The zebrafish is a well-established model system used to study and understand various human biological processes. The present study used OCT to investigate growth of the adult zebrafish brain. Twenty zebrafish were studied, using their standard lengths as indicators of their age. Zebrafish brain aging was evaluated by analyzing signal attenuation rates and texture features in regions of interest (ROIs). Optical scattering originates from light interaction with biological structures. During development, the zebrafish brain gains cells. Signal attenuation rate, therefore, increases with increasing zebrafish brain age. This study's analyses of texture features could not identify aging in zebrafish brain. These results, therefore, indicated that the OCT signal attenuation rate can indicate zebrafish brain aging, and its analysis provides a more effective means of observing zebrafish brain aging than texture features analysis. Using OCT system could further increase the technique's potential for recognition and monitoring of zebrafish brain development.