Dwarf Corydoras

Corydoras hastatus is one of three recognised pygmy cories (alongside C. pygmaeus and C. habrosus) that have adopted a semi-pelagic lifestyle, routinely schooling in the water column rather than remaining on the substrate. At a maximum size of 2.5 cm it is one of the smallest vertebrates commonly kept in the hobby and is ideal for nano or heavily planted aquaria.

Native to the Amazon basin in Brazil and Bolivia, it inhabits shallow, clear or slightly stained streams with sandy bottoms and dense aquatic vegetation. In the aquarium it hovers in mid-water, constantly in motion, and can cover large distances in a tight, coordinated school — a captivating behaviour that distinguishes it from most other bottom-dwelling catfish.

Care is straightforward provided the tank is stable and appropriately sized food is offered. Micro-granules, baby brine shrimp, and powdered sinking foods are all accepted. Keep in groups of at least ten to see the schooling behaviour at its best, and combine only with species too small or gentle to harass it.

Water: Soft to moderately hard, pH 6.0–7.5, temperature 22–26°C; stable conditions important for small body mass. Tank: 30 L nano or larger; fine sand bottom, dense planting, and very gentle filtration flow. Feeding: Micro-granules, powdered sinking wafer, baby brine shrimp, and finely ground frozen bloodworm. Breeding: Documented in aquaria; eggs laid on plant leaves; small water change with cooler water as trigger. Compatibility: Ideal with microrasboras, pygmy tetras, small livebearers, and peaceful shrimp species.