Alexandri|s Pearl Fish (Cynolebias alexandri) — 3-4cm

Overview

The Alexandri's Pearl Fish (Cynolebias alexandri) is a rare, expert-level annual killifish native to seasonal freshwater habitats in South America, particularly Brazil and nearby regions. Reaching 4cm in length, this peaceful species is prized for its delicate beauty, small size, and fascinating breeding cycle. As an annual killifish adapted to temporary habitats that dry seasonally, Cynolebias alexandri has a compressed life cycle and unique reproductive biology. Available for sale UK from Tropical Fish Co, this rare species rewards dedicated keepers with captivating patterns and unique behaviour in species-only aquariums.

Appearance and Coloration

Alexandri's Pearl Fish displays exquisite pearl-like colouration with a compact, slender body adorned in intricate patterns of blue, green, and yellow with iridescent pearly spots scattered across the scales. Males are intensely coloured with pronounced finnage and a bold presence, especially during courtship. The scales shimmer with a metallic lustre under subdued lighting. Females are smaller, plumper, and more subdued in colour with shorter finnage. In a planted tank with dark substrate, the pearly spots become even more visible and eye-catching.

Natural Habitat

Cynolebias alexandri inhabits seasonal freshwater habitats in South America, though the exact native range is not clearly documented. Cynolebias species are generally from seasonal freshwater habitats in Brazil and nearby regions. These temporary water bodies fill with water during the wet season and dry completely during the dry season. The water is typically soft, slightly acidic to neutral, and well-vegetated, with a substrate of mud and organic debris. During the wet season, adults spawn rapidly; as pools dry, adults perish while eggs remain dormant in dried substrate, hatching when rains return.

Aquarium Setup

A minimum 40-litre aquarium is recommended for a pair or small group of Alexandri's Pearl Fish. 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 Limnobium. 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, Cynolebias alexandri requires a varied, protein-rich diet to maintain health and colour. Offer small live and frozen meaty foods such as bloodworms, daphnia, brine shrimp, and other tiny invertebrates daily. High-quality micro pellets may be accepted after acclimation, but live and frozen foods are preferred 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

Alexandri's Pearl Fish 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 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

Cynolebias alexandri is best kept species-only to accommodate its unique breeding biology and short lifespan. Avoid large fish, aggressive fish, fast competitive feeders, fin-nippers, and shrimp or very small invertebrates that may be eaten. A calm, quiet environment is essential for this delicate annual killifish to thrive and complete its natural breeding cycle.

Breeding

This annual killifish typically breeds by laying eggs in substrate. Condition a pair or small group with high-quality live foods, then provide spawning media such as peat moss or fine sand. Provide soft, slightly acidic water and spawning substrate. Eggs often require a drying/incubation period before hatching. Collect eggs carefully and store in slightly damp peat in a sealed container. Fry hatch when the peat is re-flooded and require infusoria or newly hatched brine shrimp. Breeding success depends on careful egg management, substrate incubation, 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 Cynolebias alexandri. 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 beauty of South American annual killifish.