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Mueller's Dwarf Cichlid

Apistogramma paulmuelleri

A beautifully vibrant dwarf cichlid native to northern Peru, featuring blue-green iridescence and yellow accents. It thrives in well-structured blackwater setups with abundant leaf litter.

Taxonomy
Class:Actinopteri
Order:Perciformes
Family:Cichlidae
Subfamily:Cichlinae
Genus:Apistogramma
Species:Apistogramma paulmuelleri

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Water Temperature

22 - 30 °C

pH Value

4 - 7

Water type

Freshwater

Tank level

Bottom

Adult size

5 cm

Minimum tank volume

>= 60 L

Minimum group

>= 2

GH

2 - 10 dGH

KH

1 - 5 dKH

TDS

40 - 200 ppm

Conductivity

63 - 313 uS/cm

Species description

Geographical Origin and Habitat: Apistogramma paulmuelleri is native to the Amazon River basin in northern Peru, primarily within the Loreto Department. It inhabits slow-moving forest streams, shallow banks, and temporary ponds filled with leaf litter, fallen branches, and dense root systems.
Taxonomy and Morphology: Belongs to the Cichlidae family, subfamily Geophaginae. It was described relatively recently and is closely related to other members of the Apistogramma regani group. Genetic studies show regional variations within the Amazonian floodplains.
Social Behavior: Polygamous and territorial. Males establish territories encompassing the nesting sites of multiple females. While aggressive toward rival males, they are generally peaceful toward other non-territorial community fish that occupy the upper water columns.
Coloration and Sexual Dimorphism: Displays high sexual dimorphism. Males are larger (up to 3 inches / 7-8 cm), showing iridescent blue-green scales, yellow throat accents, and pointed dorsal and anal fins. Females are smaller (1.5-2 inches / 4-5 cm), turning bright yellow-gold with black bars when breeding.

Care, breeding and tankmates

Aquarium Setup: A minimum of 20 gallons (80 liters) is recommended for a pair or small harem. Use fine sand substrate, as they sift through it for food. Provide plenty of driftwood roots, dried oak or catappa leaves, and caves (e.g., coconut shells) for nesting.
Diet and Feeding: Carnivorous. Prefers live or frozen foods such as brine shrimp, daphnia, micro-worms, and bloodworms. They can be trained to accept high-quality slowly sinking micro-granules, but a varied meaty diet is key for health and color.
Water Quality: Demands soft, acidic water: pH 4.0-7.0 (ideally below 6.0 for breeding), GH below 5, and temperature 22-30°C (72-86°F). The addition of natural tannins from peat filtration or leaf litter is highly beneficial to mimic their blackwater habitat.
Compatibility and Cohabitation: Excellent tankmates include small tetras, pencilfish, and hatchetfish, which act as dither fish. Avoid housing them with large, aggressive tankmates or too many bottom-dwelling species like larger catfish that compete for caves.
Aquarium Breeding: Cave spawners. The female deposits eggs inside a dark cave or crevices and provides exclusive parental care for the eggs and fry. During this time, she becomes highly aggressive. Feed the newly hatched fry with fresh baby brine shrimp (nauplii).
Risks and Diseases: Highly sensitive to dissolved organic wastes and elevated nitrate levels. Poor water maintenance can lead to bacterial infections and Head and Lateral Line Erosion (HLLE) or hexamita. Regular water changes are crucial.

Geographic Origin and Distribution

Apistogramma paulmuelleri is native to the Amazon River basin in northern Peru, primarily within the Loreto Department. It inhabits slow-moving forest streams, shallow banks, and temporary ponds filled with leaf litter, fallen branches, and dense root systems.

