Southern Flounder
The Southern Flounder — called lenguado in Argentina — is a native flatfish found along the Buenos Aires coast and in estuaries like Bahía Blanca.
It draws a small but dedicated following of shore and boat anglers, and has become the target of a pioneering fly-fishing scene led by guides like Ceferino Traverso, who proved these fish can be taken on the fly in the shallow coastal flats.
Scientific Name: Paralichthys orbignyanus
Also known as Lenguado, Brazilian flounder, mud flounder
- Classic flatfish shape — both eyes on the left side of the body, lying flat on the bottom; brown to olive-grey on top with pale spots, white underneath.
- Females grow significantly larger than males; females can reach 87 cm and several kilograms, while males top out well short of that.
- The wide, asymmetrical mouth is set for ambushing prey from below; the lateral line curves sharply above the pectoral fin.
What to know
Habitat Distribution
- Native to the southwestern Atlantic coast of Argentina — found in coastal lagoons, estuaries, and shallow nearshore waters along the Buenos Aires province coastline.
- Closely associated with the Bahía Blanca estuary, where commercial and sport catches have been well documented; also present in the Río de la Plata biogeographic zone.
- Prefers shallow water over mud and soft-bottom substrates, often in areas of reduced salinity where estuaries mix with the sea.
- Adults move offshore or out of estuaries during the spawning period, then return to feed and recover in the shallower inshore areas through spring and summer.
Key Locations
- Bahía Blanca estuary (Buenos Aires province) — the most studied and documented location for this species in Argentina, with documented sport and commercial catches.
- Buenos Aires province coastline — shallow coastal flats and estuarine systems along this stretch are the core of the sport fly-fishing scene for flounder pioneered by local guides.
Specific Spots
- Shallow mud flats and soft-bottom shallows inside estuaries — flounder lie motionless and ambush prey from below, so flat, featureless-looking bottom is exactly where to look.
- Current edges and tidal channels where baitfish and crustaceans concentrate as water moves in and out of the estuary.
- Transition zones where fresh river water meets saltwater — lower salinity areas are a consistent holding zone for this species.
Southern Flounder FAQ
Answers from onWater's species guide.
What are the best lures and bait for Southern Flounder?
Soft-plastic shrimp and paddle-tail swimbaits on 1/4 to 1/2 oz jig heads, worked with a slow drag-and-pause retrieve along the bottom, are the most consistent producers.
What flies work for Southern Flounder?
Clouser Minnows (which imitate small baitfish) in white, chartreuse, or tan are the foundational flounder fly, the weighted eyes get the hook riding up and keep the fly near the bottom where flounder strike.
When is the best time to fish for Southern Flounder?
Spring (September–November), adults return to inshore estuarine shallows after the offshore spawning period; fish are hungry and accessible. Summer (December–February), peak feeding season in the shallows; the most consistent window for both conventional and fly anglers along the Buenos Aires coast.
How do you catch Southern Flounder?
Most anglers fish the shallow estuarine flats from shore or by wading, working lures or flies slowly along the bottom. The fly-fishing approach, developed by local guides on the Buenos Aires coast, involves sight-fishing or blind-casting across shallow mud flats with weighted streamers stripped slowly back toward the...
What do Southern Flounder eat?
Feeds primarily on small fish and crustaceans, shrimp, small baitfish, and invertebrates that live on or near the soft bottom. Streamer flies and soft-plastic lures that imitate small baitfish are the go-to imitations.
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