Constanciae killifish

Care at a glance

Overview

This is a small, seasonal killifish best kept as a pair or a small group in its own tank, since it is easily out-competed and shows to best effect among its own kind. Males are mostly peaceful but display and spar, so give a planted, gently cool tank with soft water and cover to break up sight lines. Choose tankmates, if any, with caution, keeping to small, calm, soft-water fish or none at all. Feed small live and frozen foods, which suit it far better than dry flake: daphnia, brine shrimp, grindal worm, and frozen bloodworm. A tank of around 40 litres is enough for a pair or trio.

In the wild

It lives in seasonal pools on the coastal plain of Rio de Janeiro state in Brazil, temporary blackwater habitats that fill in the wet season and dry out later in the year. Recreate that with soft, gently cool water of 20 to 25 degrees Celsius and an acidic to neutral pH of 5.5 to 7.0, over a dark substrate or peat, with fine plants and leaf litter for cover.

Good to know

It belongs to the family Rivulidae, the New World killifishes, and reaches about 6 cm, the males finned and patterned as pearlfish. It is an annual: in the wild the adults die as their pool dries, leaving drought-resistant eggs buried in the substrate that hatch when rain returns. Breeding follows that cycle and is of moderate difficulty, needing a peat spawning medium and a dry resting period for the eggs.

Did you know

Its eggs outlast the pool it lives in. A breeding pair dives into the soft bottom to spawn, and the buried eggs survive months of drought in damp substrate, waiting for the next rains before the fry emerge.

Common questions

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