Bluefin Trevally Omilu Fish

Bluefin Trevally (Omilu): Fun Facts, Traits, Habitat, Diet

Welcome to the captivating world of the Bluefin Trevally, also known as Omilu. This fascinating fish is a member of the jack family, Carangidae, and is known for its striking electric blue fins and spots. In this article, we’ll dive into the physical characteristics, distribution, and habitat of this stunning marine predator. So, put on your virtual snorkeling gear, and let’s explore the life of the Bluefin Trevally.

10 Amazin Blue Trevally Fun Facts

Here are some interesting fun facts you may not have known about the Omilu fish species:

  1. Color-changing camouflage: The Bluefin Trevally can change its coloration to blend in with its surroundings, making it nearly invisible to both prey and predators.
  2. High-speed hunters: Bluefin Trevallies are known to reach speeds of up to 40 km/h (25 mph) when chasing prey, making them one of the fastest fish in the ocean.
  3. Living under the radar: Despite being an important game fish, the Bluefin Trevally is often mistaken for other fish species due to its similar appearance, making it an underappreciated and lesser-known fish.
  4. Clever cooperation: Bluefin Trevallies have been observed hunting alongside dolphins, taking advantage of the confusion created by the dolphins’ feeding frenzy to catch their own prey.
  5. Shark whisperer: The Bluefin Trevally is known to follow sharks around, picking off any leftover scraps from the shark’s meal and even eating parasites from the shark’s body.
  6. A taste for flying fish: Bluefin Trevallies have been known to leap out of the water to catch flying fish mid-flight, showcasing their incredible agility and hunting skills.
  7. Nocturnal gatherings: Although Bluefin Trevallies are mostly solitary during the day, they tend to gather in large groups at night. The exact reason for this behavior is still a mystery to scientists.
  8. A long lifespan: Bluefin Trevallies have been known to live up to 20 years in the wild, making them one of the longer-lived members of the jack family.
  9. Natural-born leaders: Juvenile Bluefin Trevallies are often found leading schools of other fish species, guiding them through the ocean and potentially increasing their own chances of finding food.
  10. A unique nickname: In the Seychelles, the Bluefin Trevally is known as “Mademoiselle Bleu,” which translates to “Miss Blue,” highlighting the fish’s striking appearance and capturing the admiration of locals.
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A Quick Look at the Bluefin Trevally

Scientific NameCaranx melampygus
SpeciesC. melampygus
Common namesBluefin trevally, Omilu, Bluefin jack, Bluefin kingfish
Description and AppearanceThe bluefin trevally has a streamlined, elongated body with a dark blue upper body, silvery sides, and bright blue fins. They have 30-35 dorsal fin rays, 8-9 anal fin rays, and a forked caudal fin for fast swimming.
SizeUp to 117 cm in length and 43.5 kg in weight
HabitatCoral reefs, lagoons, and open water near the coast; adults prefer deeper settings, while juveniles and subadults prefer protected environments
DistributionTropical and subtropical regions of the Indo-Pacific, from the Red Sea to Hawaii and the southern coast of Japan to Australia
DietPrimarily fish, cephalopods, and crustaceans; juveniles consume more crustaceans than adults
Hunting TechniquesDiverse, including midwater attacks, reef ambushes, and foraging interactions
ReproductionSexual maturity is reached at 30-40 cm in length. Spawning occurs throughout the year, with peak spawning during summer months. Eggs and larvae are pelagic. Multiple spawner, up to 8 times per year, with up to 6 million eggs per year in captivity
Growth194 mm in the first year, 340 mm in the second year, and 456 mm in the third year
LifespanUp to 20 years
Ecological rolePredatory fish, important for controlling prey populations within their ecosystem
PredatorsLarger fish, sharks, and humans
Conservation statusLeast Concern (IUCN Red List)
Economic importancePopular game fish and targeted for commercial fisheries, important for local economies and food security
Human interactionOccasionally caught by recreational anglers, but generally not harmful to humans; ciguatera poisoning reported in some cases
EvolutionBluefin trevally evolved within the Caranx genus, which includes other large predatory fish such as jacks and kingfish
AdaptationsStreamlined body and forked tail for speed and agility, keen vision for locating prey, strong jaws for crushing prey
Research and discoveriesStudies on feeding behavior, reproduction, and growth patterns have helped inform fisheries management and conservation strategies; overfishing in Hawaii led to increased research in aquaculture
Captivity and aquarium tradeNot commonly kept in aquariums due to size and predatory nature, but displayed in public aquariums for educational purposes

The Beauty of the Bluefin Trevally: Features and Characteristics

The Bluefin Trevally is an eye-catching fish with a large, oblong, and compressed body. The most distinctive feature of this species is its electric blue dorsal, anal, and caudal fins, which contrast beautifully with its silver-brassy upper body. The fish is also adorned with blue hues and black spots, adding to its vibrant appearance.

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Measuring up to a maximum length of 1.2 meters (3.8 feet) and weighing up to 43.5 kilograms (96 pounds), the Bluefin Trevally is a formidable predator in the ocean. Its pointed snout gives it an aerodynamic advantage when swimming and hunting, making it a swift and efficient hunter.

