Ehrhardt's Corydoras

Geographic Origin and Biotope: South America: coastal basins of southern Brazil (Tubarão, Itapocu, Iguaçu rivers). Being a southern species, it inhabits small subtropical streams subject to seasonal temperature fluctuations, with cool waters, muddy or sandy substrates, and dense riparian vegetation.

Taxonomy and Morphology: Well-defined species (Steindachner, 1910). Robust size up to 5.5 cm (2.2 inches). Round snout and moderately convex dorsal profile. Shares phenotypic similarities with Corydoras paleatus (Peppered Corydoras), with which it also partially shares the geographic range of thermal tolerance.

Social Behavior: Imperative gregarious behavior. Do not isolate the subjects: they need schools of at least 6-8 individuals to overcome instinctive shyness. They swim compactly sifting the base of plants, and show no interspecific or intraspecific aggressiveness.

Coloration and Sexual Dimorphism: Silvery-grayish base. Has three obvious and large dark or blackish spots (blotches) arranged along the midline of the body, plus a diffuse marbling on the back. Females noticeably more massive, round, and often slightly larger than males.

Aquarium Setup: Essential substrate of very fine edgeless sand. Widely planted tank rich in woody refuges to simulate forest banks. Provide a good current and large areas of surface shade via floating plants (Salvinia).

Diet and Feeding: Omnivorous detritivore. In the aquarium, it eagerly accepts specific dry food for scavengers (sinking tabs for carnivores). Mandatory thrice-weekly administration of live/frozen prey: bloodworms, tubifex, and brine shrimp, otherwise growth will stunt and wasting diseases will occur.

Water Quality: Subtropical species! Cooler optimal temperature compared to Amazonian corydoras: 20-25°C (68-77°F) (tolerates 18°C/64°F in winter). Not recommended for Discus tanks. Ideal pH 6.0-7.2. Indispensable to keep nitrates very low via strong filtration and siphoning.

Compatibility and Tankmates: Ideal for "unheated" tanks (in moderately heated apartments) or cool peaceful communities. Excellent with Gymnocorymbus ternetzi (Black Skirt Tetra), Tanichthys albonubes (White Cloud Mountain Minnow), and Danio rerio. Absolutely to be excluded pairing with turbulent or predatory cichlids.

Aquarium Reproduction: Reproduces with monsoon stimulations: heavy cold water changes lowering the temperature by 3-4°C (5-7°F). During "T-position" mating, adhesive eggs are distributed on glass, moss, or filters. Raising fry is undermined by the parents' appetite.

Risks and Diseases: Abrasions to the barbels due to sharp substrates (gravel or quartz) cause lethal secondary bacteriosis. Prolonged high temperatures weaken the immune system, favoring the onset of infections.