FishFreshwaterIntermediate
©AI Generated·Proprietary
Barred hemiodus
Hemiodus quadrimaculatus
A medium-large silver characin with flanks crossed by dark vertical bars, with fast, powerful swimming reminiscent of a silver torpedo. Native to the Negro, Trombetas and Araguari basins in South America, it is a river fish that requires large, long tanks with ample open swimming space and good oxygenation. Gregarious and schooling: must be kept in groups. Its intense activity and speed can intimidate small, timid fish. Powerful jumper: lid essential. Requires vegetable component in diet.
Water Temperature
23 - 27 °C
pH Value
6 - 7.5
Water type
Freshwater
Tank level
Middle
Adult size
14 cm
Minimum tank volume
>= 280 L
Minimum group
>= 6
GH
2 - 12 dGH
KH
1 - 6 dKH
TDS
40 - 240 ppm
Conductivity
63 - 375 uS/cm
Species description
Geographical Origin and Habitat: Rio Negro and Orinoco basin. Relentless swimmer of the huge open waters of fast-flowing South American river systems, almost never on closed bottoms.
Taxonomy and Morphology: Four-Spotted Hemiodus (Hemiodus quadrimaculatus). Very tapered and hydrodynamic, the "torpedo-suppository" shape betrays a fish made to cut through water. It has the typical "Hemiodus" jaw adapted both for hunting and scraping.
Social Behavior: A rocket in captivity. Perennial swimmer in a loose school; does not tolerate small aquariums. Must be in a group of 6+ to dissipate chronic nervousness: solitary it injures itself by throwing itself against the glass in a panic.
Coloration and Sexual Dimorphism: Gorgeous mirrored silver base framed by a large black spot in the middle of the body and other faded spots. The centerpiece is the tail: the lower lobe is half crossed by a very black oblique ribbon. No visible dimorphism.
Care, breeding and tankmates
Aquarium Setup: Requires the "Track": a tank with at least 150 cm (60 inches) of empty front! Discard intricate furnishings that obstruct their swimming. MANDATORY and weighted LID: their jumps in the water pierce even soft plastic nets.
Diet and Feeding: Micro-predators / Omnivores. They feed in mid-column or on the surface in a frantic manner. They like scattered brine shrimp and bloodworms, mixed with vegetable flakes for their herbivorous streak (they often pick at young vallisneria shoots).
Water Quality: Extremely sensitive (like almost all Hemiodontidae) to pollutants such as nitrites and pH fluctuations; they need titanic filters with high hourly flow rates to simulate the original currents.
Compatibility and Cohabitation: Fabulous with Large slow South American Cichlids (Geophagus, Uaru, Severum) and colossal Plecostomus. Their size saves them from large predators, and their mouth is not a danger to any other fish (no Corydoras or Neons).
Aquarium Breeding: Practically never successfully reported in the domestic environment, due to the need for immense river spaces, strong monsoon rain triggers and advanced age for sexual maturity.
Risks and Diseases: The panic cranial wound (Head-Smash). Just turning on the light suddenly (without a dimmer) is enough for the terrified school to throw itself at tens of km/h against the glass, dying instantly from brain trauma.
Geographic Origin and Distribution
Rio Negro and Orinoco basin. Relentless swimmer of the huge open waters of fast-flowing South American river systems, almost never on closed bottoms.
Origin
Amazon, Orinoco, and Guianas
Fish profile
- Temperament
- Peaceful
- They are peaceful but highly skittish fish that can startle easily if their environment is suddenly disturbed. They must be kept in groups; solitary individuals will become intensely stressed and prone to disease. Their restless nature requires a calm environment to prevent them from constantly darting into the tank glass.
- Diet
- Omnivore
- They are opportunistic omnivores that consume a variety of small invertebrates, plant matter, and algae in the wild. In captivity, they will readily accept high-quality flakes, pellets, and freeze-dried items. It is beneficial to offer them a varied diet that includes live or frozen foods and some spirulina or vegetable-based flakes.
- Life expectancy
- 5-8 years
- In a large and well-managed home aquarium, Hemiodus quadrimaculatus can live on average between 5 and 8 years. Its longevity strictly depends on the provision of a very spacious tank that allows for the frantic swimming of this active fish, reducing confinement stress. Impeccable water conditions, high oxygenation, and a varied diet are essential for preventing health problems and supporting their fast metabolism.
- Adult size
- 14 cm
- The catalog's scalar value is 14 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 13.1 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Hemiodus quadrimaculatus (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
- School
- There are no obvious external differences between males and females, making sexing nearly impossible. Keeping them in a group of at least six individuals ensures a natural balance and reduces any potential stress. A large group also encourages their natural schooling dynamics, which is spectacular to watch.
- Feeding frequency
- Twice daily
- Feeding them twice a day is recommended to fuel their high-energy lifestyle. They are ravenous eaters that will quickly snatch food from the water column before it reaches the bottom. Care should be taken to ensure that more timid tank mates also receive adequate nutrition during feeding times.
- Bioload
- Medium to High
- They have a moderate bioload due to their highly active nature and substantial appetite. Because they are fast swimmers and grow to a respectable size, they require excellent filtration to manage their metabolic waste. Regular water changes are critical to keeping nitrate levels low, which they are particularly sensitive to.
- Flow
- Strong
- These fish originate from fast-flowing rivers and streams and therefore thrive in aquariums with strong water movement. High flow rates encourage their natural schooling behavior and provide the exercise they need to stay healthy. Additional powerheads or wavemakers are highly recommended to replicate their natural environment.
- Jump risk
- Yes
- They are notorious jumpers and are incredibly fast, making them highly susceptible to launching themselves out of the tank. A tightly fitting, heavy cover glass or lid is absolutely essential when keeping this species. Even small gaps around filters or heaters should be carefully covered to prevent accidents.
- Reproduction
- Oviparous
- Breeding Hemiodus species in the home aquarium is extremely rare and has seldom been documented. In the wild, they are believed to be pelagic spawners that scatter large numbers of eggs in open water. Commercial breeding generally relies on hormone injections in large outdoor aquaculture ponds.
- Compatibility & tankmates
- Community
- They are peaceful, active schooling fish that do well with other medium-sized, robust species. Good tank mates include larger tetras, peaceful cichlids, and various bottom-dwelling catfish. They can occasionally outcompete slower or more timid fish for food due to their incredible swimming speed.
- Tank level
- Middle
- They are energetic midwater to upper-level swimmers that require an elongated tank with vast amounts of open swimming space. They will constantly cruise back and forth across the length of the aquarium. Decor should be kept mainly to the perimeter to avoid obstructing their swimming paths.
Scientific Parameters & Models
FishBase
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 2.6 ± 0.27 se
- Phylogenetic uniqueness (PD50)
- 0.5
- Bayesian Length-Weight
- a = 0.01096, b = 3.09
- 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.
