Amatitlania myrnae

The Topaz Cichlid, also known as Myrna's or the Sapphire Cichlid, is a stunning fish from Central America that packs a big personality into a small body. While its shimmering blue and yellow colours are captivating, it's not a typical peaceful community fish. It belongs to the cichlid family, famous for their intelligence and bold, territorial nature. Think of them as the small guard dogs of the aquarium world; they will claim a part of the tank as their own and defend it, especially from other bottom-dwelling fish.

For a happy Topaz Cichlid, you'll need an aquarium of at least 80 litres, which gives a pair enough space to establish their home. They love to rearrange their environment, so a sandy bottom is perfect for their natural digging behaviour. Provide plenty of caves, rocks, and driftwood for them to explore and hide in. Be warned, they are known as 'plant rooters,' meaning they will likely uproot delicate aquarium plants. It's best to choose very tough plants like Anubias and Java Fern attached to decorations, or simply use high-quality artificial plants.

Feeding is easy as they are omnivores and will accept most fish foods. A good quality pellet or flake food should be their main diet, with occasional treats of frozen or live foods and some vegetable matter like blanched peas to keep them healthy.

Because of their territorial behaviour, choosing tank mates requires care. They are best kept as a single breeding pair. If you want other fish, choose fast-swimming species that stay in the upper parts of the water and can handle a bit of chasing. A Topaz Cichlid is a fascinating and rewarding pet for an aquarist prepared for its dynamic personality.

The Topaz Cichlid, Amatitlania myrnae, is a captivating dwarf cichlid hailing from the slow-moving, warm, and alkaline river systems of the Atlantic slope in Costa Rica and Panama. Its common names, 'Topaz' and 'Sapphire,' aptly describe the beautiful iridescent sheen that adorns its flanks, which intensifies dramatically during courtship and breeding displays. As a member of the Amatitlania genus, it shares many behavioural traits with its ubiquitous cousin, the Convict Cichlid (A. nigrofasciata), but is generally smaller and considered by many hobbyists to be slightly less aggressive, though this is highly relative. It remains a classic territorial cichlid, full of interactive and engaging behaviours.

Creating a suitable habitat is key to observing its natural tendencies and reducing stress. An 80-litre aquarium is the absolute minimum for a single breeding pair, but a larger tank of 120 litres or more is recommended to better manage territorial disputes. A biotope-inspired aquascape is ideal. Use a fine sand substrate to accommodate their innate desire to dig ('plant rooting'), which is a foraging and nest-building behaviour. Complex structures built from smooth river stones, caves, and tangled driftwood are essential. These elements not only provide security but also create crucial sightline breaks, which are vital for mitigating aggression, particularly within a pair or towards tank mates. Due to their digging, delicate rooted plants are ill-advised. Instead, aquarists should opt for robust epiphytes like Anubias barteri, Microsorum pteropus (Java Fern), and Bolbitis heudelotii attached firmly to the hardscape.

Selecting companions requires strategic planning. Avoid other bottom-dwelling or similarly shaped cichlids unless the aquarium is exceptionally large (upwards of 200 litres) with abundant hiding spots. The best tank mates are fast, robust dither fish that occupy the middle to upper water column, such as larger characins or swordtails that thrive in similar hard water conditions. It is crucial to introduce any dither fish to the aquarium before the cichlid pair has fully established their territory.

Breeding is a fascinating spectacle. A. myrnae are substrate spawners and form strong, monogamous pair bonds. Courtship involves intense displays and the mutual cleaning of a chosen spawning site, typically a flat stone or the inside of a cave. Once eggs are laid, both parents engage in rigorous biparental care, fanning the eggs and fiercely defending their territory. Aggression peaks during this period, and any tank mates will be at risk. The fry, once free-swimming, are diligently herded and protected by the parents. A varied diet is crucial for health and colouration. A high-quality cichlid pellet should form the staple, supplemented regularly with protein from frozen brine shrimp, mysis, and daphnia, and essential vegetable matter like spirulina flakes or blanched zucchini to aid digestion and mimic their natural omnivorous diet. Its Vulnerable (VU) conservation status in the wild highlights the importance of responsible captive breeding, preserving this gem for future generations of aquarists.

Amatitlania myrnae (Loiselle, 1997) is a freshwater fish of the Cichlidae family, endemic to Central American river systems. Its natural habitat consists of low-flow, lentic environments within Atlantic slope drainages of Costa Rica and Panama. The provided water chemistry parameters—pH 7.0-8.0, water hardness of 90-350 ppm, and TDS around 300—are indicative of the limestone-rich geology of this region, resulting in mineral-rich, alkaline waters.

Morphologically, A. myrnae exhibits the archetypal laterally-compressed, ovoid body shape characteristic of the genus Amatitlania. Its common names refer to its distinctive nuptial coloration, where iridophores in the dermis produce striking blue and yellow hues, a sexually selected trait that intensifies during reproductive periods to signal fitness to potential mates.

Ecologically, the species occupies the middle and bottom strata of the water column. Its classification as a 'plant rooter' describes a key foraging behavior known as substrate sifting. A fine-particle substrate in captivity is therefore recommended to facilitate this natural searching for invertebrates and organic detritus. This behavior is coupled with its territoriality, a fundamental aspect of its behavioral ecology. In its natural environment, and replicated in aquaria, A. myrnae establishes and defends a territory centered around a preferred shelter or future spawning site. The minimum tank size of 80 liters reflects the spatial requirement to accommodate this resource-defense behavior and mitigate the high levels of intraspecific aggression characteristic of breeding pairs.

Reproductive strategy is biparental substrate spawning. The 'moderate' breeding difficulty rating suggests that while pair formation and spawning are readily achieved under correct environmental cues (stable, warm temperatures of 24-30°C and appropriate water chemistry), the primary management challenge is the significant increase in parental aggression. This heightened defense of offspring is a successful evolutionary strategy but requires careful management in a closed system.

Physiologically, the species' medium metabolism, oxygen consumption, and waste production rates, quantified by a bioload factor of 3.8, necessitate robust and mature biological filtration systems. An aquarist must maintain stringent water quality management to process the nitrogenous wastes and prevent the accumulation of nitrates. The omnivorous diet necessitates a formulation that balances animal protein with fibrous plant matter to ensure proper gastrointestinal function and prevent conditions such as bloat. The IUCN status of Vulnerable (VU) underscores the ecological pressures on its wild populations, primarily from habitat degradation, and places a conservation responsibility on the aquatics community to maintain genetically sound and pure ex-situ populations, avoiding hybridization with congeners like A. nigrofasciata.