Increased acceptance of climate change induced by human activities and raising oil demand with unsecure deliverance compels the searching for alternative fuels. The problems with environmental degradation due to industrial wastes can be reduced by converting some of them into bio-oil. In the present work, the waste from fish processing industry is converted to bio-oil by catalytic cracking. Experiments were conducted in a direct injection diesel engine of 4.5 kW at 1500 rpm. The different test fuels of diesel, fish oil at 75 C, bio-oil UD (undistilled bio-oil), B20D80 (20% bio-oil in fossil diesel), B80D20 (80% bio-oil in fossil diesel) and neat bio-oil were tested to assess the suitability in diesel engines through combustion, emission and performance characteristics. Experimental results show that the brake thermal efficiency is marginally higher with neat bio-oil over other test fuels. It is lower with preheated fish oil and it is almost same for both bio-oil and bio-oil UD. NOx, HC, CO and PM emissions are higher with bio-oil UD compared to bio-oil. PM, CO and HC emissions are lower with bio-oil over diesel. NOx emissions are lower with bio-oil compared to bio-oil UD but it is still higher than diesel fuel. Addition of diesel with bio-oil reduces the NOx emissions marginally. Intensity of premixed combustion is strong with bio-oil. Ignition delay and combustion duration are reduced with bio-oil due to high cetane number and oxygen concentration. Bio-oil from waste fish fat by catalytic cracking can be used as a fuel for diesel engines and also the waste to energy may reduce the environmental and climate change issues due to industrial wastes. (C) 2012 Elsevier Ltd. All rights reserved.