Haematological, biochemical, enzymological and histological responses of Labeo rohita exposed to methyl orange dye solution treated with Oedogonium subplagiostomum AP1

The present investigation is an attempt to assess the impact of untreated methyl orange and Oedogonium subplagiostomum AP1 treated methyl orange dye solutions on Labeo rohita. The behavioural response, mortality, haematological (red blood corpuscles (RBC), packed cell volume (PCV), haemoglobin (Hb), white blood corpuscles (WBC), mean corpuscular volume (MCV), mean corpuscular haemoglobin (MCH) and mean corpuscular haemoglobin concentration (MCHC)), biochemical (plasma glucose and protein), enzymological (aspartate amino transaminases (AST) and alanine amino transaminases (ALT)) and histological examination (gills, liver and kidney) of Labeo rohita are exposed to untreated and treated methyl orange dye solutions were assessed on 7th day. The fish exposed to tap water and treated dye solution showed normal behavioural response whereas abnormal behaviour was noted in fish exposed to untreated dye solution. Similar trend was recorded in the mortality rate of the fishes. Fish exposed to untreated dye solution showed reduction in RBC, PCV, Hb, MCHC, plasma glucose and plasma protein, increased level of WBC, MCV and MCH and also alteration in AST and ALT thereby indicating the toxicity of the dye. No such reduction and alteration were observed in haematological, biochemical and enzymological levels of fishes exposed to tap water and treated dye solution indicating the non-toxic nature of the degraded metabolites of dye. Histological examination of fishes exposed to methyl orange dye revealed necrosis and haemorrhage in the gills and hepatocytes, congested and shrunken glomeruli in kidney thereby indicating the toxicity of the dye. The histoarchitecture of control and algae-treated fishes showed no structural changes indicating the non-toxic nature of the degraded metabolites of the dye. The results concluded that methyl orange dye solution treated with O. subplagiostomum AP1 can be explored for aquacultural purposes owing to its non-toxic nature.