Singhalese Panchax (Aplocheilus dayi) — 5-6cm

Overview

The Singhalese Panchax (Aplocheilus dayi), also known as the Ceylon Killifish, is a striking Sri Lankan surface-dwelling killifish endemic to the island's freshwater habitats. Reaching up to 9cm in length, this semi-aggressive species is renowned for its bold personality, iridescent colouration, and fascinating breeding behaviour. Ideal for covered, planted aquariums with peaceful tankmates, Aplocheilus dayi thrives in warm, soft to moderately hard water with gentle filtration. Available for sale UK from Tropical Fish Co, this rare killifish rewards experienced keepers with a captivating surface predator that commands attention in any aquarium.

Appearance and Coloration

The Singhalese Panchax displays striking colouration with a slender, elongated body adorned in shimmering greens, blues, and golds. Both males and females feature a distinctive black dot at the rear end of the base of the dorsal fin, a key identification feature. Males are more intensely coloured than females, with more pronounced finnage and a bolder presence. The scales shimmer with a metallic lustre under subdued lighting, and the large, upturned mouth is perfectly adapted for surface feeding. Females are plumper and more subdued in colour, especially when gravid.

Natural Habitat

Aplocheilus dayi is endemic to Sri Lanka (Ceylon), where it inhabits slow-moving streams, ponds, ditches, and rice paddies. These waters are typically warm, soft to moderately hard, and well-vegetated, with abundant floating plants and surface cover. The substrate consists of mud, sand, and organic debris, and water flow is minimal. During the monsoon season, these fish spawn among fine-leaved plants or submerged vegetation, producing 50-150 eggs per female.

Aquarium Setup

A minimum 60-litre aquarium is recommended for a pair or small group of Singhalese Panchax. Use a fine sand or smooth gravel substrate with plenty of live plants such as Vallisneria, Cryptocoryne, Java moss, and floating species like Pistia or Salvinia. Provide open swimming space near the surface, as this is a surface-oriented species that spends most of its time hunting at the water's surface. Filtration should be gentle to avoid strong currents. A secure, tight-fitting lid is essential, as this surface-dwelling fish can jump.

Feeding and Diet

As a carnivore, Aplocheilus dayi requires a varied diet of quality floating micro-pellets, frozen or live insect foods such as mosquito larvae, daphnia, brine shrimp, and small worms. Occasional small crustaceans and other meaty foods are also appreciated. This surface-oriented predator is well-adapted to capturing live prey at the water's surface, so live foods are ideal for maintaining condition and colour. Feed small portions once or twice daily, removing uneaten food promptly to maintain water quality.

Behaviour and Temperament

The Singhalese Panchax is a semi-aggressive, surface-dwelling species with a bold personality. Males may be territorial towards each other, especially in smaller tanks, and these fish are adept predators that may eat very small fish fry or nano fish. However, they are generally peaceful towards fish of similar size that occupy the middle and bottom of the tank. Most active during dawn and dusk, they spend much of their time patrolling the surface in search of food.

Suitable Tank Mates

Suitable companions include small to medium peaceful fish that occupy the middle and bottom of the tank, such as fast-moving danios and rasboras of similar size, and peaceful bottom dwellers like small loaches or catfish that are not tiny enough to be eaten. Non-aggressive shrimp may be kept in larger, well-planted tanks, though juveniles may be at risk. Avoid very small fish fry, nano fish, slow long-finned fish, aggressive or highly territorial species, and tiny shrimp or small invertebrates that may be preyed upon.

Breeding

Eggs are typically laid among fine plants or spawning mops, with females producing 50-150 eggs. Remove adults if you want to protect eggs, as they may eat them. Raise fry on infusoria, microworms, and newly hatched brine shrimp. Breeding is straightforward in well-conditioned adults, and a separate breeding setup with soft, slightly acidic water and fine-leaved plants or spawning mops improves success rates. Fry grow quickly and can be raised to adulthood in a well-maintained grow-out tank.

Why Buy from Tropical Fish Co

Tropical Fish Co is a trusted UK supplier of rare and specialist tropical fish, including hard-to-find killifish species like Aplocheilus dayi. 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 bring the beauty of Sri Lankan waters into your home aquarium.