The yellow highfin spinytail, also known as the yellow triangle, triangle inverted dangle, golden dangle, and yellow triangle dangle, is a colorful fish native to the Pacific Ocean frontier of Japan and Hawaii.
Divers frequently encounter these vibrant fish around reefs at depths ranging from 2 to 46 meters.
Characterized by its bright yellow body color and a distinct white spine on its tail, the yellow highfin spinytail stands tall with large dorsal and anal fins. It possesses a slightly protruding mouth with a small opening at the tip. Algae, particularly seaweed, forms the primary diet of these fish.
Ovoid and laterally flattened, the yellow highfin spinytail boasts a prominent muzzle. Its mouth, though small, is terminal, housing large maxillary and mandibular teeth that are fixed and immovable.
These teeth are flattened and notched along the edges. In terms of coloration, adult fish exhibit a uniform bright yellow and brown hue after death. They bear numerous pale longitudinal lines along the center of their bodies, sharp dorsal and anal fins, and a long spine on each side of the caudal peduncle, accompanied by hair-like protrusions.
Their caudal fins are truncate. Juveniles, on the other hand, feature white bodies adorned with several light brown horizontal lines. Notably, their dorsal and anal fins are longer than those of adults.
In their natural habitat, adult yellow highfin spinytail fish can grow up to 20 cm long. However, when kept in a fish tank, their average size reaches around 12 cm. According to studies, yellow highfin spinytails living in their natural habitat can live for up to 30 years, while those in tanks typically have a lifespan of around 5 years.
In the perilous underwater world, the yellow highfin spinytail fish employs several strategies for self-defense. For instance, they darken their color at night to avoid detection by predators and revert to their original color at sunrise. Additionally, their two tail fin spines serve both as defensive mechanisms and weapons against predators.
The yellow highfin spinytail also contributes to reef cleaning as it primarily feeds on seaweed found on reefs. Interestingly, they have developed a symbiotic relationship with sea turtles, often seen trailing them to graze on the seaweed growing on their backs.
Fish enthusiasts often house yellow highfin spinytails with clownfish in the same tank as they tend to coexist harmoniously. Moreover, they can be kept with other compatible fish species such as longfin rosefish, lionfish, and eels. As the yellow highfin spinytail enjoys solitary movement, it is advisable to keep two or three of them together in a tank to prevent them from feeling lonely.
The distribution of yellow highfin spinytails encompasses various regions in the Pacific Ocean, including the Ryukyu Islands, Taiwan, the Marianas Islands, the Marshall Islands, Palau, Micronesia, and Hawaii.
Typically found in coral-rich lagoons and along seaward reef slopes, the yellow highfin spinytail fish dwells beneath the surf zone. They are usually observed alone or in small, loosely grouped populations amidst algal blooms attached to rocks. While their preference lies in feeding on algae, they also consume benthic organisms.
