Biochemical study of some metabolic indicators of fish Mastacembelus mastacembelus (Banks & Solander, 1794) and its parasite tapeworm Senga mastacembeli

This study is the first global attempt to evaluate the influence of the parasitic tapeworm Senga mastacembeli on its fish host, Mastacembelus mastacembelus, using tissue biomolecules to bridge the informational void regarding this fish. Forty-six alive and mature fish were gathered from a fish market in Mosul, Iraq. We removed and extracted tapeworms from the fish’s intestine. Also, an extract of the liver and intestinal tissues of both infected and uninfected fish was made for estimation of proteins, carbohydrates, aspartate transaminase, alanine transaminase, alkaline phosphatase, and lactate dehydrogenase activities using colorimetric techniques. The findings at p ≥ 0.05 showed that the intestine of infected fish had concentrations of total proteins of 178.6 and carbohydrates of 122.1 mg/g wet weight that were significantly lower than those of uninfected fish, which had concentrations of 232.2 and 183.3 mg/g wet weight, respectively. On the other hand, the protein and carbohydrate concentrations of the tapeworm tissues were 106.9 and 94.5 mg/g wet weight, respectively, which were significantly lower than those of infected and uninfected fish. Regarding liver enzyme activities, the infected fish’s alanine transaminase and alkaline phosphatase, measuring 83.3 and 63.0 IU/L, respectively, were significantly lower than the uninfected fish’s 109.1 and 125.0 IU/ L, while the infected fish’s lactate dehydrogenase activity was higher at 223.6 IU/L compared to the uninfected fish’s 198.4 IU/L. However, the aspartate transaminase activity of infected and uninfected fish did not differ significantly. Furthermore, the most sensitive ratio to parasite infection was the aspartate transaminase/alkaline phosphatase, which was followed by the aspartate transaminase/alanine transaminase and lactate dehydrogenase/aspartate transaminase ratios. The study concludes that the studied biomolecules can be used as reliable biomarkers of the severity of fish infection with parasitic tapeworms.