This study aimed to evaluate the performance, apparent nutrient digestibility, nitrogen utilization and ruminal fluid parameters of West African Dwarf (WAD) does fed Pleurotus sajor caju (Blight) biodegraded water hyacinth (Eichhornia crassipes) and green Guinea grass based diets. The chemical composition of fungi treated water hyacinth (FTWH), performance, apparent nutrient digestibility, ruminal fluid parameters and nitrogen utilization by WAD does were determined. Thirty female WAD goats with an average weight of 8.92 kg were used for a feeding trial which lasted for 105 days. In a completely randomized design, six animals each were allotted to five experimental diets comprising of 0%, 30%, 45%, 60%, and 90% FTWH inclusion level (as fed basis). Parameters measured were: dry matter intake (DMI), daily weight gain (DWG), feed conversion ratio (FCR), apparent digestibility of dry matter and crude protein, nitrogen intake, nitrogen balance, nitrogen retention, pH, rumen ammonia nitrogen, total volatile acids and molar concentrations of acetate, propionate and butyrate. Results revealed that the dry matter of FTWH was 77.73 g/100g DM, the crude protein and neutral detergent fibre were 14.38 g/100g DM and 60.20 g/100g DM respectively. Significant variations (P = 0.05) occurred in the DMI, DWG and FCR. They ranged from 342.12 - 368.62 g.d-1; 29.52 - 48.67 g and 11. 31 - 7.56 in does fed 0% and 90% FTWH inclusion level respectively. The same trend was observed for digestibility of dry matter, crude protein, crude fibre, ether extract, ash and neutral detergent fibre digestibility. The values ranged from 70.14 - 74.33; 79.83 - 83.15; 80.02 - 83.67; 79.83 - 88.65; 71.22 - 72.26 and 80.26 - 86.13% respectively. The nitrogen balance and retention also differed significantly (P = 0.05). They ranged from 4.00 - 4.70 g.d-1 and 62.50 - 66.94% in does that consumed 0% and 90% FTWH respectively. Treatment effect on pH, TVFAs and molar concentration of acetate, propionate and butyrate was significant (P = 0.05). They ranged from 6.15 - 6.31; 55.23 - 61.15mM/100ml and 11.23 -21.41; 30.41 - 41.33; 7.31-10.15 mM/100ml respectively. Ammonia nitrogen for all treatments was similar, but increased as the level of inclusion of FTWH increased. It can be concluded that inclusion of Pleurotus sajor caju biodegraded water hyacinth into the diets of does significantly improved performance, digestibility of nutrients, nitrogen utilization and ruminal fluid parameters. [ABSTRACT FROM AUTHOR]