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Pseudorhombus jenynsii, commonly known as the Small-toothed Flounder, is a species of flatfish belonging to the family Paralichthyidae. It is characterized by its flattened, oval-shaped body and eyes located on the left side of its head. This species is a demersal fish, typically found on sandy or muddy substrates in coastal waters, where its cryptic coloration provides excellent camouflage. It is an active predator, ambushing small invertebrates and fish.
Physical Characteristics
- Body shape
- flat
- Coloration
- Dorsal surface is typically mottled brown, grey, or olive, often with irregular darker spots and blotches, providing excellent camouflage against sandy or muddy bottoms. The ventral (blind) side is white. Some individuals may exhibit ocelli (eye-like spots) on the eyed side.
- Scale type
- ctenoid
- Mouth position
- terminal
- Distinctive features
- Eyes on the left side of the head (sinistral), Small, pointed teeth in both jaws, Lateral line strongly arched above the pectoral fin, Presence of small, dark spots or rings on the eyed side
- Dorsal fin
- Originates anterior to the upper eye, with 70-80 soft rays. No spines.
- Tail fin
- Rounded to slightly truncate caudal fin.
- Pectoral fin
- Well-developed on both sides, but larger on the eyed side. 10-12 rays.
- Distinctive fins
- Pelvic fins are symmetrical and short, with 6 rays each. Anal fin has 55-65 soft rays.
Identification Tips
Eye Position
Always check that both eyes are on the left side of the head. This distinguishes it from dextral (right-eyed) flounders.
Teeth
Carefully examine the mouth for small, pointed teeth in both jaws, a key feature for the genus Pseudorhombus.
Lateral Line
Note the distinct arch in the lateral line above the pectoral fin on the eyed side.
Coloration and Markings
Observe the mottled brown/grey coloration and any irregular dark spots or rings on the eyed side, which aid in camouflage.
Fin Ray Counts
For definitive identification, especially from similar species, accurate counts of dorsal (70-80) and anal (55-65) fin rays can be crucial.
Habitat
- Water type
- saltwater
- Depth
- Typically found in depths ranging from 10 to 100 meters, occasionally shallower or deeper.
- Environment
- Demersal, inhabiting sandy or muddy bottoms of continental shelves and coastal waters, including estuaries and bays. Prefers soft substrates for burrowing and camouflage.
- Geographic range
- Indo-West Pacific, including waters off Australia (primarily southern and eastern coasts), New Zealand, and potentially parts of Southeast Asia.
Aquarium Information
- Care level: expert
- Temperament: semi-aggressive
- Diet: carnivore
- Minimum tank size: 200 gallons
- Temperature: 20-26°C (68-79°F)
- pH level: 8.1-8.4
- Hardness: 8-12 dKH
- Compatibility: Not suitable for typical home aquaria due to size and specialized needs. If kept, only with other large, robust, non-aggressive fish that won't be preyed upon.
- Special requirements: Requires a large tank with a deep sand bed for burrowing, excellent filtration, and stable water parameters. Live food or high-quality frozen meaty foods are essential. Not commonly available in the aquarium trade.
Wild Information
- Conservation status: least concern
- Seasonality: Can be caught year-round, but local regulations and seasonal abundance may vary.
- Market price: Varies by region and catch; generally moderate.
- Commercial importance: medium
- Taste: Mild, delicate
- Texture: Flaky, white flesh
- Cooking methods: Pan-fried, Baked, Steamed, Grilled
- Nutritional value: Good source of lean protein and omega-3 fatty acids.
Key Facts
Master of Camouflagebehavior
The Small-toothed Flounder can rapidly change its skin coloration and pattern to perfectly match its sandy or muddy surroundings, making it incredibly difficult for predators and prey to detect.
Left-Eyed Flatfishinteresting
Like all members of the family Paralichthyidae, Pseudorhombus jenynsii is a 'left-eyed' flounder, meaning both eyes migrate to the left side of its head during larval development.
Ambush Predatorbehavior
This flounder is an ambush predator, burying itself partially in the substrate and waiting for unsuspecting small fish, crustaceans, and other benthic invertebrates to pass by before striking rapidly.
Taxonomic Stabilityevolution
The species Pseudorhombus jenynsii has maintained relatively stable taxonomy since its description, with few major synonymies or reclassifications, indicating a well-defined species.
Safety Information
Safe- Safety level: safe
- Venomous: No
- Edibility: edible
- Handling notes: No specific handling precautions are required beyond standard fish handling practices to avoid fin pricks. The fish is not venomous or dangerous. Handle carefully to avoid damaging its delicate skin and fins.
Similar Species
Largescale Flounder
Pseudorhombus arsius
P. arsius generally has larger scales, a more pronounced dark spot on the lateral line, and typically fewer dorsal and anal fin rays (D: 69-76, A: 53-59). Its teeth are also small, but P. jenynsii often has a more slender body shape.
Four-eyed Flounder
Pseudorhombus diplospilus
P. diplospilus is distinguished by having two prominent, dark, ocellated spots on the lateral line, one above and one below, which are typically absent or less distinct in P. jenynsii. Fin ray counts also differ (D: 70-77, A: 55-60).
Spotted Flounder
Pseudorhombus oculocirris
P. oculocirris has distinct ocellated spots on the body and often small cirri (fleshy filaments) on the eyes, which are absent in P. jenynsii. Fin ray counts are also slightly different (D: 68-75, A: 52-58).
Scientific Classification
- Kingdom
- Animalia
- Phylum
- Chordata
- Class
- Actinopterygii
- Order
- Pleuronectiformes
- Family
- Paralichthyidae
- Genus
- Pseudorhombus
- Species
- jenynsii
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