Foirni Checkerboard Cichlid
Dicrossus foirni
The precious and very rare 'Rio Negro Checkerboard Cichlid' (5-7 cm). Less common than its cousin D. filamentosus, the Dicrossus foirni is a tiny cylindrical jewel originating from the extreme Brazilian blackwaters. It is distinguished by its slightly more robust build and, above all, by the irregular checkerboard pattern that often merges into double broken lateral bands. Lacking the formidable lyre tail of the filamentosus, the male shows off a finely rounded lanceolate caudal fin with blue reflections. Severely delicate, it demands housing in sterile, hyper-acidic (pH < 5.5) and tannin-saturated waters.
Water Temperature
25 - 29 °C
pH Value
4.5 - 6.5
Water type
Freshwater
Tank level
Bottom and middle
Adult size
9 cm
Minimum tank volume
>= 100 L
Minimum group
>= 1
GH
1 - 5 dGH
KH
1 - 2 dKH
TDS
25 - 95 ppm
Conductivity
39 - 148 uS/cm
Species description
Geographical Origin and Habitat: Middle and upper Rio Negro basin, in Brazil. Inhabits ultra-acidic waters (pH below 5), surrounded by piles of wood and roots in flooded rainforest rivers.
Taxonomy and Morphology: Foirni's Checkerboard Cichlid (Dicrossus foirni). Often labeled as Dicrossus sp. "Rio Negro" in the past. It is the most massive and voluminous species of the genus Dicrossus.
Social Behavior: Relatively shy, moves constantly but jerkily among the dead leaves. Being larger than the "filamentosus", males can show themselves moderately intolerant towards conspecifics if space is scarce.
Coloration and Sexual Dimorphism: Gorgeous. Beige background covered by "checkerboard spots", but in foirni the checkerboards tend to partially merge or are framed by incredible metallic blue and blood red reflections on males. Round tail, not lance or fork-shaped.
Care, breeding and tankmates
Aquarium Setup: Long aquarium required (at least 100 cm / 40 inches). White silica sand, woods of intricate branches (manzanita wood), abundant leaf litter and total absence of intense lighting. Add alder cones for tannin.
Diet and Feeding: They need a weaning phase. Offer Grindal worms, fine bloodworms and brine shrimp (live or very high quality frozen). Once acclimatized, they are able to collect micro-pellet food from the bottom.
Water Quality: "Blackwater Extreme" fish. Stable temperature (27-28°C / 81-82°F), pH between 4.0 and 5.5, non-existent hardness and conductivity close to 10 µS. Nitrates must be absolute 0.
Compatibility and Cohabitation: Ideal companions are small characins (Hemigrammus bleheri, Paracheirodon axelrodi) and surface fish. Strongly not recommended other bottom cichlids so as not to crack its reserved psyche.
Aquarium Breeding: A real milestone for the demanding aquarist. They lay on catappa leaves. The female becomes a protective fury and will assume war coloration. Very delicate eggs subject to fatal mold if the pH rises above 5.
Risks and Diseases: Sensitivity to "fresh water" pathogens. In Blackwater rivers the bacterial load is zero. In aquariums without tannins or with high GH/KH, they are quickly decimated by skin ulcers and dropsy.
Geographic Origin and Distribution
Middle and upper Rio Negro basin, in Brazil. Inhabits ultra-acidic waters (pH below 5), surrounded by piles of wood and roots in flooded rainforest rivers.
Origin
Amazon, Orinoco, and Guianas
Fish profile
- Temperament
- Semi-aggressive
- Dicrossus foirni possesses a profoundly peaceful, shy, and retiring temperament. They are easily startled and require an environment with subdued lighting and numerous hiding spots to feel secure. When kept in a suitable biotope with gentle companions, they are fascinating to observe as they carefully explore their territory. They are an advanced-level fish that requires a dedicated aquarist willing to meet their stringent environmental and dietary demands.
- Diet
- Omnivore
- They are strict micro-predators that feed heavily on tiny crustaceans and benthic invertebrates in their natural habitat. In the aquarium, they require a varied diet of small, meaty live or frozen foods to survive and thrive. Daily offerings of newly hatched brine shrimp, daphnia, and finely chopped bloodworms are essential for their nutritional needs. They will almost certainly refuse dry flakes or pellets, making them a demanding species to feed.
