Roa is one of our favourite genus of deepwater butterflyfish and although it contains at least four members, only Roa excelsa is frequently covered. All Roa species are patterned in the same template of brown and white vertical bands, and are deepwater fish capable of living in depths up to 400ft. Of which, R. modestus is the commonest and can be found in the South-China Seas and Japan. It is peculiar however that in Hong Kong, they can be found in waters as shallow as 5-10m during winter, while in other parts of their range they are found relatively deeper.
In the similar but more popular Hawaiian endemic R. excelsa, the brown takes on a more golden hue, and the best way to describe the colour would be that of slightly burnt caramel, at the intermediate phase where sugar is a golden brown just before it starts to burn. R. excelsa has the most tapering bands of all the Roa species, being acute at the top nearer to the dorsal fin. Its ocelli on the soft dorsal fin is also oblong, compared to Roa modestus which we are featuring today.
As mentioned above, R. modestus is the commonest and also the cheapest member of the genus. They are seasonally common in the aquarium trade, but only domestically where they are caught. In Hong Kong, Taiwan and Japan, R. modestus is an affordable and frequently encountered butterflyfish. Because they can be found in shallower levels during winter, they are more easily collected compared to R. excelsa. Their geographical range also allows for easy collection compared to deepwater Hawaii for R. excelsa. Roa jayakari and Roa australis are two other members who are almost never seen, and they are often trawled up as by catch from commercial fisheries. There may be at least one more undescribed species of Roa from the Philippines.
R. modestus as seen above is pleasantly coloured in light coffee brown and white. Unlike the other members of its genus, it has very even and non tapering bands that run vertically down the body. In properly collected individuals, they may do well in aquariums, but will usually need a couple of days or a week to settle down and start taking prepared foods. It is important to note that Roa modestus, like all other Roa species, benefit from slightly cooler temperatures. It is a pity this fish isn’t more common in the American and European market. It’s beauty and affordable price makes it a good substitute for the uber expensive Roa excelsa.