Rainbow Shark
Epalzeorhynchos frenatum
The Rainbow Shark (Epalzeorhynchos frenatum) is the close cousin of the Red Tail Shark. Compared to the Bicolor (which has only a red tail), the Frenatus has a more elongated, dark green-grey body, with ALL fins colored bright orange-red. It also exists in a highly popular albino variant with a pinkish-white body. Although it shares the shark-like morphology, it has a slightly less antisocial temperament than its cousin, but remains a strongly territorial bottom algae-scraper, capable of terrorizing improperly prepared or populated aquariums.
Température de l’eau
22 - 28 °C
Valeur du pH
6.5 - 7.5
Type d'eau
Eau douce
Niveau dans le bac
Fond
Taille adulte
15 cm
Volume minimal du bac
>= 150 L
Groupe minimal
>= 1
GH
5 - 15 dGH
KH
2 - 7 dKH
TDS
95 - 295 ppm
Conductivité
148 - 461 uS/cm
Description de l'espèce
Geographical Origin and Habitat: Native to the Chao Phraya, Mekong, and Xe Bang Fai river basins in Southeast Asia (Thailand, Laos, Cambodia). Inhabits streams with sandy or rocky bottoms, migrating seasonally to flooded forests and floodplains during the rainy season to spawn.
Taxonomy and Morphology: Member of the Cyprinidae family. The body is torpedo-shaped, streamlined and elegant, more elongated than its congener E. bicolor. The mouth is inferior, surrounded by sensory barbels for tactile exploration of the substrate. Measures up to 15 cm (6 inches) in captivity.
Social Behavior: Quarrelsome, territorial, but less lethal than the Red Tail Shark. While dynamic schooling fish are tolerated, intolerance toward its own kind is absolute: in nature, they do not tolerate each other outside the breeding season. It spends its time aggressively patrolling the perimeter of its assigned territory on the bottom.
Coloration and Sexual Dimorphism: The body ranges from dark olive green to charcoal gray, sometimes crossed by a faint longitudinal stripe. All fins (not just the tail) are a bright orange/red leaning towards coral. Mature males are distinctly more slender, with more pointed fins and dark margins on the anal fin.
Soins, reproduction et cohabitation
Aquarium Setup: Tank at least 120 cm (4 feet) long. The bottom must be strictly sandy (not sharp gravel which would erode its mouth). The insertion of dozens of visual obstacles (large Manila roots, smooth rocks, and patches of Cryptocoryne) is essential to delimit territories and break its line of sight, calming its aggressiveness.
Diet and Feeding: Benthic grazer and omnivore. Excellent devourer of green hair algae and aufwuchs when young. In adulthood, it requires high-end sinking vegetable flakes, Spirulina-based pellets, but also bi-weekly protein supplements (Daphnia, Brine shrimp) to support its rapid metabolism.
Water Quality: Demands stable and crystal-clear waters. Temperature: 22.0-28.0 °C (72-82 °F). pH: 6.5-7.5. GH: 5.0-15.0. A strong current (via wavemakers or oversized filters) and high oxygen saturation faithfully replicate its native river ecosystem and keep it healthy.
Compatibility and Cohabitation: Never insert more than one individual per aquarium, nor pair it with the Red Tail Shark. Can coexist with large Barbs (Tiger, Denisonii), large Danios, or robust Loaches. Avoid small, slow fish, or those with long fins (Guppies, Bettas), which would be stressed and nipped relentlessly.
Aquarium Breeding: Documented very few times in the amateur field in enormous tanks (over 1000 liters / 250 gallons). Commercialization depends 100% on hormonally induced reproduction in Asian commercial farms. They scatter eggs in the current and show no parental care.
Risks and Diseases: Frequent victim of malnutrition in newly set up sterile aquariums (lack of biofilm). Extremely sensitive to ammonia concentration. Over 50% of home deaths are caused by escaping via leaps out of the tank: a tight-fitting lid is not optional.
Origine et répartition géographiques
Native to the Chao Phraya, Mekong, and Xe Bang Fai river basins in Southeast Asia (Thailand, Laos, Cambodia). Inhabits streams with sandy or rocky bottoms, migrating seasonally to flooded forests and floodplains during the rainy season to spawn.
Origine
Sélection et cultivarsAsie du Sud et du Sud-Est
Profil de poisson
- Tempérament
- Aggressive
- They are highly territorial and can be aggressive, particularly towards fish with similar shapes or colors. While peaceful with top-dwelling species, they relentlessly chase other bottom-dwellers. Providing a large footprint and broken lines of sight helps diffuse their aggression.
- Régime alimentaire
- Omnivore
- This species is primarily an omnivorous scavenger that constantly feeds on algae and biofilm. In captivity, they readily accept sinking pellets, algae wafers, and fresh blanched vegetables. Occasional meaty protein treats like bloodworms or brine shrimp are highly beneficial.
- Espérance de vie
- 6-10 years
- Taille adulte
- 15 cm
- Ratio des sexes
- Group
- Because of their severe territorial aggression, they should be kept strictly singly. Keeping multiple individuals usually results in fatal fights and chronic stress. Therefore, maintaining a specific sex ratio is generally irrelevant for home aquariums.
- Fréquence d'alimentation
- Twice daily
- Feed them once or twice a day in small, manageable portions. Offer only what they can entirely consume within a few minutes. Overfeeding can lead to poor water quality and severe health issues over time.
- Charge biologique
- Medium
- The Rainbow shark produces a moderate amount of waste in the aquarium. Maintaining a robust and efficient filtration system is essential for their health. Regular weekly water changes are highly recommended to prevent harmful nitrate accumulation.
- Courant
- Strong
- They prefer moderate to strong water flow that simulates their natural riverine habitats. Good oxygenation and steady water movement encourage their natural active swimming behavior. Adding a dedicated powerhead can help replicate these ideal conditions.
- Risque de saut
- Yes
- Rainbow sharks are notorious jumpers, especially when first introduced to a new environment. A tight-fitting, secure lid with no gaps is absolutely mandatory. Any open spaces around filters or heaters should be carefully covered.
- Reproduction
- Oviparous
- Breeding them in home aquariums is extremely difficult and rarely achieved successfully. Commercial breeding relies heavily on hormone injections in large outdoor ponds. They are egg-layers but exhibit intense aggression during the spawning process.
- Compatibilité et compagnons
- Peaceful
- They are semi-aggressive and highly territorial towards other bottom-dwelling fish. It is best to keep only a single individual per aquarium to avoid fighting. They can co-exist well with fast-moving, upper-level schooling fish like barbs or tetras.
- Niveau dans le bac
- Bottom
- They are predominantly bottom dwellers that spend most of their time grazing on surfaces. However, they will also actively patrol the lower and middle levels of the tank. Providing plenty of caves, driftwood, and hiding spots is essential.
Modèles et paramètres scientifiques
FishBase
Fenêtre sur les données scientifiques officielles de l’espèce
FishBase v25.04Données synchronisées le : 15/06/2026
- Niveau trophique
- 2,3 ± 0,18 se
- Résilience
- Élevée (moins de 15 mois)
- Singularité phylogénétique (PD50)
- 0.5625
- Relation bayésienne longueur-poids
- a = 0.00794, b = 3.02
- VulnérabilitéVulnérabilité faible (10 / 100)
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