This study investigated the effects of Aspergillus niger CSA35 pretreated-cassava (Manihot esculenta Crantz) peel feed (CPFG) on the body weight gain and some selected biochemical parameters of pigs. Cassava peels treated with biomass of A. niger CSA35 for a period of three weeks to initiate enzymatic digestion of peels were dried, ground and used in varying proportions to formulate pig rations in combination with other feed ingredients. Twenty 85–95 days old pigs (5.85±0.70 kg) were randomly divided into four experimental groups. Group 1 received 0% CPFG amidst other feed ingredients (control), while Groups 2, 3 and 4 received 40%, 60% and 100% CPFG respectively. At the end of the feeding trial (21 days), the animals were weighed and blood samples collected for biochemical analysis. Results showed that increasing the amount of the fungus-pretreated cassava peels in pig rations increased the protein, fat and carbohydrate contents of the experimental feeds. Conversely, the percentage fibre content was reduced. The weight gain of pigs fed the control diet was significantly (p< 0.05) lower than those fed with 60% CPFG and 100% CPFG but did not differ from those fed 40% CPFG. Serum calcium and albumin levels were observed to be significantly lower (p< 0.05) in control group than in treatment groups. The highest serum calcium level was, however, observed in 100% CPFG group. Activities of liver function enzymes and serum creatinine level of pigs fed the formulated diets did not significantly differ from those of control unlike their serum urea levels. It was concluded that pig feeds formulated with cassava peels pretreated with A. niger CSA35 enhanced feed’s nutritive value and metabolisable energy, boosted serum albumin and calcium levels in pigs, increased pigs body weight and are health-friendly since the feeds did not pose threat of liver damage in the pigs investigated.