This species occurs in coral and rocky areas from 3-10 m (R. Myers pers. comm. 2008). It has been observed in coral atolls (Nanami and Nishihira 2004). Juveniles feed on small crustaceans including copepods, isopods, tanaids and cumaceans from algal mats, while adults consume polychaetes, sipunculids, gastropods, chitons and crustaceans including crabs, shrimps and hermit crabs (Shibuno et al. 1993).

It was reported to spawn during mid-morning, before 10:00 am (Moyer 1974, Meyer 1977), group or aggregate spawning (Meyer 1977) by the terminal phase was observed in the Japanese waters. There was no evidence of spawning during late morning and afternoon, and the observations of spawning were four days prior to the new moon (Moyer 1974). Breeding ground of this species is approximately 200 m², varying from nine to 11 m in depth. Water temperature was 27 °C (Moyer 1974).

Spawning begins with the arrival of large numbers of initial-phase fish at the coral or rocky areas, where they begin to mill about in increasingly tighter aggregations (Thresher 1984). The size of aggregations varies from a dozen to as many as several hundred individuals with different-sized aggregates. In addition, it has been reported to perform a “bobbing” motion while swimming with the entire body arcing up and down (Moyer 1974, Meyer 1977).

Moyer (1974) described the spawning behaviour of T. cupido in detail. During the first day of spawning, this species aggregates close to the rocks, and split periodically into three or four groups of close to 100 individuals each. Larger fish appeared to be about 10-13 cm in length and were obviously the aggressors. Only one or rarely two or three fish in each group dash up to discharge their reproductive clouds. Second day, the number of fish participating had decreased remarkably compared to the first day. On the fifth day, reproductive activity has almost ceased, but small individuals of about fifteen fish were sighted. Little herding and no clouds of reproductive materials were observed.

Hatched in a captivity laboratory environment, eggs of this species were found to be buoyant and spherical with a single spherical oil globule. Diameters ranged from 0.54 mm to 0.65 mm and spawning was observed from June to August in the morning between 0800 to 1200 (Kimura et al. 1998).

It exhibits similar colour patterns with T. purpureum, T. trilobatum, T. quinquevittatum and T. heiseri (Bernardi et al. 2004). It has been reported to be a protogynous hermaphrodite (Devlin and Nagahama 2002), however, gonadal histology has not been studied in any detail (Sadovy de Mitcheson and Liu 2008). It has been noted as one of the cleaner fishes in Japan (Kuwamura 1976).