<![CDATA[Structured business financial management is a crucial factor for the sustainability of fish farming groups, particularly for groups receiving government assistance that are required to submit periodic accountability reports. This study aims to describe and analyze fish farmers' understanding of financial management in tilapia aquaculture in Sumberdem Village, Malang Regency, as a basis for designing a simple bookkeeping format. This study employed a qualitative approach using Robert E. Stake's instrumental case study design and Max Weber's Social Action Theory. Data were collected through observation, in-depth interviews with board members and active members of Pokdakan Sumber Gelang, and documentation, then analyzed using the interactive model of Miles, Huberman, and Saldaña. The findings reveal that the fish farmers' understanding is oriented toward instrumentally rational action (zweckrational). This is demonstrated through cost-benefit calculations during the commodity transition from catfish to tilapia, efficiency considerations in selecting the treasurer, the use of market price information in seeking alternative buyers, and compliance with reporting evaluations to members and the Fisheries Office. However, technical capacity limitations result in field recording practices remaining informal and mixing income and expense transactions in a single logbook, while technical data for each pond remain undocumented. In conclusion, fish farmers possess a strong foundation of rational awareness but face constraints in technical execution, making their rationality bounded in practice. These findings emphasize the necessity of developing a simplified bookkeeping format that separates cash flows and includes pond monitoring sheets to bridge the gap between rational understanding and daily financial management practices.]]>
