Effect of Parthenium Extract on the Metabolism of Young Colisa Fasciatus (BL. and SCHN.) (Pisces,Perciformes)

Parthenium hysterophorus seed extract possesses the potentiality to alter the fish metabolism. Lower concentrations (sublethal) of the seed extract stimulate the respiratory muscles, resulting in an increased rate of O₂ uptake, whereas higher concentrations (lethal) exhibit a neuro-toxic effect causing paralysis of the respiratory muscles manifested by a decreased rate of O₂ uptake, cessation of the respiratory pumps and casualty by asphyxiation. The seed extract also inhibits the activity of the enzymes SDH and carbonic anhydrase at the gas exchange sites. The log/log plotting of the O₂ uptake (mg/h) and the exposure period (2, 6, 12, 24, 72 and 168 h) showed slope values of 0.0744, 0.0778, 0.0322 and 0.0164, respectively, in four concentrations (10, 20, 25 and 30 %) of Parthenium extract.