The aim of this study was to determine the effects of herbal additives on growth performance and disease resistance during first-feeding of Oreochromis mossambicus fry. Four isonitrogenous (40% crude protein) and isocaloric (18.7 kJ/g) diets were formulated containing 0% (control) or 1.0% thyme (Thymus vulgaris), rosemary (Rosmarinus officinalis), or fenugreek (Trigonella foenum graecum). Fish were stocked at 36 fry (0.012 +/- 0.001 g), each, in twelve 21-l plastic tanks, fed for 45 days, then infected with Streptococcus iniae. The herbal supplements did not change the average weight gain, feed conversion rate, or specific growth rate. However, mortality from S. iniae in all herbal-treated groups was significantly lower than in the control. Thus, thyme, rosemary, or fenugreek can be used as immunostimulants to enhance immune response and disease resistance to S. iniae during first-feeding O. mossambicus fry.