Mangrove Rivulus

Kryptolebias marmoratus is a killifish notable for its biology. Most individuals are hermaphrodites that produce both eggs and sperm and can fertilize their own eggs inside the body; because of this, even a single fish can lay eggs. Males also exist but are rare. It lives in crab burrows and rotting logs in mangroves; when the water recedes it can survive out of water for weeks in a damp environment. It is recognized by its spotted, brown-olive body and the eye-like spot at the base of the tail.

• 30 liters for a single individual; more than one individual only in a divided, spacious aquarium.
• Brackish water: a salinity of about one third of seawater is suitable; it also tolerates fresh and saltier water.
• Roots, pieces of log, shallow areas and spots that rise above the water surface.
• The lid must cover every gap; it can climb out over the glass and along hoses.

Carnivorous. It is fed brine shrimp, mysis shrimp, bloodworms and small crustaceans; it may also accept granules.

Rough and territorial towards its own species; it is usually kept alone. It lives near the bottom among hiding places and often leaves the water to rest on wet surfaces.

Good companions: best kept alone; because it needs brackish water, it cannot be kept with freshwater species.

Avoid: a second individual of its own species (in a small aquarium), freshwater community fish, large fish.