Bass Tetra
Hemigrammus marginatus
A larger tetra than its congeners, with characteristic and flashy golden margins ('marginatus') outlined in clear black on the odd fins, particularly on the majestic forked tail.
Température de l’eau
22 - 28 °C
Valeur du pH
6 - 7.5
Type d'eau
Eau douce
Niveau dans le bac
Milieu
Taille adulte
5 cm
Volume minimal du bac
>= 100 L
Groupe minimal
10
GH
2 - 12 dGH
KH
2 - 10 dKH
TDS
50 - 280 ppm
Conductivité
78 - 438 uS/cm
Description de l'espèce
Geographical Origin and Habitat: Very widespread species: from the Orinoco basin to the Amazon down to the Paraná and Paraguay basins in Argentina. Inhabits countless habitats but prefers clear forest streams and slow-flowing rivers with abundant vegetation.
Taxonomy and Morphology: Bass Tetra / Marginated Tetra (Hemigrammus marginatus). The name "marginatus" refers to the distinctive chromatic margins of its fins. Features the silvery-green body characteristic of the group.
Social Behavior: Schooling characin, peaceful but very dynamic. Interacts elaborately within the school, with continuous displays among males that never result in physical harm. Must be strictly kept in schools of at least 10 specimens.
Coloration and Sexual Dimorphism: Sparkling silvery and greenish livery. Distinguished by a broad green-gold horizontal stripe and a beautiful caudal fin: central black spot bordered above and below by bright yellow/white spots. Females have a more curved belly.
Soins, reproduction et cohabitation
Aquarium Setup: Tank of at least 80 cm (32 inches), densely planted on the sides and bottom (Echinodorus, Vallisneria), leaving the central swimming space open. A dark bottom will enormously highlight the color contrast of the fins.
Diet and Feeding: Undemanding. Avidly accepts flakes, micro-pellets, but to maintain high immune levels it is good to administer daphnia, cyclops, artemia (live or frozen) at least twice a week.
Water Quality: Very robust fish thanks to its wide geographic distribution. Tolerates a wide range of hardness and temperatures (22-28°C / 72-82°F), but hates ammonia accumulations or immature filters. Appreciates a moderate current.
Compatibility and Cohabitation: Exceptional tankmate for almost all South American community tanks of appropriate size. Perfect with Corydoras, Ancistrus, and dwarf Cichlids (Apistogramma). Not to be mixed with medium-large Cichlids that will prey on it.
Aquarium Breeding: Easy to achieve in dedicated tanks with soft and weakly acidic water. They lay dozens of eggs scattering them in mosses or on synthetic mops. Breeders must be removed quickly to save the offspring.
Risks and Diseases: Rarely subject to diseases if kept under stable conditions. Introduction into tanks with immature filters or ammonia spikes causes rapid fin deterioration (Fin rot) and asphyxiation.
Origine et répartition géographiques
Very widespread species: from the Orinoco basin to the Amazon down to the Paraná and Paraguay basins in Argentina. Inhabits countless habitats but prefers clear forest streams and slow-flowing rivers with abundant vegetation.
Origine
Océans tropicaux et récifsAmazonie, Orénoque et GuyanesAmérique du Nord
Profil de poisson
- Tempérament
- Semi-aggressive
- 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.
- Régime alimentaire
- 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.
- Espérance de vie
- 4-5 years
- Taille adulte
- 5 cm
- Ratio des sexes
- 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.
- Fréquence d'alimentation
- 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.
- Charge biologique
- Low
- 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.
- Courant
- Stagnant
- 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.
- Risque de saut
- Yes
- Like many tetras, they are capable of jumping, particularly when startled by sudden movements or lighting changes. A secure, well-fitting aquarium lid is strongly recommended to prevent any accidental escapes. Floating plants can also help make them feel more secure and reduce their instinct to jump.
- Reproduction
- Oviparous
- 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.
- Compatibilité et compagnons
- Semi-aggressive
- 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.
- Niveau dans le bac
- 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.
Modèles et paramètres scientifiques
FishBase
Fenêtre sur les données scientifiques officielles de l’espèce
FishBase v25.04Données synchronisées le : 15/06/2026
- Niveau trophique
- 2,8 ± 0,28 se
- Résilience
- Élevée (moins de 15 mois)
- Singularité phylogénétique (PD50)
- 0.5
- Relation bayésienne longueur-poids
- a = 0.01585, b = 2.98
- VulnérabilitéVulnérabilité faible (10 / 100)
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