Astronotus crassipinnis
The darker, less-celebrated cousin of the common oscar, Astronotus crassipinnis is a deep-bodied cichlid from the southern Amazon and upper Paraguay-Paraná river systems of South America.
Where the common oscar flashes bold orange and red, this species settles into a somber olive-to-black palette broken by irregular blotching — a fish built for floodplain life rather than the aquarium trade.
Adults shift toward a diet dominated by smaller fish and mollusks, making them a genuine target for anglers working tropical lowland waters.
Scientific Name: Astronotus crassipinnis
Also known as Fat Oscar, Oscar, Apaiari, Cará-açu
- Tall, deep body with a large head, prominent eye, and a wide protrusible mouth — the classic heavy-set cichlid profile shared with the common oscar.
- Dark olive to near-black ground color broken by irregular lighter blotching and marbling; noticeably less colorful than the common oscar (Astronotus ocellatus).
- Key ID mark: a single black, light-ringed eyespot sits on the upper caudal peduncle at the tail base — but unlike the common oscar, there are no bright ocelli along the dorsal fin base.
- Juveniles wear a striking yellow-and-black banded pattern before fading into the darker adult coloration; adults typically reach about 25 cm (roughly 10 inches) total length.
What to know
Habitat Distribution
- The southern Amazon basin — particularly the upper Madeira River — and the upper Paraguay-Paraná drainages are its native waters; it has since been introduced to the upper Paraná River floodplain beyond that native range.
- Warm, slow-moving floodplain rivers and backwaters are its core environment; spends time near the bottom but moves through the water column in search of prey.
- Strictly a tropical freshwater species — not found in temperate or cold-water systems.
Specific Spots
- Adults settle near the bottom in slower floodplain water where structural cover concentrates prey fish and mollusks — deeper channel edges and submerged woody debris are worth working.
- Juveniles school in shallower, vegetated margins, using group numbers and their bold banded coloration as cover before dispersing as solitary adults.
Astronotus crassipinnis FAQ
Answers from onWater's species guide.
What are the best lures and bait for Astronotus crassipinnis?
Baitfish imitations, spinners, small crankbaits, and soft-plastic swimbaits, suit the adult's fish-heavy diet; natural bait including small live or cut fish and mollusks also works well.
What do Astronotus crassipinnis eat?
Juveniles eat broadly, insects, small invertebrates, plant material, but adults narrow sharply to smaller fish and mollusks, so baitfish-style presentations are the most relevant approach when targeting grown fish.
Where do Astronotus crassipinnis live?
The southern Amazon basin, particularly the upper Madeira River, and the upper Paraguay-Paraná drainages are its native waters; it has since been introduced to the upper Paraná River floodplain beyond that native range.
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