Rainbow Runner

The Rainbow Runner (Elagatis bipinnulata) is a striking and swift pelagic fish belonging to the Carangidae family, commonly known as jacks. Also recognized by names such as rainbow yellowtail, Spanish jack, and Hawaiian salmon, this species is a familiar sight in tropical and subtropical waters worldwide.

These highly streamlined fish are primarily pelagic, inhabiting the upper water column, often near the surface, but can be found at depths ranging from 0–164 m. They thrive in warm waters, typically between 21–31.7°C, with a preferred range of 22.8–28.8°C. Rainbow Runners are frequently observed in schools, patrolling current-swept reef edges, deep clear lagoons, and offshore areas, often associating with floating structures or debris. As fast-swimming carnivores, their diet consists of small fish, cephalopods like squid, and various pelagic crustaceans such as shrimp and crabs. Divers at the Fish Bowl dive site commonly encounter this species. The Rainbow Runner is currently listed as "Least Concern" by the IUCN, indicating stable and widely distributed populations globally.

Identification

• Size: While the maximum recorded size is 1.2 m, individuals can occasionally reach up to 1.8 m (6 ft) in length, though divers more commonly encounter fish in the 60–90 cm (2–3 ft) range.
• Body Shape: The Rainbow Runner possesses a distinctive, elongated, and highly streamlined body, often described as torpedo-shaped or fusiform. It is notably more slender than many other members of the jack family, tapering gracefully towards both its pointed head and deeply forked tail.
• Coloration: The upper body is typically a dark olive-blue to blue-green, transitioning to white or silvery on the underside, sometimes with a subtle yellow or pink cast.
• Distinctive Stripes: The species is easily identified by its vibrant lateral stripes. Two narrow, light blue or bluish-white horizontal stripes run along each side of the body. Between these lies a prominent, broader olive to brilliant-yellow stripe that extends from the snout to the base of the tail.
• Fins:
  • The caudal fin is large, deeply forked, and typically yellow.
  • A key identification feature is the presence of two separate finlets located behind both the second dorsal fin and the anal fin.
  • The first dorsal fin has six spines, while the second has one spine followed by 25–30 soft rays.
  • The anal fin features a single detached spine, followed by 16–18 soft rays.
  • Other fins often display a greenish or olive-yellow tint.
• Other Features: It has a relatively small mouth that does not extend past the front margin of the eye, and small eyes. The lateral line has a slight anterior arch and lacks scutes.

The Rainbow Runner (*Elagatis bipinnulata*) is a highly migratory, pelagic species found throughout the world's tropical and warm temperate oceans. These fast-swimming fish are often encountered by divers in a variety of environments, from coastal areas to the open ocean. Here's a breakdown of their preferred habitats:

• General Environment: Rainbow Runners are primarily *pelagic*, meaning they inhabit the open water column. They are frequently observed near the surface, but their range extends deeper.
• Depth Range: While commonly found in the upper water column, Rainbow Runners can be encountered at depths from the surface down to approximately 164 m (538 ft). Some sources indicate a maximum depth of 150 m. Juveniles are often found in shallower waters, sometimes as shallow as 2–10 m.
• Ecosystem Associations:
  • *Reefs and Drop-offs:* They are frequently associated with current-swept reef edges, coral reefs, and rocky reef systems, particularly where there are drop-offs.
  • *Open Ocean:* Beyond coastal areas, Rainbow Runners are abundant in mid-ocean environments. They often congregate around floating objects or debris, such as logs, Sargassum mats, or artificial Fish Aggregating Devices (FADs).
  • *Coastal Waters:* While preferring offshore conditions, they can also be found in deep coastal waters and occasionally enter lagoons for short periods. Juveniles have even been reported in estuary systems.
• Temperature Preference: These fish thrive in warm, tropical, and subtropical waters, typically found in temperatures ranging from 21–31.7°C (70–89°F), with a preferred range of 22.8–28.8°C (73–84°F). Larvae and juveniles in the Indo-Pacific have been observed in surface waters between 26.5° and 29.9°C, with peak occurrences around 28.0°C.
• Social Behavior: Rainbow Runners often form small polarized groups or large schools, especially around reefs and floating structures, making them a common sight at many dive sites. Young fish may swim in relatively loose, small schools, while older fish can be more solitary.
• Geographic Distribution: This species boasts a circumtropical distribution, inhabiting tropical and subtropical waters worldwide.
  • *Western Atlantic:* From Massachusetts and Bermuda south to northeastern Brazil, including the Gulf of Mexico and the Caribbean Sea.
  • *Eastern Atlantic:* From the Azores and Canary Islands to Angola, with records in the Mediterranean Sea.
  • *Indo-Pacific:* Widespread throughout the Indo-Pacific, including East Africa, the Red Sea, India, Thailand, Indonesia, the Philippines, Japan, Australia, New Zealand, and the Hawaiian Islands, though rare or absent in the Persian Gulf.
  • *Eastern Pacific:* From the mouth of the Gulf of California, Mexico, south to Ecuador, including the Galapagos Islands.

The Rainbow Runner (Elagatis bipinnulata) is a striking and swift pelagic fish belonging to the Carangidae family, commonly encountered by divers in tropical and subtropical waters worldwide. Known for its torpedo-shaped body and brilliant coloration featuring olive-green to blue dorsally, a silvery-white belly, and two distinct narrow light blue or bluish-white horizontal stripes straddling a broad olive or yellowish stripe, it is a captivating sight underwater.

• Underwater Encounter Behavior: Rainbow Runners are fast-swimming and often observed in schools, ranging from small groups to large aggregations of hundreds of individuals. While primarily an open-water species, they frequently cruise near the surface over reefs, drop-offs, and seamounts, and can also be found in coastal waters close to reef systems. They are known to be curious fish and may approach and circle scuba divers for a few circuits before moving on, showcasing their powerful and rapid swimming capabilities. Juveniles have been reported near floating seaweed and debris, using them for shelter.
• Feeding Habits: As active carnivores, Rainbow Runners are opportunistic predators that utilize their speed to capture a wide range of prey. Their diet primarily consists of small fishes, cephalopods (such as squid), and various pelagic or planktonic crustaceans, including shrimp and crabs. They are known to be selective, often preferring prey smaller than themselves.
• Social Structure: Rainbow Runners typically form schools, which can vary in size. These schools are often observed associating with other open-water fishes like tunas and billfishes. They are also strongly attracted to floating structures, such as fish-aggregating devices (FADs), and natural drifting objects, where large concentrations can gather.
• Notable Seasonal Patterns: Spawning in Rainbow Runners can occur year-round in warmer waters, particularly those consistently above 27°C. However, even with year-round spawning, seasonal peaks are observed, for instance, in May and December–January in the Western Pacific Ocean. Reproduction involves pair courtship and the release of pelagic eggs and larvae into offshore waters. While specific migratory patterns for adults are not extensively documented for divers, juveniles are known to migrate from equatorial spawning grounds, sometimes drifting under Sargassum mats. Divers may encounter them consistently at dive sites like Fish Bowl due to their circumtropical distribution and preference for warm waters.