Anatomical study and distribution of taste buds in the palatal organs of various types of local koi fish (Cyprinus rubrofuscus) in Indonesia

Background: Koi fish (Cyprinus rubrofuscus), which are celebrated for their vibrant colors and cultural significance, are also valued in the ornamental fish industry. Despite extensive research on fish sensory biology, specific studies on taste buds in koi, especially among different ornamental varieties, are limited.
Aim: This study aimed to analyze the anatomical structure and distribution of taste buds in the palatal organs of six
popular koi varieties in Indonesia: Kohaku, Shiro, Showa, Sanke, Platinum, and Ogon.
Method: Eighteen koi fish, three of each variety and aged 4–6 months, were examined using histological techniques
and scanning electron microscopy.
Results: Although no macroscopic or histological differences were observed in the palatal organs across varieties,
significant variation in taste bud density was noted. The Ogon variety exhibited the highest average taste bud density
(23.95 ± 7.03), whereas the Shiro variety had the lowest (17.03 ± 5.26).
Conclusion: Statistical analysis revealed that taste bud density significantly differed among varieties, with the Ogon variety having a notably higher density than the Shiro and Sanke. These findings suggest that selective breeding of
ornamental traits may affect sensory function.