lethal concentra-tion values (LC50) and the histopathological effectsof un-ionized ammonia (NH3--N) on juvenile mar-oon clownfishPremnas biaculeatus. After 96 h ofexposure to different concentrations of ammonia,juveniles were sampled for histopathological evalu-ation. The 24 and 96 h LC50 values of NH3-Ndetermined were 1.68 and 0.89 mg L1respec-tively. Maroon clownfish exposed to differentammonia concentrations displayed histopathologi-cal alterations in the gills, kidney, liver and brain.Gill tissue damage included lamellar hyperplasia,lamellar shorting and hyperplasia and hypertro-phy of mucous cells. The kidney showed hyper-anaemia, enlarged sinusoids within an apparentlydecreased amount of haematopoietic tissue,oedema on tubular cells and tubular necrosis, andan enlarged Bowman’s capsule. The liver presenteddilatation of hepatic sinusoids, fatty deposition inhepatocytes and Mallory bodies. Examination ofthe brain revealed a proliferation of glial cells, andthe Virchow-Robin space indicated a severe peri-vascular oedema and signs of neuronal sufferingwith satellitosis. The results of this study indicatethat juvenile maroon clownfish are relativelysensitive to ammonia and particular attentionmust be given to this toxic compound in culturesystems.