Abstract: The present study deals with the ichthyofaunal diversity of Halali Reservoir in Vidisha district, Madhya Pradesh. Ichthyofaunal studies were undertaken during February – September 2011. The results of present investigation reveal the occurrence of 29 fish species belonging to 7 orders, 10 families and 15 genera. The order Cypriniformes was found dominant (18 species) followed by Ophiocephaliformes (4 species), Clupeiformes and Mastacembeleformes (2 species) and Beloniformes, Perciformes and Siluriformes (1 species) each. The range of different physico-chemical parameters were observed such as air temperature 24oC - 37oC; water temperature 21oC - 28oC; TDS 120 – 150 ppm; Conductivity 245 – 280 µS/cm; pH 7.1 – 9; Free CO2 nil - 8.4 mg/l; Dissolved Oxygen 6 – 9.8 mg/l; Phenolphthalein alkalinity nil – 40.02 mg/l; Total alkalinity 56 – 236 mg/l; Total hardness 50 – 120 mg/l; Chloride 57.99 – 96.99 mg/l; Orthophosphate 0.122 – 1.06 mg/l and Nitrate 0.16 – 1.12 mg/l.