Flag-tailed Porthole Catfish

Dianema urostriata is an uncommon and highly desirable relative of the Porthole Catfish, native to the blackwater Rio Negro and Rio Branco systems of northern Brazil. The species shares the slender, active build of D. longibarbis but is immediately distinguished by its boldly striped black-and-white caudal fin, which fans out strikingly when the fish is swimming in open water. Like its relative, it tends to swim at mid-water level rather than rest on the bottom.

In the aquarium, Flag-tailed Porthole Catfish require somewhat more attention to water quality and chemistry than D. longibarbis, doing best in soft, slightly acidic water with good filtration and regular water changes. They are active during the day and appreciate the company of conspecifics or other peaceful schooling fish. A planted tank with open swimming areas suits them well.

This species is ideally suited to a blackwater Rio Negro biotope alongside small tetras, apistogrammas, and small pencilfish. Feed them a varied diet of small sinking pellets, frozen bloodworm, daphnia, and brine shrimp nauplii for best condition and breeding behaviour.

Water: 23–28°C, pH 5.5–7.0, soft water preferred (GH 1–8); sensitive to poor water quality. Tank: 100 L minimum; dark substrate; dense planting with open swimming lanes; driftwood and leaf litter. Feeding: Small sinking pellets, frozen bloodworm, daphnia, brine shrimp; varied diet essential. Breeding: Bubble nest builder; rarely bred in captivity; requires very soft acidic water and live food conditioning. Compatibility: Peaceful; best with small tetras, pencilfish, and apistogrammas in a blackwater biotope.