The study was conducted among randomly selected 180 respondents from 12 villages in 4 blocks of Katihar district in Bihar to identify the factors associated with the knowledge level of farmers for sustainable practices of makhana-cum-fish farming. An ex-post facto research design was employed for conducting the research systematically. The collected data were analysed using relevant statistical tools, and inferences were drawn. It was found that the majority of respondents (61.66%) had a medium level of knowledge about sustainable makhana-cum-fish culture practices. Spearman correlation analysis revealed that out of 23 independent variables, twelve variables were found positively and significantly correlated with the knowledge level of the respondents about sustainable makhana-cum-fish culture practices at the 1 percent level of probability: economic motivation (ρ =.672), mass media exposure (ρ =.671), innovativeness (ρ =.668), extension agency contact (ρ =.664), occupation (ρ =.620), risk orientation (ρ =.655), source of information (ρ =.654), farming experience (ρ =.573), education (ρ =.560), annual income (ρ =.522), family size (ρ =.439), and social participation (ρ =.337). The success of makhana-cum-fish farming depends on the farmers' knowledge level, and they can optimize their practices and techniques to produce high-quality yields by having more knowledge.