Though wolf fish is considered the most fearsome freshwater, many aquarists soon learned that Hoplias Aimara is actually quite timid.
It is a freshwater species and known by many names such as Anjumara, Tahira, Anjoemara and Anjoemara and most generally Surinam Aimara wolf fish. Though they are commonly called wolffish, it is not actually one species.
What is Hoplias Aimara?
Scientifically, they are part of a characoid sub-family and belong to the genus Hoplias in the family of Erythrinidae .
The sub-family characoid consists of three genera, totaling 16 species.
The largest group is the genus Hoplias which has 11 species (H. aimara, H. australis, H. brasiliensis, H. curupira, H. intermedius, H. lacerdae, H. malabaricus, H. microcephalus, H. microlepis, H. patana, and H. teres) while the genus Hoplerythrinus has three species and genus Erythrinus has two species.
Among the wolf fish family there are many variations. Hoplerythrinus unitaeniatus, the smallest, will reach just over 20cm/8”, while the largest (Hoplias aimara) will reach 130cm/51” and more than 40kg.
They are found across most of northern South America, Brazil, Colombia, Venezuela , Guyana, French Guiana, Suriname and the island of Trinidad in nearly every kind of water but often found in counter-current zones of principal rivers and creeks.
They have two scientific names Hoplias aimara and Hoplias macrophthalmus where Hoplias aimara is more commonly used than the other name.
In Amazonia, the native populations are concerned by high levels of mercury contamination caused by artisanal and small-scale gold mining.
Aimara is considered a good bioindicator for such contamination as they are in the highest level of food webs due to their predatory behavior.
Aimara has an elongated cylindrical shape while the coloring and the number of patches vary from location to location. But they are mainly from brown color to black color.
The definitive ID of Aimara is a vertically elongated dark spot on the opercular membrane or edge of the gill plate.
They are popular as aquaculture fish as well as their flesh among natives.
How big do Hoplias Aimara get?
The Hoplias aimara is considered as the largest of the Hoplias species.
The Average length of fully grown Hopalias Aimara is nearly 30 inches while the length of the largest of this species is 120 cm. The average weight of fully grown was recorded as 40kgs.
Is Hoplias Aimara aggressive?
This species is extremely aggressive and they kill or severely injure nearly any tankmate. Therefore it is advised to keep one fish of this species unless the aquarium is too large.
They are one of the most aggressive fish in the wild as well as in captivity. Though they don’t tend to attack humans, they may attack humans too when provoked.
There are many incidents reported of their aggressive behavior. They had attacked humans defending their territory in the wild.
Especially fishermen avoid them because they destroy their fishing nets with their powerful jaws.
Some aquarists have reported that Hoplias Aimara are more voracious and much more aggressive than piranha.
Hoplias Aimara behavior
They are mainly nocturnal animals as they are active predominantly at dusk and at night. This fish is mainly an ambush predator of fish.
But they also feed opportunistically on other animals that fall into the water such as terrestrial invertebrates.
The wolffish family members are relatively active and like to hover mid-water.
However, they can be very fast swimmers when they identify prey or are provoked by another party.
The Hopalas Aimara has a special ability to breathe air and only an other few fish species have this ability.
Therefore, they can live in low oxygen environments. especially during the dry season, it is not unusual to see they are the last survivors.
How long do Hoplias Aimara live?
Actually, there is no clue how long Hoplias Aimara lives in the wild or in captivity. However, there is some evidence that the other members of Hoplias genus live around 20 years.
One look Care guide
|Scientific name||Hoplias aimara |
|Native to||South America|
|Tank size||300 gallons|
|Prefered temperature||78 to 82 0F|
|Other water parameters (ammonia ,ect)||pH: 6.5 – 7.5|
|Prefered salinity||Freshwater fish|
|Recommended tank mates||Large tank mates Myleus|
Large-bodied cichlids such as Astronotus
Hoplarchus and Cichla
|Prefered food||Live prey|
|Feeding Frequency||Depending on the size |
Specimens in between 11” to 18″every three days
Specimens in between 7” to 10″ need to feed every two days.
