Severum (Heros severus)

What is a Severum cichlid?

The severum (Heros severus) is a large, disc-shaped cichlid from South America — specifically the Amazon and Orinoco river basins spanning Venezuela, Brazil, and Colombia. It reaches up to 25 cm (10 in) and carries a stocky, oval body profile that has earned it the informal nickname “poor man’s discus.” The wild form is olive-green to brownish with seven or eight dark vertical bars and a subtle iridescent sheen across the flanks. Captive colour morphs are widely available: the all-yellow gold severum and the orange-bellied rotkeil (red-shoulder) form are both common in the hobby, and many stores stock these colour variants more readily than the natural wild-type.

What sets the severum apart in the cichlid world is its temperament. Despite growing to a size that commands attention, it is considerably more composed than most large cichlids — capable of sharing a tank with robust, similarly-sized companions without the relentless aggression that makes many large cichlids difficult to house in anything but a species setup. It can live 8–12 years in good conditions, making it a long-term commitment and a rewarding centrepiece fish.

Where do severums come from in the wild?

Wild severums inhabit the blackwater and clearwater rivers of the Amazon and Orinoco basins, ranging across Venezuela, Brazil, and Colombia. These rivers are typically warm, heavily tannin-stained, soft, and acidic — the opposite of hard, mineral-rich tap water. In nature, severums occupy the middle column of the water, browsing on plant matter, fallen fruit, algae, and invertebrates along the river margins. Submerged wood, root tangles, and dense riparian vegetation are the standard habitat.

This origin explains the species’ water-chemistry preferences. Wild-caught fish demand soft, acidic conditions; captive-bred individuals are more adaptable and tolerate a broader pH range, but staying within the preferred parameters — pH 5.5–7.5, hardness 2–12 dGH — keeps the fish at its best. Blackwater tannins from driftwood or Indian almond leaves are welcomed by this species, even in a captive setting.

What tank size and setup does a severum need?

A single adult severum needs at least 280 litres (74 gallons) with a long tank footprint — the floor space matters more than height for a fish that swims the middle column. A bonded pair or a group alongside tank-mates will need 380–450 L (100–120 gal) or more to distribute territory sensibly. Do not underestimate the eventual size: juveniles sold at 5–7 cm (2–3 in) reach full size within 18–24 months under good conditions.

Decorate with large pieces of driftwood, smooth rounded rocks, and robust plants. Severums browse and occasionally uproot vegetation, so choose hardy, anchored species: Amazon sword (Echinodorus spp.) planted in substrate pots, anubias and java fern tied to hardscape, and hornwort or vallisneria for background cover. Avoid delicate stem plants — they will not survive long. Maintain a clear open swimming corridor through the centre of the tank. Filtration should be powerful; a fish approaching 25 cm (10 in) generates considerable waste, so target a turnover rate of 8–10× the tank volume per hour and supplement with frequent partial water changes.

What water parameters does a severum need?

• Temperature: 23–30 °C (73–86 °F). The middle of that range (25–27 °C / 77–81 °F) suits everyday maintenance; the upper end is useful when conditioning a pair for breeding.
• pH: 5.5–7.5. Captive-bred fish adapt to slightly higher values, but avoid consistent readings above 7.5.
• Hardness: 2–12 dGH. Soft to moderately hard water is ideal; very hard water increases stress over time.

Stability is the priority. Large water changes with well-matched temperature and pH are far less disruptive than small, infrequent changes that allow parameters to drift. Aim for 25–30% weekly water changes and test regularly, especially in tanks approaching maximum bioload.

What do severums eat?

Severums are omnivores with a notable plant-browsing tendency. In the aquarium, a varied diet produces the best health and colour. A quality large-pellet cichlid food as the staple can be supplemented with:

• Vegetable matter: blanched zucchini, spinach, peas, spirulina flakes, or algae wafers
• Protein items: frozen or live bloodworms, earthworms, prawns, and occasional whole crickets or other insects
• Frozen foods: krill and Mysis shrimp for variety and conditioning

Feed once or twice daily, offering only what the fish will consume in two to three minutes. Severums are enthusiastic eaters and will overeat if given the opportunity, leading to obesity and water quality problems. Vary protein and plant matter across the week rather than relying on a single staple.

