10.22376/ijpbs.2019.10.1.p1-12 Volume 3 Issue 1 2012 (January - March) Present paper deals with the impact of distillery effluent of GIDA, Gorakhpur, at iis various concentration levels (5%, 10%, & 20%) on the nucleic acid (DNA and RNA) and protein concentrations during different phases of testicular cycle (prespawning, spawning and post spawning) of a tropical freshwater perch, Colisa fasciatus (Bl. & Schn.). Observations reveal that 5% and 10% effluent concentration could produce least significant alterations in the nucleic acids and protein concentration during any phase of testicular cycle. However, 20% effluent concentration brought significant alterations in nucleic acid as well as protein content in all the phases of testicular cycle of lessThan i greaterThan Colisa fasciatus. lessThan /i greaterThan It was more pronounced during the spawning phase. Anuradha Shukla And J.P. Shukla Distillery effluent, DNA, RNA, Protein, Phases of Testicular Cycle, Colisa fasciatus, 532-537