True Rummy-Nose Tetra
Petitella rhodostoma
The Petitella rhodostoma 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.
Temperatura da água
24 - 28 °C
Valor de pH
5.5 - 7
Tipo de água
Água doce
Nível do tanque
Meio
Tamanho adulto
5 cm
Volume mínimo do tanque
>= 120 L
Grupo mínimo
>= 10
GH
1 - 10 dGH
KH
1 - 5 dKH
TDS
25 - 200 ppm
Condutividade
39 - 313 uS/cm
Descrição da espécie
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 (Petitella rhodostoma). 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.
Cuidado, criação e companheiros de tanque
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.
Origem e distribuição geográfica
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).
Origem
Amazônia, Orinoco e Guianas
Perfil de peixe
- Temperamento
- 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.
- Dieta
- 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.
- Expectativa de vida
- 5-8 years
- Tamanho adulto
- 5 cm
- Proporção sexual
- 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.
- Frequência de alimentação
- 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.
- Carga biológica
- 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.
- Fluxo
- 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.
- Risco de salto
- No
- Reprodução
- 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.
- Compatibilidade e companheiros de tanque
- 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.
- Nível do tanque
- 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.
Modelos e parâmetros científicos
FishBase
Acesso aos dados científicos oficiais da espécie
FishBase v25.04Dados sincronizados em: 15/06/2026
- Nível trófico
- 3,1 ± 0,4 se
- Resiliência
- Alta (menos de 15 meses)
- Unicidade filogenética (PD50)
- 0.625
- Relação bayesiana comprimento-peso
- a = 0.00389, b = 3.12
- VulnerabilidadeVulnerabilidade baixa (10 / 100)
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