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Aimara (Giant Wolf Fish)
Hoplias aimara
The Fearless Amazonian Assassin (100-120 cm / 40-47 inches). The Hoplias aimara is not a community fish; it is a solitary, hyper-aggressive, armored dinosaur. It is the absolute apex predator of its genus, heavily built like a torpedo and armed with terrifying, thick canine teeth that proudly protrude even when its mouth is fully closed. Unlike skittish predators that hide, the Aimara is infamously fearless: it will actively attack and charge anything that enters its territory, including massive tankmates and the owner's bare hands. It demands massive, heavily armored 'solitary confinement' tanks and poses a genuine physical bite risk to careless owners.
- Taxonomy
- Class:ActinopteriOrder:CharaciformesFamily:ErythrinidaeGenus:HopliasSpecies:Hoplias aimara
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Water Temperature
24 - 30 °C
pH Value
6 - 7.5
Water type
Freshwater
Tank level
Bottom and middle
Adult size
100 cm
Minimum tank volume
>= 500 L
Minimum group
>= 1
GH
4 - 15 dGH
KH
2 - 7 dKH
TDS
80 - 295 ppm
Conductivity
125 - 461 uS/cm
Species description
Geographical Origin and Habitat: Amazon River basin (Brazil, Guyana, Venezuela). Inhabits deep river beds, where it waits for prey, but does not disdain strong oxygen-rich rapids.
Taxonomy and Morphology: Aimara Wolf Fish (Hoplias aimara). The apex of wolf fish. Monstrous (reaches one meter / 3.3 feet and 40kg / 88 lbs). It has an armored head, huge projecting canines visible from jaws designed to shear and an immense tail for lightning accelerations.
Social Behavior: The asocial and hyper-aggressive killer. It is an ambush predator that lives strictly isolated (Strictly Solitary). It will attack anything that moves, often breaking tanks and hurling its snout against fingers on the glass.
Coloration and Sexual Dimorphism: Pure camouflage for the Amazonian seabed: a mix of mud brown, black and olive-silver, with a typical opaque black "mark" in the shape of an inverted V (or bar) behind the brachial operculum. No dimorphism.
Care, breeding and tankmates
Aquarium Setup: Tank for MONSTERS. An indoor pool of at least 250 cm (100 inches) (3000 liters / 800 gallons) equipped with CEMENTED LIDS. It will smash thin glass and jump out easily breaking plastic lids if frightened. Irremovable massive woods.
Diet and Feeding: Extreme carnivore (Piscivore). Can shear large fish in half. Must be fed (using LONG TONGS) with salmon steaks, whole trout, mussels and prawns. DO NOT put hands in the tank during meals or you risk stitches at the ER.
Water Quality: Requires strong currents to reproduce the rapids it comes from (essential for oxygenation) and industrial filters to support the colossal meals. Resists pH variations but cannot stand prolonged cold.
Compatibility and Cohabitation: None. It will kill and eat (or dismember) any tankmate sooner or later, including sharks, pacus and arowanas. Keep it STRICTLY as the only animal in the tank (Species-only).
Aquarium Breeding: Impossible in home aquariums. Forming a pair invariably leads to the death of one of the two partners in the confined aquarium spaces.
Risks and Diseases: PHYSICAL risk for the keeper! This is a dangerous fish. Its bites cause amputations or deep lacerations. Tank maintenance must be done by interposing plastic separators (dividers).
Geographic Origin and Distribution
Amazon River basin (Brazil, Guyana, Venezuela). Inhabits deep river beds, where it waits for prey, but does not disdain strong oxygen-rich rapids.
Origin
Amazon, Orinoco, and Guianas
Fish profile
- Temperament
- Semi-aggressive
- The Aimara is legendary for its demonic, unapologetically vicious temperament. It is utterly fearless, routinely attacking maintenance equipment, hoses, and even the keeper's hands through the glass. Its aggressive nature never subsides, making tank maintenance a potentially dangerous task requiring extreme caution. It is truly a 'monster fish' suited only for the most advanced, dedicated, and careful exotic fish keepers.
