This work investigated the effects of co-substrates (orange, mango, and pineapple wastes) and inoculums (chicken rumen), pH, and total solid (TS) content on animal waste (cow dung, pig dung, poultry droppings) for efficient and high biomethane production. The biomethanation experiments were carried out in five different 1.5 L anaerobic digesters and incubated for 10 weeks. The results showed that co-digestion of animal wastes with fruit wastes and inoculums (additives) increased biomethane yield and reduced the startup time for biomethane generation as compared to animal wastes alone. In addition, cumulative biomethane yield increased with increase in pH while it decreased with increase in TS content.