Origin

Amazon, Orinoco, and Guianas

Fish profile

Temperament
Territorial
Overall, they exhibit a peaceful demeanor towards other species, but they are known to be territorial among their own kind. During the breeding season, both sexes become fiercely protective of their spawning sites and fry, potentially showing aggression to any intruders. Outside of breeding, they are somewhat shy and require a complex environment with plenty of hiding spaces to feel secure. Creating distinct visual barriers helps manage their territorial nature.
Diet
Carnivore
In their natural habitat, they are micro-predators that sift through the substrate for small invertebrates, insect larvae, and zooplankton. In captivity, they should be offered a varied and high-quality diet consisting of sinking micro-pellets and flakes. Supplementing their diet regularly with live or frozen foods like daphnia, baby brine shrimp, and bloodworms will promote optimal health and vibrant coloration. Variety is key to preventing nutritional deficiencies.
Sex ratio
Harem
In a suitably sized aquarium, they are best maintained in a harem configuration consisting of one dominant male and several females. If the tank is on the smaller side, maintaining a single compatible pair is the safest approach to minimize intraspecific aggression. Keeping multiple males usually requires a very large footprint with complex hardscape to break lines of sight and establish distinct territories. Proper sex ratios are vital for a peaceful tank.
Feeding frequency
Twice daily
It is highly recommended to feed them small portions once or twice daily to maintain their metabolism and overall well-being. Care must be taken to only offer an amount they can completely consume within a couple of minutes to avoid fouling the water. Overfeeding is a common mistake that can lead to severe water quality issues. Fasting the fish for one day per week can also help clear their digestive tract.
Bioload
This species has a relatively low bioload compared to larger cichlids, making it suitable for appropriately sized setups. However, they are highly sensitive to deteriorating water conditions and elevated nitrates. Maintaining pristine water quality through adequate filtration and regular water changes is absolutely crucial for their long-term health. A heavily planted tank can also help absorb excess nutrients and keep the environment stable.
Flow
Stagnant
Originating from slow-moving streams, backwaters, and sluggish tributaries, they strongly prefer gentle water flow in the aquarium. Strong currents will cause them undue stress and force them to expend unnecessary energy just to maintain their position. Filtration should be baffled if necessary to provide a calm environment, particularly near the substrate where they spend most of their time. Mimicking this natural calm flow is essential for their comfort.
Jump risk
No
Reproduction
Oviparous
They are typical cave spawners, utilizing secluded crevices, leaf litter, or natural hollows to lay their eggs. The female assumes the primary responsibility of guarding the eggs and the subsequent fry, often becoming highly reclusive. The male's role involves defending a larger peripheral territory against any perceived threats. Providing plenty of hiding spots like coconut caves, PVC pipes, and dense vegetation is critical for successful breeding.
Compatibility & tankmates
They are best kept in a species-specific aquarium or a peaceful community tank with small, non-aggressive dither fish like tetras or rasboras. Fast-swimming or boisterous tank mates should be avoided as they will easily outcompete this species for food and induce stress. Bottom-dwelling species such as Corydoras might face territorial disputes, especially if breeding behaviors commence. Careful selection of tank mates is necessary to ensure a harmonious environment.
Tank level
Bottom
These fish primarily inhabit the lower third of the water column, spending the vast majority of their day navigating the substrate. They are often seen foraging among leaf litter, driftwood, and plant roots in search of food. They rarely venture into the upper levels of the aquarium unless enticed by feeding or if they lack sufficient cover below. A well-structured bottom layout is highly appreciated.

Window to the official scientific data of the species

Data synced on: 06/15/2026

Scientific Parameters & Models

Trophic level
3.3 ± 0.4 se
Resilience
High (less than 15 months)
Phylogenetic uniqueness (PD50)
0.5
Bayesian Length-Weight
a = 0.0182, b = 2.99
VulnerabilityLow vulnerability (10 / 100)

Image gallery

Licensed images linked to the species or, when marked, to the closest representative taxon.

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Variants and close relatives

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Last updated: 06/30/2026
Mueller's Dwarf Cichlid (Apistogramma paulmuelleri) Care Guide & Tank Setup | Atlarium