Polycyclic aromatic hydrocarbons (PAHs) are pollutants released to the environment through natural and anthropogenic activities. PAHs if not being treated properly, are able to be transformed to various derivatives (daughters). There are possibilities that both PAHs and their daughter products to be toxic to environment and human. In this study, samples from influent of a water treatment plant (WTP) and effluent of sewage treatment plant (STP) were obtained to investigate presence of PAHs and their derivatives. Analysis of samples were conducted using Gas Chromatography Mass Spectrometry (GC/MS) and conversion formulation of the identified PAHs were found out. Furthermore, toxicity study carried out using guppy (Poecilia reticulate) to establish toxicity intensity of PAHs parents and daughters. The experiments were performed with three replicates using a total of 100 guppies for all definite tests through steady state method of acute toxicity test and mortality rates were investigated in 24, 48, 72 and 96 hours. Results indicated that phthalic acid and benzoic acid are significant compounds in both sampling points. Phthalic acid was found to be derived from Chrysene and Naphthalene whereas benzoic acid resulted from degradation of Fluoranthene. Mortality rates were 20 and 10, in WTP influent and STP effluent, respectively. No mortality was observed in control tank which indicated accuracy of toxicity test. Although, the pollution levels in both samples did not produce 50 mortality, the findings could indicate the conditions affecting fish populations in prolonged duration. © 2016 The Authors.