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True Rummy-Nose Tetra

Hemigrammus rhodostomus

The *Hemigrammus rhodostomus* is the 'True' Rummy-Nose Tetra, often confused in the aquarium trade with the almost identical and more widespread *H. bleheri* (the common Rummy-nose) and the *Petitella georgiae* (False Rummy-nose). It is distinguished from the Bleheri by the red coloration of the snout which is strictly confined to the head and DOES NOT extend beyond the gills, and by the presence of a faint dark line running along the caudal peduncle until it merges with the spectacular black and white zebra stripes of the caudal fin. Slightly larger than the Bleheri (up to 5-6 cm / 2.5 inches) and with a more silvery body, it is a tireless pelagic swimmer and one of the most cohesive and spectacular schooling fish that can be hosted in large South American aquariums.

Taxonomy
Class:Actinopteri
Order:Characiformes
Family:Characidae
Genus:Hemigrammus
Species:Hemigrammus rhodostomus

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Water Temperature

24 - 28 °C

pH Value

5.5 - 7

Water type

Freshwater

Tank level

Middle

Adult size

5 cm

Minimum tank volume

>= 120 L

Minimum group

>= 10

GH

1 - 10 dGH

KH

1 - 5 dKH

TDS

25 - 200 ppm

Conductivity

39 - 313 uS/cm

Species description

Geographical Origin and Habitat: Lower Amazon River Basin in Brazil. Compared to the Bleheri ("false" Rummy), the Rhodostomus inhabits areas further downstream, in clear but peaty rivers (Clear/Black water mix).
Taxonomy and Morphology: True Rummy-Nose Tetra (Hemigrammus rhodostomus). Slender, with hypnotic swimming. The main characteristic to distinguish it from the bleheri is that the red coloring NEVER extends beyond the gills.
Social Behavior: Like their cousins, they are slaves to the school (extreme Shoaling Fish). A single H. rhodostomus or in a microscopic group (3 fish) stops swimming in open waters to hide behind filters until it dies of starvation.
Coloration and Sexual Dimorphism: Tip of the snout stained with cherry, with a semi-transparent silver body and a conspicuously zebra-striped tail (black-white). In females the abdomen is increasingly "square" towards the bottom due to the ovarian sacs.

Care, breeding and tankmates

Aquarium Setup: Classic rectangular aquarium (minimum 80-100 cm / 32-40 inches). They obligatorily need a dense back side full of plants (Cabomba, Myriophyllum) to give them the security of diving for cover, but the front 70% of the tank must be empty for frantic swimming.
Diet and Feeding: Gluttonous for springtails and insects, in captivity they accept fine crushed dry granules and freeze-dried food (Daphnia, Tubifex). Quality feed and liquid vitamins enhance facial red pigmentation.
Water Quality: The absolute biological indicator: the red snout fades at the first sign of nitrites or ammonia spikes. The water must be mature (cycled for months) and preferably softened with oak extracts.
Compatibility and Cohabitation: The "Dither fish" par excellence. It is paired with large peaceful cichlids (Apistogramma, Geophagus, Satanoperca, Angelfish) since their quiet but tireless swimming signals to the cichlid that "there are no predators lurking" in the tank.
Aquarium Breeding: Scatterer of photosensitive eggs. They require a very mature sponge filter (newborns eat infusoria), and a total absence of light. Upon hatching, larvae cannot withstand strong lighting for the first 2 weeks.
Risks and Diseases: Decimation from water stress. Water changes made with significant thermal shock (even just 2-3°C / 4-5°F) cause swimming paralysis or terrifying Ich infestations.

Geographic Origin and Distribution

Lower Amazon River Basin in Brazil. Compared to the Bleheri ("false" Rummy), the Rhodostomus inhabits areas further downstream, in clear but peaty rivers (Clear/Black water mix).

Origin

Amazon, Orinoco, and Guianas

Fish profile

Temperament
Active
They are exceptionally peaceful and somewhat shy, requiring a large school of at least six individuals to feel secure. When kept in smaller numbers, they may become stressed, lose their vibrant colors, and hide continuously. A proper schooling environment encourages their natural, confident behaviors and tight grouping dynamics.
Diet
Omnivore
In the wild, they are micro-predators feeding on small insects, worms, and crustaceans. In the aquarium, they readily accept high-quality crushed flakes, micro-pellets, and freeze-dried foods. Supplementing their diet with live or frozen foods like daphnia, baby brine shrimp, and bloodworms will enhance their coloration and vitality.
Sex ratio
School
Keeping a balanced ratio or a slight majority of females is generally recommended to prevent males from constantly harassing a single female. In a large enough school, the sex ratio becomes less critical as aggression is dispersed. A larger group naturally forms a healthy hierarchy, minimizing any stress related to breeding behavior.
Feeding frequency
Twice daily
It is highly recommended to feed them two to three small meals a day rather than one large one. Offering only what they can consume within a couple of minutes ensures minimal food waste and prevents water quality degradation. Frequent, small feedings closely mimic their natural foraging behavior in the wild.
Bioload
Low to Medium
These small tetras produce a minimal bioload, making them excellent candidates for smaller or heavily planted aquariums. They do not generate significant amounts of waste compared to larger species, reducing the burden on the filtration system. However, keeping them in large schools will naturally increase the overall waste output, requiring adequate biological filtration.
Flow
Strong
They prefer a moderate to low water flow that simulates the slow-moving tributaries and flooded forest regions of their natural habitat. Strong currents can exhaust these small fish and cause them significant stress over time. Providing areas of still water, particularly near dense vegetation, allows them places to rest comfortably.
Jump risk
No
Reproduction
Egg scatterer
Breeding these tetras can be challenging as they are egg-scatterers that provide no parental care. They require soft, acidic water and dim lighting to trigger spawning behavior successfully. A separate breeding tank with fine-leaved plants or a spawning mop is necessary, and parents must be removed immediately after laying eggs to prevent predation.
Compatibility & tankmates
Peaceful
This species is incredibly peaceful and thrives in a community setup with other similarly sized, non-aggressive fish. Excellent tank mates include small rasboras, Corydoras catfish, and peaceful dwarf cichlids. They should never be kept with large or aggressive species that might view them as prey or cause them undue stress.
Tank level
Middle
These fish primarily occupy the middle to upper levels of the water column in the aquarium. They are active swimmers that appreciate ample open swimming space combined with areas of dense planting. While they occasionally dart to the surface for food or explore the bottom, they will spend most of their time cruising the midwater.

Window to the official scientific data of the species

Data synced on: 06/15/2026

Scientific Parameters & Models

Trophic level
3.1 ± 0.4 se
Resilience
High (less than 15 months)
Phylogenetic uniqueness (PD50)
0.625
Bayesian Length-Weight
a = 0.00389, b = 3.12
VulnerabilityLow vulnerability (10 / 100)

Image gallery

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

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Last updated: 06/30/2026
True Rummy-Nose Tetra (Hemigrammus rhodostomus) Care Guide & Tank Setup | Atlarium