- Life expectancy
- 3-5 years
- In captivity, Dicrossus foirni typically lives for 3 to 5 years under optimal care conditions. Achieving this lifespan requires maintaining extremely stable and clean water parameters, as they are highly sensitive to sudden changes and chemical fluctuations. A well-established aquarium with a mature biological filter is critical to prevent premature mortality. Proper diet and stress reduction through adequate hiding spots also play a major role in their longevity.
- Adult size
- 9 cm
- The catalog's scalar value is 9 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 7.09 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Dicrossus foirni (v25.04); male or unsexed record. These figures are not interchangeable: the first is the profile's editorial reference, whereas the second is a published maximum under a specific measurement convention; differences among sources can reflect sex, population, life stage and measuring method.
- Sex ratio
- Harem
- They are best maintained in a harem configuration consisting of one male and several females (ideally three or more). This structure mimics their natural social dynamics and prevents the male from aggressively pursuing a single female to exhaustion. Multiple males should only be kept if the aquarium is exceptionally large with numerous broken lines of sight to establish separate territories. A proper sex ratio is crucial to maintaining a peaceful and stress-free environment.
- Feeding frequency
- Twice daily
- Due to their small digestive tracts and active foraging behavior, they require multiple small feedings throughout the day. Providing two to three small meals daily ensures they receive enough calories without fouling the water with uneaten food. Because they are slow, deliberate eaters, care must be taken to ensure they are not outcompeted by faster tank mates. Target feeding with a pipette may be required to ensure they receive adequate nutrition.
- Bioload
- Low to Medium
- Like other species in its genus, Dicrossus foirni produces a very minimal bioload, making it manageable for smaller setups. However, their extreme intolerance to any buildup of nitrogenous waste means pristine water quality is absolutely non-negotiable. They require a fully mature, stable aquarium with highly efficient biological filtration. Rigorous maintenance, including frequent small water changes with reverse osmosis water, is essential to keep them healthy.
- Flow
- Stagnant
- Endemic to the slow-moving, tannin-rich blackwater environments of the Rio Negro basin, they demand almost stagnant water conditions. Strong water flow will rapidly exhaust them and prevent them from engaging in natural foraging behaviors. Filtration should be very gentle, ideally utilizing a mature sponge filter or a heavily baffled canister filter. Creating a calm, serene aquatic environment is critical for their long-term survival in captivity.
- Reproduction
- Oviparous
- Breeding D. foirni is exceptionally challenging, requiring extremely acidic (pH 4.0-5.5) and soft water to simulate their natural breeding grounds. They are substrate spawners that lay their eggs discreetly on broad leaves or hidden hardscape elements. The female takes sole responsibility for guarding the clutch and the ensuing fry, becoming highly territorial during this period. The minuscule fry are highly sensitive and require immediate feeding with infusoria or rotifers.
- Compatibility & tankmates
- They are a highly delicate and peaceful dwarf cichlid that must only be housed with similarly gentle, small tank mates. Excellent companions include small tetras like the Cardinal or Green Fire Tetra, and peaceful bottom dwellers like small Corydoras species. Fast, boisterous, or aggressive fish will easily outcompete them for food and cause severe, often fatal, stress. They do best in a species-only biotope or a carefully curated, tranquil South American community.
- Tank level
- Middle/Bottom
- They are definitively bottom-dwellers, intimately associating with the substrate and low-lying hardscape. A soft, sandy bottom scattered with a thick layer of dried botanical leaves is absolutely essential for their comfort and natural behavior. They spend their days meticulously inspecting the leaf litter for microscopic food items. They will only venture into the mid-water column momentarily, quickly returning to the safety of the substrate.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.2 ± 0.5 se
- Phylogenetic uniqueness (PD50)
- 0.5312
- Bayesian Length-Weight
- a = 0.00724, b = 3.13
- VulnerabilityLow vulnerability (10 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
Related species
Recommendations grouped by close relatives, companion choices, and similar care.
