Gladicauda Checkerboard Cichlid
Dicrossus gladicauda
The lethal and beautiful 'Sword-Tailed Checkerboard Cichlid' (5-6 cm). Originating from the acidic hell of the Rio Atabapo, the Dicrossus gladicauda is the most extreme, smallest and fascinating member of its family. It shares the cigar shape and the checkerboard of its cousin filamentosus, but the male possesses an invaluable distinguishing trait: an upper prolongation of the caudal fin long and sharp as a lance or a "sword" (hence gladi-cauda). Severely intolerant and hyper-delicate, it is the ultimate Grail for aquarists specialized in extreme blackwater biotopes.
Water Temperature
25 - 29 °C
pH Value
4.5 - 6.5
Water type
Freshwater
Tank level
Bottom and middle
Adult size
7 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: Colombia, restricted to the Rio Atabapo basin. Very dark water streams (Blackwater), acidic, shady, overflowing with submerged timber and sandy quartz bottoms covered with leaves.
Taxonomy and Morphology: Swordtail Checkerboard Cichlid (Dicrossus gladicauda). Takes its common and Latin name ("gladicauda" = sword tail) from the male's tail, which develops a single long asymmetrical filament in the upper lobe, like a sword.
Social Behavior: Peaceful, but males are competitive in cramped tanks. They live mostly sifting the substrate on their own. Ideally, 1 male and several females or schools of juveniles are recommended.
Coloration and Sexual Dimorphism: Males (spectacular) have 2 parallel rows of square black spots, reddish reflections on the anal and dorsal fins and the iconic asymmetric blue/red "sword" on the tail. Simpler females, with 3 prominent black spots.
Care, breeding and tankmates
Aquarium Setup: The water must be the color of dark tea (intense tannins). Very white sand, Indian almond leaves (Catappa) and an immense interweaving of woods. Any intense light must be shielded with Limnobium.
Diet and Feeding: Feeding rhythms are slow. Provide live (brine shrimp nauplii, Moina) and very small frozen food. Tends to ignore classic dry feeds for days during acclimatization.
Water Quality: Zero chemical tolerance. To see its colors the water must have a total hardness of less than 2-3 dGH and a pH well below 6.0 (the target is 5.0). Tolerated Nitrites/Nitrates = ZERO.
Compatibility and Cohabitation: Compatible only with tiny schooling characins from black waters that tolerate the same extreme care (e.g. small Nannostomus). Absolutely forbidden turbulent Loricariids or Corydoras.
Aquarium Breeding: Rarely reported. Lowering the values (pH to 4.5 and very low TDS) stimulates courtship. They lay on a leaf on the bottom fiercely protected by the tiny female.
Risks and Diseases: Dropsy from stress and bloat if overfed with tubifex or foods rich in polluted blood. Very high loss rate in the first 15 days after transport (imported fish).
Geographic Origin and Distribution
Colombia, restricted to the Rio Atabapo basin. Very dark water streams (Blackwater), acidic, shady, overflowing with submerged timber and sandy quartz bottoms covered with leaves.
Origin
Tropical oceans and reefsExtra-Amazon South AmericaEast Asia
Fish profile
- Temperament
- Semi-aggressive
- Dicrossus gladicauda is an incredibly shy, peaceful, and fragile species that demands a serene environment. They are easily stressed by sudden movements, bright lights, or boisterous tank mates, responding by hiding continuously and losing color. When kept in a dedicated blackwater setup tailored to their needs, they exhibit deliberate, graceful movements and fascinating foraging behaviors. They are a true specialist fish that should only be kept by those dedicated to their specific requirements.
- Diet
- Omnivore
- D. gladicauda are obligate micro-predators that naturally forage for microscopic life among submerged leaf litter. Their captive diet must heavily feature small live or frozen foods, such as baby brine shrimp, daphnia, and cyclops, to ensure they receive proper nutrition. They are notoriously picky eaters and will likely ignore prepared dry foods like flakes or standard pellets. Persistence and a variety of high-quality frozen or live offerings are required to keep them well-fed and vividly colored.
- Life expectancy
- 3-5 years
- In a well-managed aquarium, Dicrossus gladicauda typically lives for 3 to 5 years under optimal care. Their lifespan is highly dependent on water quality, as they are very sensitive to nitrogenous waste and sudden shifts in water chemistry. A mature filter system and routine, small water changes are essential to prevent premature mortality. Providing a low-stress environment with appropriate shelter and a high-quality diet will also help maximize their lifespan.
- Adult size
- 7 cm
- The catalog's scalar value is 7 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 4.24 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Dicrossus gladicauda (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
- To promote natural behavior and reduce stress, they are best kept in a harem of one male to three or four females. This prevents the male's reproductive advances from overwhelming a single female, distributing his attention across the group. Keeping multiple males is generally ill-advised unless the aquarium is extremely large and complexly decorated to allow for separate territories. A female-heavy ratio is the key to maintaining harmony in their delicate social structure.
- Feeding frequency
- Twice daily
- They possess small digestive systems and require multiple, small feedings distributed throughout the day. Feeding them two to three times daily with appropriate micro-foods is necessary to sustain their health and energy levels. Care must be taken to ensure the food reaches the bottom where they forage, without being intercepted by mid-water tank mates. Overfeeding must be strictly avoided, as decomposing food will quickly ruin the pristine water quality they require.
- Bioload
- Low
- Like its congeners, Dicrossus gladicauda produces a remarkably low bioload, suitable for carefully managed, small to medium aquariums. Despite their small impact on waste levels, they possess zero tolerance for ammonia, nitrite, and elevated nitrates. The aquarium must be fully established with impeccable biological filtration to maintain the pristine conditions they demand. Consistent, meticulous maintenance and use of reverse osmosis water to maintain soft, acidic conditions are paramount.
- Flow
- Stagnant
- Originating from sluggish, blackwater habitats, they require near-still water conditions in the aquarium. Strong filtration currents will severely stress them, forcing them to expend vital energy just to maintain their position. Gentle filtration via a mature sponge filter is usually the best choice to provide biological filtration without creating turbulent water movement. The environment should replicate a calm, slow-moving jungle stream.
- Reproduction
- Oviparous
- Breeding this species is an extreme challenge reserved for highly experienced aquarists, requiring meticulously soft, acidic water (pH 4.0-5.0). They are secretive substrate spawners, laying small clutches of eggs in secluded crevices or on hidden leaves. The female provides intensive maternal care, aggressively guarding the eggs and fry from any perceived threats, including the male. The fry are incredibly small and require continuous feeding with the smallest available foods, such as infusoria, to survive their first weeks.
- Compatibility & tankmates
- This delicate dwarf cichlid is entirely unsuited for a general community tank and requires exceptionally peaceful companions. They thrive when kept alongside tiny, non-aggressive species such as dwarf rasboras, pencilfish, or the smallest corydoras species. Aggressive, fast-swimming, or significantly larger fish will quickly outcompete them for food, leading to starvation and stress-induced illness. A species-only setup or a very carefully planned blackwater biotope is the safest approach for their long-term health.
- Tank level
- Middle/Bottom
- They are strict bottom-dwellers, spending nearly all their time hovering just above the substrate or navigating through leaf litter. A soft, sandy substrate is mandatory, heavily decorated with botanical items like catappa leaves, alder cones, and intricate driftwood. They rely on this complex benthic environment for shelter, foraging, and spawning sites. They will rarely, if ever, utilize the upper portions of the water column.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.2 ± 0.4 se
- Resilience
- High (less than 15 months)
- 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.
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Recommendations grouped by close relatives, companion choices, and similar care.