Fries and fingerlings everyday
|breeding||Not known in captivity|
Hoplias Aimara care
Hoplias Aimara size
The average size of a fully grown individual of this species is around 30 inches (76.2 cm)while the largest captured record is at 4 feet.
The largest rod and reel record is 101 cm. They will easily reach 50 cm in aquariums and often much more.
It is highly probable that larger specimens will attain sizes of 80 cm and up if the tank is large enough. The average weight of fully grown is around 40kg.
Hoplias Aimara tank size
Since the fully grown individual of this species is comparatively large, it needs a tank with 300 gallons capacity.
However, individuals at over 30cm/12” are found to be difficult to keep in a tank and it is best to keep adults at over 100cm/40” in acrylic tanks or custom indoor ponds .
How many Hoplias Aimara should be kept together?
Though they are one of the most aggressive species they also can be kept together.
They show moderately territorial behavior in normal conditions and if the aquarium size is suitable to keep a pair of them they will display to each other with flared gills and fins.
They rarely bite each other if not provokes and form pairs at 50 cm and harmonize well together.
It is very important to keep ambient environmental conditions because they may become very intolerant to each other due to changes in environmental conditions such as low oxygen environments.
Nevertheless, it is best to keep only a pair in one tank and they should be kept with the supervision of experts who can handle the long-term requirements of these species.
A large open aquascape approximately 300 gallons (240cm x 90cm x 60cm – 96” x 36” x 24”.) should be provided to this species as the wolffish family members are relatively active and like to hover mid-water.
Since they are found in fast-flowing rivers and rapids in nature, they prefer running water and become more active if provided a tank or pond with a good flow.
Their natural habitats are flooded forest areas and rocky rapids. Therefore, it is important to add small & smooth rocks with moss and suitable aqua plants into the tank.
Further, the driftwood can be used to decorate the Aimara tank.
Adding a few dried leaves to the tank can make the tank a little bit similar to their natural environment and it is also advantageous as the leaves release nutrients as they break down.
However, it should be kept in mind to leave plenty of large flat areas for the fish to lie on. Some aquarists suggest considering adding Blackwater to make the environment the same as the Amazon river.
Though they are generally nocturnal animals, they can be easily conditioned to a diurnal state. It can be done by housing them in a tank with dim lighting and plenty of overhead covers.
In addition, a mat of floating plastic plants combined with low lighting also can be used to watch the aimara fish during the day.
They thrive with any combination of pebble, sand, or even lack of substrate, and hence specific substrates are not of paramount importance to this species.
However, since these fish hover in mid-water or just below the surface, the tank depth is not a critical factor.
Hoplias Aimara often hurt themselves due to their reckless and violent behavior especially when they are in captivity.
They get cuts and bruises when they crash into driftwood when chasing prey; tear their fins when they hit the brace or glass cover; or bust their lip when they hit the glass panel.
Although they easily recover from these injuries within a few days even without treatment, it is good not to add any items to the tank with sharp ends.
As these fish attack anything in the tank whether live or inanimate, the commercially available filters will not work for them.
Therefore, custom-made filters are the best option and you should secured other equipment such as tubes, airstones.
You should plan the tank of Hoplias Aimara well before thinking of adding them to the tank because fixing anything after may end up in an injured hand!
Further, since large specimens will even hit the glass of the aquarium, large acrylic ponds will be more suitable for large specimens.
Water quality condition
Hoplias Aimara prefers fast-moving water to other wolf fish species. Therefore, they can be more sensitive to bad water conditions.
Though they can survive in low oxygen environments as they can breathe air, they can be very aggressive towards other individuals when there is a pair of them in the same tank.
Their preferred pH range is between 6.5 to 7.5 while the preferred temperature range is between 78 to 82 0F .
Both the Ammonia and Nitrite concentration should be at 0 ppm. The Nitrate level should be <30 ppm.
Since the Hoplias Aimara is a messy eater the aquarium will also need to have a good water filter.
They attack the prey instantly and due to their massive jaws and sharp teeth, scales and bits of meat will be scattered everywhere; thus to keep the water quality constantly strong filtration is essential.
You should change water once a week about 15%-20% as they tend to live in waters with high flow and tend to have higher pH. After the changing of water pH and other parameters should be checked.
