Heros efasciatus

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Heros efasciatus, also known as Green Severum, is a large South American cichlid valued for its elegant shape and olive-green coloration. Native to the Amazon basin, it inhabits quiet waters where submerged wood, leaf litter, and cover shape its surroundings. In an aquarium, it becomes a substantial fish, usually peaceful outside breeding periods but capable of defending a territory. Successful care requires a spacious aquarium, warm and stable water, and a varied diet with plenty of plant matter. This species is popular and very common in the aquarium trade, although color and body shape can vary between strains and local forms.

General species description

Heros efasciatus is a medium-to-large cichlid with a deep, laterally compressed body. It belongs to the family Cichlidae and shows the typical severum profile: well-developed fins, a sturdy head, and an alert response to its surroundings. Adults mainly use quiet, structured areas around roots, branches, and vegetation. Their temperament is generally moderate when they have enough room, but they become territorial as a pair, especially during spawning. They can be kept in a large South American community aquarium with similarly sized tank mates. The green form remains very common in the hobby, although coloration and body proportions may differ according to the strain.

Geographic origin and biotope

Reference country: Brazil, with the species associated with the Amazon basin and particularly the Rio Negro region. Heros efasciatus uses slow-moving streams, side channels, forest lagoons, and seasonally flooded areas. The habitat is often characterized by warm, soft water with low mineral content and varying levels of tannins. Banks are bordered by forest, roots, fallen branches, and accumulated leaves. Aquatic plants may be abundant in quiet sections, but woody cover and leaf litter are generally more important than dense submerged vegetation. In an aquarium, a layout of wood, smooth rocks, and shelters reflects its natural habitat better than a heavily planted tank without structure.

Precise location and local name

The historical locality generally associated with the species is the Rio Negro in Brazil, within the Amazon drainage. In its native region, cichlids of this type may be referred to by vernacular names related to acarás, while the international trade mainly uses Severum or Green Severum. In Brazilian Portuguese, “acará-severo” is commonly associated with severums. Trade names can sometimes include several closely related forms or species, which explains differences in adult coloration. For reliable identification, the scientific name, collection locality, and mature appearance should be considered together rather than relying only on the sales name.

Appearance and physical characteristics

Heros efasciatus has a deep, oval, strongly compressed body, with long dorsal and anal fins. Its base color is usually olive green to greenish brown, with blue or golden reflections that change with mood, age, and strain. Faint vertical bars may appear, especially in juveniles or stressed fish. The fins can develop reddish, orange, or amber tones, particularly in adults ready to breed. Its mouth is suited to grazing and taking small prey. Adult fish commonly reach about 20 cm in a well-maintained aquarium, with a substantial body mass that calls for a long tank and strong biological filtration.

General diet

Heros efasciatus is an omnivore with a strong herbivorous tendency. In the wild, it consumes algae, plant fragments, organic debris, small invertebrates, and food gathered from surfaces or substrate. In aquaria, the staple diet should be a quality complete food, supplemented with plant-based pellets, edible wafers or leaves, and frozen foods such as brine shrimp, finely chopped krill, or mosquito larvae. Blanched vegetables, including zucchini, spinach, or cucumber, can add variety. A diet excessively rich in animal protein can encourage obesity; provide a substantial plant component and offer small portions regularly instead.

Essential data

• Name of original river: Rio Negro
• Local name used: Acará-severo
• Origin of the scientific name: Name assigned when the species was formally described
• Full-name etymology: Heros means “hero” in Greek; efasciatus combines e-, “without,” and fasciatus, “banded”
• Common/vernacular names: Green Severum, Green Severum cichlid, Severum
• Family: Cichlidae
• Subfamily: Cichlinae
• Name pronunciation: hee-ross eh-fa-see-ah-tuss
• Discovery: Johann Jakob Heckel, 1840
• Maximum adult size: About 20 cm
• Water temperature and pH: 24 to 29 °C; pH 6.0 to 7.5
• Watercourse appearance and surrounding vegetation: Quiet water, submerged wood, leaf litter, forested banks, and variable vegetation
• Typical tank mates: Geophagus altifrons, Pterophyllum scalare, Symphysodon aequifasciatus, Hoplarchus psittacus, Satanoperca jurupari, Hypostomus plecostomus
• Temperament and behavior: Usually calm, territorial, and more aggressive while breeding
• Water depth: Quiet shallow to medium-depth areas near cover
• Sexual dimorphism: Difficult to determine reliably; mature males may develop more pronounced markings and fins
• Bottom structure and flow: Sandy or muddy bottom, woody debris, and low to moderate current

In your aquarium

To keep Heros efasciatus successfully, provide a spacious aquarium, effective filtration, and regular water changes. A layout made of roots, rounded rocks, and open swimming areas allows each fish to find shelter. Keep the temperature stable at 24 to 29 °C, with soft to slightly acidic water and good oxygenation. Avoid very small fish that may be intimidated or swallowed, as well as overcrowding. A diet containing plenty of plant matter, combined with adequate space, helps maintain body condition and coloration. During breeding, watch for pair territory defense and rearrange the décor if necessary.