Exploring the Bluefin Trevally’s World: Distribution and Habitat

The Bluefin Trevally is a well-traveled fish, with its range stretching from Eastern Africa to Central America, and from Japan to Australia. It thrives in the tropical and subtropical waters of the Indian and Pacific Oceans, making it a common sight for divers and snorkelers in these regions.

In terms of habitat, the Bluefin Trevally can be found in both inshore and offshore environments. Younger fish, known as juveniles, prefer shallow, protected waters such as bays, lagoons, and shallow reefs. As they grow, they venture into deeper waters, inhabiting offshore environments like deeper reefs, atolls, and bomboras. This adaptability allows the Bluefin Trevally to thrive in various marine settings and avoid overpopulation in any specific area.

A Bluefin Trevally’s Diet and Feeding Habits

As a predatory fish, the Bluefin Trevally’s diet consists primarily of other fish, cephalopods (like squid), and crustaceans (like crabs and shrimp). Interestingly, the diet of juvenile Bluefin Trevallies tends to be more focused on small crustaceans, while adult fish diversify their menu to include a wider range of prey.

The Bluefin Trevally employs a variety of hunting techniques, from aggressive midwater attacks to stealthy reef ambushes and foraging interactions with other marine life. On average, a Bluefin Trevally consumes around 45 kilograms of fish per year, making it an essential part of the ocean’s food chain. They are known to hunt both solitary and in groups, showcasing their adaptability and intelligence as predators.

Reproduction and Growth

The Bluefin Trevally reaches sexual maturity at a length of 30-40 centimeters (11.8-15.7 inches) and at around 2 years of age. This species is a multiple spawner, meaning it can spawn up to 8 times per year, ensuring a constant supply of new Bluefin Trevallies in the ocean.

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In captivity, a Bluefin Trevally has been known to release up to 6 million eggs per year, but the numbers in the wild may vary. Growth rates for this species show that they can reach 194 millimeters (7.6 inches) in their first year, 340 millimeters (13.4 inches) in their second year, and 456 millimeters (18 inches) in their third year.

Bluefin Trevally in Commercial and Recreational Fishing

The Bluefin Trevally’s beauty and strength make it a popular target for both commercial and recreational fishing. In the west Indian Ocean alone, up to 50 tonnes of Bluefin Trevally are taken each year. In Hawaii, around 700 pounds are caught annually by anglers.

However, overfishing in Hawaii has led to increased research in aquaculture to maintain a sustainable population. Additionally, some cases of ciguatera poisoning have been reported from consuming Bluefin Trevally, so it’s essential to be cautious when cooking and eating this fish.

Bluefin Trevally Taxonomy and Phylogeny

The Bluefin Trevally belongs to the genus Caranx within the family Carangidae. This family, also known as the jack family, comprises many well-known and powerful predatory fish species. The Bluefin Trevally was first described by Georges Cuvier in 1833 as Caranx melampygus, and its taxonomy was later revised by Frederick Berry in 1965.

Biology and Ecology

As a juvenile, the Bluefin Trevally is a schooling species, often found swimming and hunting with other young fish. However, as it matures into an adult, it becomes more solitary and establishes a well-defined home range. Adult Bluefin Trevallies are known to form spawning aggregations while hunting, working together to maximize their chances of a successful catch.

Interestingly, the nighttime movements of the Bluefin Trevally are less extensive than their daytime movements, possibly due to reduced visibility and a different set of prey available at night. Over several months, this species may range up to 10.2 kilometers (6.3 miles) in search of food and suitable habitats. One fascinating behavior observed in the Bluefin Trevally is its interaction with the Galapagos shark; the fish has been known to rub itself against the shark’s skin to rid itself of parasites.

Conservation Status and Relationship to Humans

The Bluefin Trevally is currently listed as a species of Least Concern in terms of conservation status. This is due to its wide distribution and ability to adapt to various marine environments. However, it’s essential to keep an eye on fishing practices, as overfishing could lead to population decline in certain areas.

This species is highly valued by both commercial fisheries and recreational anglers, making it an essential part of the fishing industry. Unfortunately, catch statistics for the Bluefin Trevally are often poorly reported, making it difficult to gain an accurate understanding of the species’ population status.

While the Bluefin Trevally is considered a good to excellent food fish, it’s crucial to be cautious when consuming it. Some cases of ciguatera poisoning have been reported, a type of food poisoning caused by eating contaminated reef fish.

Other Fun Facts about the Bluefin Trevally

The Bluefin Trevally is a beautifully colored fish that captures the attention of divers, snorkelers, and anglers alike. Its fast and aggressive feeding habits make it an exciting species to observe and catch. Although it’s a smaller relative of the giant trevally, it still packs a punch in terms of strength and speed.

In Hawaii, the Bluefin Trevally is known as omilu, and it plays an essential role in Hawaiian fishing culture. One of the fascinating behaviors exhibited by this species is its ability to assume dark pigmentation to hide from potential threats or blend in with its surroundings. Lastly, the Bluefin Trevally can be sold fresh, salted, or frozen, and its firm, oily meat is considered a delicious treat by many seafood enthusiasts.

The Bluefin Trevally is a remarkable and captivating marine species that deserves admiration and respect. Its vibrant colors, swift hunting skills, and adaptability to various environments make it a fascinating subject for both marine biologists and fishing enthusiasts. So, whether you’re diving in the deep blue sea or casting a line from the shore, keep an eye out for the dazzling electric blue fins of the Bluefin Trevally.