Tilapia lake virus (TiLV) is a novel orthomyxo-like virus, and has genomic RNA material that is easily degradable. Hence, proper sample storage and preservation should be applied for accurate diagnostic results. In this study, we investigated various conditions for preserving tilapia tissues for the detection of TiLV. Our results revealed that RNAlater® and deep-freezing at −20 °C are the best practices to maintain TiLV genomic RNA for subsequent diagnosis. Samples stored in these conditions could maintain TiLV genomic RNA for 365 days with minimal reduction. In contrast, TiLV genomic RNA is substantially degraded in ethanol and on Whatman® FTA® classic cards with a reduction of TiLV genomic material of 2 logs and up to 3 logs within 30 days of storage, respectively. Besides, all preservation methods showed a difference in the amount of TiLV genomic RNA between the initial day, during, and after 30 days of storage. The benefits of this study can be applied to preserve samples efficiently and to transport samples properly from remote areas to a laboratory that is suitably-equipped for disease examination.