- Diet
- Omnivore
- The Aimara is a strict, voracious carnivore that preys on whole fish, crustaceans, and amphibians in the wild. In captivity, it should be fed a varied diet of whole frozen fish like tilapia, smelt, and shrimp. It can occasionally be trained to take massive, high-quality carnivore pellets, though fresh meaty foods are preferred. Live feeder fish should be avoided due to the high risk of introducing parasites and disease.
- Life expectancy
- 10-15 years
- The Aimara Wolf Fish is a highly resilient apex predator that can easily live for 10 to 15 years, and sometimes even over 20 years in captivity with proper husbandry. To achieve such a lifespan, they require an extremely spacious aquarium with a robust filtration system capable of processing their large amount of organic waste. Maintaining stable, pristine water parameters and preventing stress is crucial to keeping them healthy. A proper diet free from fatty meats also plays a vital role in avoiding organ failure and promoting longevity.
- Adult size
- 100 cm
- The catalog's scalar value is 100 cm. The FishBase SPECIES table (v25.04 snapshot) source reports a maximum adult measurement of 100 cm for this species, recorded as standard length (SL). The taxonomic record consulted is Hoplias aimara (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
- Solitary
- There are no documented or reliable external methods to visually determine the sex of this species. Because they must be kept strictly solitary, sexing them is largely irrelevant for the home aquarist. Attempting to house two individuals together to determine sex will undoubtedly end in the immediate death of the weaker fish. Professional DNA testing is the only definitive way to know the gender.
- Feeding frequency
- Twice daily
- Juveniles should be fed once a day to support their incredibly rapid growth rate. Mature adults possess a slower metabolism and only need to be fed large meals two to three times a week. Overfeeding adults can lead to severe health issues like fatty liver disease and poor water quality. Care must be taken when feeding, as they strike with explosive, unpredictable speed and can injure the keeper.
- Bioload
- This massive apex predator produces a tremendous bioload due to its purely carnivorous diet and immense adult size. Exceptional, oversized mechanical and biological filtration is absolutely mandatory to keep the water clean. Frequent, large-scale water changes are required to process the heavy ammonia output from its high-protein meals. An enormous aquarium volume is necessary to dilute the waste it constantly generates.
- Flow
- Stagnant
- It hails from fast-flowing rivers and rapids in South America, preferring highly oxygenated, turbulent waters. Powerful water pumps and wavemakers are highly recommended to simulate its natural, highly oxygenated riverine habitat. Strong current also provides essential physical exercise, preventing the fish from becoming lethargic and obese in captivity. Despite the strong flow, it still requires heavy, secure hiding spots made of large driftwood.
- Reproduction
- Oviparous
- Breeding the Aimara wolf fish in captivity is virtually unheard of due to their extreme aggression and massive size requirements. In the wild, they are believed to be substrate spawners that fiercely guard their nest and fry. Replicating the seasonal flooding and massive territories required for breeding is impossible in a home setting. All specimens found in the aquarium trade are wild-caught from South American rivers.
- Compatibility & tankmates
- It is extremely aggressive, highly territorial, and possesses incredibly powerful jaws equipped with sharp teeth. It is entirely intolerant of tank mates and will actively hunt, kill, or severely maim anything else placed in its tank. It must be kept completely alone as a solitary specimen in a dedicated species-only enclosure. Attempting to house it with other fish, regardless of their size, inevitably leads to disaster.
- Tank level
- Middle/Bottom
- It operates predominantly as a benthic ambush predator, spending the vast majority of its time resting on the substrate. It will stubbornly claim a specific cave or piece of large driftwood as its central lair. From this lower vantage point, it surveys the tank and explodes upward to strike at food. Once a meal is secured, it immediately returns to the bottom to rest and digest.
Scientific Parameters & Models
Window to the official scientific data of the species
Data synced on: 06/15/2026
- Trophic level
- 3.7 ± 0.55 se
- Resilience
- Medium (1.4 - 4.4 years)
- Phylogenetic uniqueness (PD50)
- 0.5
- Bayesian Length-Weight
- a = 0.00741, b = 3.13
- VulnerabilityHigh to very high vulnerability (73 / 100)
Image gallery
Licensed images linked to the species or, when marked, to the closest representative taxon.
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