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Lethrinus erythracanthus, commonly known as the Redfin Emperor, is a medium to large-sized marine fish belonging to the family Lethrinidae. It is characterized by its robust body, distinctive coloration, and prominent red or orange fins, particularly the pectoral and pelvic fins. This species is a significant component of reef ecosystems across its Indo-Pacific range, playing a role as a benthic predator. It is also a commercially important food fish in many regions.
Physical Characteristics
- Body shape
- compressed
- Coloration
- Body color is typically greyish-brown to olive-green dorsally, fading to lighter shades ventrally. Distinctive features include scattered orange or yellow spots on the head and body, particularly prominent on the operculum and cheeks. The most striking feature is the bright red or orange coloration of the pectoral, pelvic, and anal fins, and often the caudal fin margins. The dorsal fin may also have reddish hues. Some individuals may display irregular dark blotches or bars, especially when stressed or at night.
- Scale type
- ctenoid
- Mouth position
- terminal
- Distinctive features
- Bright red or orange pectoral, pelvic, and anal fins., Scattered orange or yellow spots on head and body., Relatively deep body with a steep dorsal profile., Large, prominent eyes., Terminal mouth with strong canine-like teeth at the front and molariform teeth on the sides.
- Dorsal fin
- Single dorsal fin with 10 spines and 9-10 soft rays. The spinous portion is relatively low, and the soft-rayed portion is slightly higher.
- Tail fin
- Moderately forked caudal fin, often with reddish margins.
- Pectoral fin
- Long and pointed pectoral fins, typically bright red or orange.
- Distinctive fins
- Pelvic fins are also bright red or orange, located thoracically. Anal fin has 3 spines and 8 soft rays, also often reddish.
Identification Tips
Fin Coloration
The most reliable identifier is the vivid red or orange color of the pectoral, pelvic, and anal fins. This is a consistent feature across its range.
Body Spots
Look for scattered orange or yellow spots on the head and body, particularly on the operculum and cheeks. These spots can vary in intensity but are usually present.
Body Shape
Note the relatively deep body and steep dorsal profile, characteristic of many Lethrinus species, but combined with the fin coloration, it aids identification.
Mouth and Teeth
Observe the terminal mouth with strong canine-like teeth at the front and molariform teeth on the sides, adapted for crushing shells of prey.
Habitat
- Water type
- saltwater
- Depth
- Typically found in depths ranging from 5 to 75 meters, occasionally deeper.
- Environment
- Inhabits coral reefs, rocky reefs, sandy bottoms, and seagrass beds, often in areas adjacent to reefs. Juveniles may be found in shallower, more protected areas. Adults are often solitary or found in small groups.
- Geographic range
- Widespread in the Indo-Pacific region, from the Red Sea and East Africa eastward to the Line Islands, north to southern Japan, and south to Australia (including the Great Barrier Reef) and New Caledonia.
Aquarium Information
- Care level: expert
- Temperament: semi-aggressive
- Diet: carnivore
- Minimum tank size: 500 gallons
- Temperature: 24-28°C (75-82°F)
- pH level: 8.1-8.4
- Hardness: 8-12 dKH
- Compatibility: Best kept in very large, species-specific tanks or with other large, robust, semi-aggressive fish. Not suitable for typical reef aquariums due to predatory nature.
- Special requirements: Requires a very large tank with ample swimming space and strong filtration. Live rock and sand substrate are beneficial. Will consume smaller fish and invertebrates. Requires a varied diet of meaty foods.
Wild Information
- Conservation status: least concern
- Seasonality: Available year-round in most parts of its range, though local fishing regulations and seasonal aggregations may influence availability.
- Market price: Varies by region and size, generally moderate to high.
- Commercial importance: high
- Taste: Mild, sweet, and delicate flavor.
- Texture: Firm, white, flaky flesh.
- Cooking methods: Grilling, Baking, Steaming, Frying, Sashimi
- Nutritional value: Good source of lean protein, omega-3 fatty acids, and essential vitamins and minerals.
Key Facts
Nocturnal Foragerbehavior
Redfin Emperors are primarily nocturnal feeders, using their keen sense of smell and touch to locate prey on the seabed during the night.
Dietary Specialistbehavior
Their diet consists mainly of benthic invertebrates such as crabs, mollusks (gastropods and bivalves), echinoderms (sea urchins, brittle stars), and occasionally small fish. Their strong molariform teeth are perfectly adapted for crushing hard-shelled prey.
Protogynous Hermaphroditeevolution
Like many other Lethrinids, Redfin Emperors are believed to be protogynous hermaphrodites, meaning they start their lives as females and can later change sex to become males.
Important Fishery Speciesinteresting
Due to their size, good flesh quality, and widespread distribution, Redfin Emperors are an important target species for both commercial and artisanal fisheries throughout their range.
Color Variationinteresting
While the red fins are a constant, the intensity and pattern of the orange/yellow spots on the body can vary significantly between individuals and even change based on mood or habitat.
Safety Information
Handle with care- Safety level: caution
- Venomous: No
- Edibility: edible
- Handling notes: While not venomous, Redfin Emperors possess sharp dorsal and anal fin spines, as well as a strong bite. Care should be taken when handling to avoid punctures or bites. Use gloves and appropriate tools if handling live specimens. For consumption, ensure proper cleaning and cooking.
Similar Species
Spangled Emperor
Lethrinus nebulosus
Lethrinus nebulosus typically has blue spots and lines on the head and body, and its fins are generally not as intensely red or orange as L. erythracanthus. The body shape can also be slightly more elongated.
Yellowlip Emperor
Lethrinus xanthochilus
Lethrinus xanthochilus is characterized by prominent yellow lips and often a more yellowish overall body coloration. Its fins are not typically bright red or orange like L. erythracanthus.
Thumbprint Emperor
Lethrinus harak
Lethrinus harak has a distinctive dark, oval blotch (resembling a thumbprint) on its flank, which is absent in L. erythracanthus. Its fins are also not typically red.
Scientific Classification
- Kingdom
- Animalia
- Phylum
- Chordata
- Class
- Actinopterygii
- Order
- Spariformes
- Family
- Lethrinidae
- Genus
- Lethrinus
- Species
- Lethrinus erythracanthus
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