Hoplias Aimara breeding
Hoplias Aimara male or female identification
Many studies revealed that Hoplias aimara shows sexual dimorphism in the morphology of the anal fin. And their gender identification is possible by careful inspection.
In males, when the anal fin is projected forward of the fish body, its surface takes the form of a spoon or a shell.
This form of the spoon may be more or less concave but in males, its surface never remains flat. In females, when the anal fin is projected forward of the fish body, it remains flat surface.
Moreover, Female Giant Wolffish are slightly heavier in build than their male counterparts.
Identify pregnant Hoplias Aimara
As they mature, females develop a more robust shape and rounded stomach and it is the first signal that they are ready for reproduction.
Hoplias Aimara breeding
Hoplias Aimara’s reproduction takes place at the onset of the rainy season from December to March in their natural habitats and depending on the size, the female can carry around 6,000 to 60,000 eggs.
When they become mature and ready for breeding, They will become increasingly intolerant until a pair has formed, they will usually get along well and lay close together.
In their natural environment male digs shallow pits and the female puts eggs in it in a cluster. The eggs are yellowish. You can introduce captivity breeding by first dropping the temperature, raising it to 28-29°C/82-84°F and slightly dropping the level of water.
The male guards the nest and larvae. They continuously guard the nest until they hatch and spread out in the shallow water to hunt small prey.
However, breeding in captivity is less known but definitely needs a huge aquarium. As reproduction takes place in captivity is very rare, they are very expensive.
How many babies does Hoplias Aimara have?
They are a very productive species and known to have 10,000 fries at a time.
But due to their very aggressive and predatory nature, they tend to eat and kill themselves and it is better to put them in different tanks based on their size.
They are growing very fast and it takes only six months to grow up to 1 foot.
Hoplias Aimara fry care
They are omnivorous during their fry and juvenile stages and can feed anything available.
But make sure to feed them with a balanced diet. Juveniles are usually lighter and have bright yellow or green eyes.
All wolffish are excellent jumpers and any aquarium must be covered at all times.
The tank maintenance is quite difficult because they can bite the tank keeper, by the sharp teeth of their powerful jaws by Hoplias Aimara.
Moving adults also a dangerous task, because the fish will bite even out of the water. Their sharp 3cm/1.2” long teeth are famous to penetrate most gloves and you should take special arrangements before thinking of moving them.
Transportation of individuals of this species is also very hard as they can easily break plastic containers use for fish transportation.
Feeding behavior of Hoplias Aimara
What do they eat
Although they are defined as Piscivores in much literature they eat nearly anything which falls into the water including insects in the wild.
However, small fish are the main diet of Aimara in the wild. In aquariums, they attempt to eat any other fish with their large and fearsome mouths including large loricariids, which their powerful jaws can break apart.
However, according to many aquarists they love to eat live prey but will accept dry foods such as pellets, freeze-dried shrimp and insects, and sometimes even flake foods more readily than their relatives. Then even can be fed with meat leftovers too.
According to many aquarists, it is very important to feed them with live food at least once a week as they are predatory fish.
How often should you feed
As they are predatory fish, there is no need to feed them every day and the time period you need to feed depends on their size.
For specimens in between 11” to 18″ need to feed every three days and specimens in between 7” to 10″ need to feed every two days.
Anyway, need to make sure not to overfeed as it is not good for their health as well as the water quality of the aquarium.
When should you feed (time of the day)
As they are considered nocturnal fish, it is best to feed them at night or when it is dark.
How long they can go without food
They can stay without food for a certain time period as they are predators and do not hunt every day even in their natural environment.
Some aquarists have complained that they do not eat for 5 days after they are introduced to a new tank.
Most of them will begin to have their regular meals after some days when they are used to the new environment.
What fish can live with Hoplias Aimara?
Since Hoplias Aimara is a very aggressive and predatory fish their community must be decided after careful consideration.
They usually ignore the fish that do not challenge them for the territory or do not fit in their mouth.
Therefore, ideal tank mates are sturdy characins such as Myleus and Metynnis. Large-bodied cichlids such as Astronotus, Hoplarchus and Cichla also fare well.
Slow catfish risk having their eyes bitten when entering caves occupied by wolves