Filament Cory

Corydoras filamentosus is one of the most distinctive cories in the genus. Adult males develop striking filamentous extensions to the dorsal fin rays — elongated, thread-like projections that add a dramatic flair to an otherwise modestly patterned fish. The body is tan with small scattered spots and a faint lateral stripe, and both sexes display a dark humeral blotch.

Native to Suriname, this species inhabits coastal lowland streams with soft, slightly acidic water and fine sandy substrates. It is a rarely exported species that requires slightly more care than beginner cories due to its preference for clean, soft water and its sensitivity to sudden parameter changes.

In a well-maintained aquarium with stable water quality, C. filamentosus is a rewarding and long-lived fish. Keep in groups of six or more; the display of fin filaments among competing males is particularly impressive. Feed high-quality sinking foods and supplement with frozen or live invertebrates to bring out the best colouration and finnage.

Water: Soft and slightly acidic, pH 5.8–7.2, temperature 22–26°C; clean, well-filtered water essential. Tank: 80 L with fine sand, scattered driftwood and leaf litter; gentle to moderate flow. Feeding: Sinking pellets, frozen bloodworm, Daphnia, and Mysis shrimp; high-protein diet enhances fin development. Breeding: Rarely bred in captivity; soft water and live food conditioning suggested; males display filaments during courtship. Compatibility: Peaceful; best with other soft-water species from South America.