Like all Trachinops species, T. caudimaculatus swims with an unusually exaggerated undulating pattern; the common name "hulafish" is a reference to this behavior's superficial resemblance to the hula dance.

[1] Color varies between individuals, though the dorsal half of the head and body is typically grey, the ventral side a cool-toned tan, and the paired fins transparent and colorless.

[7] They prefer to live in large, dense shoals consisting of hundreds or thousands of individuals, though groups as small as 20 have been recorded.

[2][9] Though they may disperse far from their hatch site as larvae, adult southern hulafish are extremely unlikely to ever leave their home reef after settling and have never been recorded traveling through more than 20 meters of open water.

[2] In the absence of adult conspecifics, T. caudimaculatus juveniles are more likely to settle in areas of dense macroalgae growth than on their more typical rocky reefs, a decision that ultimately leads to high mortality rates as such habitats provide effective camouflage for their predators.