Are severums aggressive — and what fish can live with them?

Severums are classified as semi-aggressive, but the label requires context. Day-to-day behaviour is generally calm and curious; they often recognise their keeper and can become quite interactive. The aggression surfaces in specific situations: defending a territory against intruders of similar size, and especially during courtship and spawning, when even a previously tolerant individual will drive other fish from a large area around the nest site.

The practical rule is to choose robust tank-mates of comparable size that can hold their own without being aggressive enough to harass the severum. Good pairings include larger peaceful South Americans such as geophagus, festivum, and large-growing tetras (bleeding heart, silver dollars), as well as armoured catfish like common plecos or large-bodied synodontis. Avoid small fish (anything under 8 cm / 3 in is at risk of being swallowed), very slow or timid species, and fish with long trailing fins that may be nipped.

For a full, filterable list of compatible and incompatible species — including scoring by size, temperament, and water overlap — see Severum tank mates.

How do you tell male and female severums apart?

Sexing severums accurately requires patience, as juveniles are virtually identical. Adult males develop the clearest distinguishing feature: worm-like facial markings — a network of squiggly iridescent lines across the cheeks and gill covers — which become more pronounced as the fish matures. Females generally remain plainer-faced with much less facial patterning, or none at all. Breeding males may also develop a modest nuchal hump (a slight forehead thickening), though this is less exaggerated than in many other cichlid species. Body size alone is not a reliable indicator in young fish; wait until individuals are at least 12–15 cm (5–6 in) before drawing conclusions.

How do severums breed?

Severums are open substrate spawners. A compatible pair will select a flat, cleaned surface — a broad flat rock, a smooth section of driftwood, or even the aquarium glass — and spawn up to several hundred eggs directly on it. Both parents are typically engaged in guarding the spawn, fanning the eggs, and later shepherding the free-swimming fry.

Conditioning a pair involves raising temperature toward the upper range (28–30 °C / 82–86 °F), increasing protein in the diet, and performing larger water changes to simulate the onset of the wet season. If the tank contains other fish, expect the parents to become significantly more aggressive during the spawning period; a dedicated breeding tank of at least 200 L (53 gal) avoids conflict. Fry are small and will initially accept newly hatched brine shrimp and micro-pellet foods. The parents often remain attentive to the fry for several weeks. Breeding difficulty is rated medium — the fish do most of the work once a compatible pair is established, but obtaining a proven pair takes time.

What diseases do severums commonly get?

The most common health issues in severums mirror those of South American cichlids generally:

• Hole-in-the-head (HITH): Pitting or lesions around the lateral line and head, linked to water quality decline, activated carbon overuse, and nutritional deficiency — especially vitamin C and varied diet.
• Ich (white spot): White pinpoint spots across the body and fins, triggered by temperature fluctuations or the stress of transport.
• Intestinal parasites: Wild-caught fish are more prone; symptoms include whitish stringy faeces and wasting despite normal appetite.
• Bacterial infections and fin erosion: Usually secondary to wounds from tank-mate conflict or poor water quality.

Prevention centres on the same fundamentals that govern all cichlid care: excellent filtration, consistent water parameters, a varied and nutritious diet, and a quarantine tank for all new arrivals before introduction to the display.

Health note: medication dosing and disease diagnosis are beyond the scope of a care profile. For a sick severum, confirm symptoms against a reputable veterinary or fish-health source before medicating. Many conditions attributed to disease are resolved by water-quality correction alone.

How long does a severum live?

A well-maintained severum lives 8–12 years in the aquarium — sometimes longer in exceptional conditions. That longevity is one reason they are considered a serious keeper’s fish: you are committing to a decade or more of care. Provide stable, clean water within the preferred parameters, a varied diet, a suitably large tank, and compatible companions, and a severum will reward that investment with years of active, personable behaviour and impressive colour.