Orinoco Flag Cichlid
Mesonauta insignis
The reticulated 'Orinoco Flag Cichlid' (10-15 cm). Very often confused in the trade with M. festivus, the Mesonauta insignis represents its Orinoco/Rio Negro variant. It shares the magnificent pointed discoid anatomy and the pelagic surface habits. Shy and elegant, it exhibits a dense dark reticulation on the dorsal scales. Ideal in a group, it is a fantastic inhabitant of the aquatic canopy of Blackwater style planted aquariums.
Water Temperature
25 - 30 °C
pH Value
5.5 - 7
Water type
Freshwater
Tank level
Surface and middle
Adult size
15 cm
Minimum tank volume
>= 180 L
Minimum group
>= 1
GH
1 - 8 dGH
KH
1 - 4 dKH
TDS
25 - 160 ppm
Conductivity
39 - 250 uS/cm
Species description
Geographical Origin and Habitat: Upper Orinoco and Rio Negro basin (Colombia, Venezuela, Brazil). Typical species of the true "Blackwaters", where it inhabits flooded forests and banks dense with fallen branches and lianas.
Taxonomy and Morphology: Orinoco Festivum (Mesonauta insignis). Very similar to festivus. Features the same compressed triangular morphology and filiform pelvic receptors. Often incorrectly sold under the name "M. festivus".
Social Behavior: Timid gregarious. Spends much of its time suspended motionless obliquely among the roots (camouflage), ready to dart to catch small insects. Has a cautious and exploratory swimming style.
Coloration and Sexual Dimorphism: Differs from festivus by the dorsal pattern: M. insignis has strongly marked/reticulated dorsal scales ("net" pattern visible above the diagonal black stripe). The overall livery is more yellow/brown, typical of blackwater fish.
Care, breeding and tankmates
Aquarium Setup: Orinoco biotope tank. Minimum 120 cm (48 inches). Very dim light or obscured by thick floating plants (Limnobium). Fine sand substrate covered with oak or catappa leaves. Dry manzanita branches inserted from above.
Diet and Feeding: Surface/mid-water omnivore. Excellent eater of mosquito larvae, drosophila (fruit flies thrown on the surface), protein flakes and occasionally pieces of blanched zucchini.
Water Quality: More demanding than festivus. Requires decidedly warm water (26-29°C / 79-84°F), very soft (very low GH) and strictly acidic (Ph 5.5-6.5). Amber water rich in humic acids is almost vital for its reproduction and long-term health.
Compatibility and Cohabitation: Peaceful and delicate cichlid. Perfect roommate for Symphysodon (Discus), Pterophyllum altum (Altum Angelfish), Uaru and schools of Cardinals or Rummy-nose (if not too small). Avoid any snappy fish.
Aquarium Breeding: Difficult, as it requires perfect water chemistry. The pair spawns on woods or roots near the surface. Parents scrupulously care for the fry for weeks, guiding them in a group through the vegetation.
Risks and Diseases: Lateral Line Infections (HITH). Very prone to "Hole in the Head" disease if kept in hard waters or with poor hygiene (nitrate accumulation). Lack of minerals or adequate filtration will cause fatal craters on the head.
Geographic Origin and Distribution
Upper Orinoco and Rio Negro basin (Colombia, Venezuela, Brazil). Typical species of the true "Blackwaters", where it inhabits flooded forests and banks dense with fallen branches and lianas.
Origin
Amazon, Orinoco, and Guianas
Fish profile
- Temperament
- Semi-aggressive
- They are generally peaceful and shy. They can become territorial during spawning. They behave very well in community setups.
- Diet
- Omnivore
- They are naturally omnivorous. They prefer plant matter and small invertebrates. Spirulina flakes and frozen foods are excellent choices.
- Life expectancy
- 7-12 years
- In a well-maintained aquarium, the flag cichlid can live between 7 and 12 years. Their lifespan is maximized by keeping water clean, low in nitrates, and slightly acidic to mimic their natural blackwater habitats. High-quality food and a peaceful environment are also key factors in ensuring their health and longevity.
- Adult size
- 15 cm
- The catalog's scalar value is 15 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 12.4 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Mesonauta insignis (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
- Pair
- They are best kept in established pairs. Groups require very large aquariums. Sexing juveniles is notably difficult.
- Feeding frequency
- Twice daily
- Feed them once or twice daily. They are careful and deliberate eaters. Ensure fast fish don't outcompete them.
- Bioload
- Medium
- They produce a typical moderate bioload. Efficient filtration easily handles their waste. Regular maintenance keeps the environment pristine.
- Flow
- Stagnant
- They prefer gentle water flow. Avoid excessively strong currents. Calm surfaces provide an ideal, stress-free environment.
- Reproduction
- Oviparous
- They are monogamous substrate spawners. They lay eggs on flat broad leaves. Both parents actively guard the fry.
- Compatibility & tankmates
- They are peaceful community cichlids. Suitable tank mates include tetras and corydoras. Avoid very small fish that fit their mouths.
- Tank level
- Top/Middle
- They occupy the middle and upper levels. They appreciate tall plants for hiding. They often rest near floating vegetation.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.4 ± 0.51 se
- Resilience
- High (less than 15 months)
- Phylogenetic uniqueness (PD50)
- 0.5078
- Bayesian Length-Weight
- a = 0.02951, b = 3.02
- 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.
