This study was carried out to provide empirical information on the economic viability of fish farming in Kaduna State across various scales of production. The specific objectives of the study were to describe the socio-economic characteristic of fish farmers in the study area; determine costs and returns of fish farming at various scales; determine the technical relationship between production inputs and output in fish farming; quantify the level of technical efficiency of fish farmers operating at various scales of operation; determine the factors influencing technical efficiency of fish farming and describe the constraints limiting efficiency of fish farming in the study area. Primary data were collected with the aid of structured questionnaire administered to 115 fish farmers in 18 out of the 23 Local Government Areas of the State. The 115 fish farmers were identified through a pilot study of existing farms in the state. Descriptive statistics, farm budgeting technique and stochastic frontier production function were used to analyze the data while ANOVA was used to test hypothesis. The results showed that 42.6% of the fish farmers were within the productive age bracket of 40-49 years and the enterprise was male dominated (with 70.4%), while 57.4 of the farmers had only vocational education. The farming experience of 74.8% of the farmers was between 1 and 5 years indicating that majority of farmers are new in the enterprise. The study found out that fish farming was profitable at various scales of production with returns to investments of 1.97 and, given the current level of technology at the disposal of the fish farmers, they have a scope of improving on their current level of technical efficiency by 37%. The study also found that there was existence of economy of scale in fish farming in the study area as the average cost per stock was N86.35, N127.66 and N154.74 for the large, medium and small scale fish farmers, respectively, and the difference was statistically significant at 1% probability level. The study found that the return to scale in fish farming was less than unity (0.6971) indicating a positive decreasing return to scale. However it was observed that labor is over utilized. The ANOVA results show a significant difference in the profitability and efficiency of the fish farmers with F values of 8.24 and 21.11 respectively, both at 1% probability level. The major inefficiency factors were age and education which were statistically significant at 10% and 5%, respectively. The major constraints were pilferage, flooding and stunted growth. Part of the recommendation of the study is that fish farmers should be encouraged to join fish farmers' association so as to have access to fisheries inputs and knowledge on improved farming practices. It is also recommended that there is need to improve the technical knowhow of the fish farmers through workshops as they are yet to attain frontier level.