White's Cynolebias (Nematolebias whitei) — 2,5-4cm

Overview

The White's Cynolebias (Nematolebias whitei), also known as the Rio Pearlfish, is a beautiful, short-lived annual killifish endemic to coastal freshwater temporary pools and floodplains in Rio de Janeiro State, Brazil. Reaching 4cm in length, this peaceful species is prized for its jewel-like colours and fascinating egg-drying breeding cycle. As an annual killifish adapted to seasonal habitats that dry completely, Nematolebias whitei has a compressed life cycle and unique reproductive biology. Available for sale UK from Tropical Fish Co, this rare species rewards dedicated keepers with spectacular colouration and captivating behaviour.

Appearance and Coloration

White's Cynolebias displays stunning jewel-like colouration with a compact, robust body adorned in vibrant blues, greens, and reds with pearl-like iridescent spots scattered across the scales. Males are intensely coloured with elongated finnage and a bold presence, especially during courtship. The fins often feature intricate patterning with red, blue, and yellow highlights that shimmer under subdued lighting. Females are smaller, plumper, and more subdued in colour with less pronounced finnage. In a planted tank with dark substrate, the colours become even more vibrant and eye-catching.

Natural Habitat

Nematolebias whitei is found in the Laguna de Araruama basin, Das Ostras River basin, and coastal plains near the mouth of São João River in Rio de Janeiro State, Brazil. These fish inhabit temporary pools and floodplains that fill with water during the wet season and dry completely during the dry season. The water is typically soft, slightly acidic, and tannin-stained, with abundant vegetation and a substrate of mud and organic debris. The annual life cycle is fundamental to the species' biology: adults spawn rapidly, then perish as pools dry, while eggs remain dormant in dried substrate until rains return.

Aquarium Setup

A minimum 40-litre aquarium is recommended for a pair or small group of White's Cynolebias. Use a fine sand or soft peat substrate to replicate the natural spawning medium. Include live plants such as Cryptocoryne, Java moss, and floating species like Salvinia or Ceratopteris. Provide spawning mops or peat moss for egg deposition. Lighting should be subdued, and filtration gentle to avoid strong currents. A secure, tight-fitting lid is essential. Maintain excellent water quality, as annual killifish are sensitive to pollution and poor conditions.

Feeding and Diet

As a carnivore, Nematolebias whitei requires a varied, protein-rich diet to maintain health and colour. Offer small live or frozen foods such as daphnia, brine shrimp, mosquito larvae, bloodworms, and other meaty microfoods daily. Use high-quality micro-pellets only as an occasional supplement, not as the staple diet. Live and frozen foods are essential for conditioning and breeding. Feed small portions twice daily, removing uneaten food promptly to maintain pristine water quality. Variety and freshness are critical for optimal health and vibrant colouration.

Behaviour and Temperament

White's Cynolebias is a peaceful species that spends most of its time exploring the lower and middle water column. Males may display to each other during courtship with flared fins and vibrant colour displays, but serious aggression is rare. These fish have a naturally short lifespan of typically 6-12 months, reflecting their annual biology. They are most active during the day and appreciate a dimly lit aquarium with plenty of cover. They are not competitive feeders, so avoid housing them with boisterous or fast-moving species.

Suitable Tank Mates

A species-only setup is best for Nematolebias whitei to accommodate its unique breeding biology and short lifespan. If tankmates are used, only very small, calm fish with identical water requirements and no competition for food should be considered. Avoid large fish, aggressive fish, fast competitive feeders, fin-nippers, and very active schooling fish. A calm, quiet environment is essential for this delicate annual killifish to thrive and complete its natural breeding cycle.

Breeding

This annual killifish lays eggs in peat or fine spawning substrate. Condition a pair or small group with high-quality live foods, then provide spawning media such as peat moss or fine sand. Eggs are buried in the substrate and usually require a dry incubation period of several weeks to months before hatching when water is reintroduced. Collect eggs carefully and store in slightly damp peat in a sealed container at room temperature. Fry hatch when the peat is re-flooded and require infusoria or newly hatched brine shrimp. Breeding success depends on careful egg management and matching seasonal conditions.

Why Buy from Tropical Fish Co

Tropical Fish Co is a trusted UK supplier of rare and specialist tropical fish, including hard-to-find annual killifish species like Nematolebias whitei. We guarantee healthy, well-conditioned stock, expert care advice, and secure nationwide delivery. Every fish is quarantined and inspected before dispatch, ensuring you receive only the finest specimens. Whether you're setting up a dedicated killifish tank or adding a rare species to your collection, Tropical Fish Co offers unmatched quality and customer service. Order online today and experience the fascinating world of Brazilian annual killifish.