Hoplo Catfish (Megalechis thoracata): Ultimate Care Guide


The Hoplo Catfish (Megalechis thoracata) is a medium-sized catfish, native to the South American tropics. They are hardy fish with a striking appearance, making them a favorite among those who have kept them. They are great for medium to large size aquarium setups. Preferring to dwell near the bottom of slow moving waters, Hoplo Catfish scour the beds of tropical rivers of the Amazon. 

Although there are albino species, the Hoplo Catfish usually sports an earthy brown coloring that darkens with age. Its abdomen is white, and irregular black spots cover it from barbels to tail.  The Hoplo Catfish gets its name from its original genus, hoplosternum, from the Greek meaning “shield chest.” In 1997, it was categorized into a smaller genus, megalechis, from the Greek meaning “large plate.” Both names are quite suitable for this heavily armored fish.

Hoplo Catfish Care

Hoplo Catfish are hardy fish that is relatively easy to take care of. They will thrive in most tropical aquarium setup that is well-maintained.

Hoplo Catfish typically grow up to 6 inches (15cm) in the wild. However, they can grow up to 8 inches (20.3cm) in an aquarium. In captivity, the reliable food intake allows them to grow larger.

In their natural habitat, they often dwell in murky water and their thick armor gives them excellent protection from many larger species.  Therefore, Hoplo Catfish can live comfortably among some of the more aggressive Cichlids such as the Texas Cichlid, Oscar fish, and Flowerhorn Cichlid. If they find themselves in poorly aerated water, they can absorb oxygen through their intestine, so it is common for them to rise to the surface and take a gulp of air. Hoplo Catfish are not particularly susceptible to disease, and they will thrive in an aquarium environment for many years.

Hoplo Catfish (Megalechis thoracata)
Hoplo Catfish (Megalechis thoracata)

Water Parameters for Hoplo Catfish

Since they are tropical, the ideal temperature for Hoplo Catfish is between 72–86 °F (22–30 °C).  However, due to their hardiness, the Hoplo Catfish can acclimatize to a wide range of temperatures, making them versatile tankmates for many other species.  It is not uncommon for people to keep them in water as low as 64 °F (18 °C).  The hardiness of Hoplo Catfish extends all water parameters; they can thrive in a pH from 5.8 to 7.5 and tolerate hardness up to 20 °H. 

Tank Setup for Hoplo Catfish

Hoplo Catfish prefer spacious tanks, so owners should consider keeping them in aquariums between 25 and 50 gallons (95 and 190 liters).  Although they are not aggressive, excessive crowding may cause them to chase away other bottom-dwelling tankmates.  Furthermore, Hoplo Catfish prefer schools, and it is not uncommon to keep them in groups of 5 or more.

Since they are bottom-dwellers, Hoplo Catfish need a soft or fine substrate in their aquarium to prevent damage to their barbels, which they use to dig for food.  They are both nocturnal and playful, so Hoplos tend to enjoy aquariums populated with many rocks, caves, and other structures that can double as obstacles and pleasantly shaded hiding places. 

Hoplo Catfish love to dig, so the plants in their habitat should have robust root structures as plants without them will be prone to fall or float away.  The Hoplo will not damage any plants on purpose, but they can move quite a bit of the substrate when they are in a playful mood.  Anubias and cryptocoryne have the requisite staying power.  At the top of the tank, water lettuce, Amazon frogbit, and other similar floating plants provide excellent shade for the Hoplo Catfish and will encourage more activity during the day.

Hoplo Catfish prefer water that is oxygen-rich and clean, so a high-capacity canister filter may be the best filtration option.  Although a well-aerated aquarium obviates their need to surface for air, Hoplos will still exhibit this behavior even when they are not in their natural habitat, which tends to be muddy.  

Hoplo Catfish Food & Diet

Hoplo Catfish are omnivores and will thrive on almost any available food; indeed, many owners feed them a varied diet including everything from live larvae and crustaceans to regular pellets and wafers.  As bottom dwellers, they revel in digging out the crumbs of food that have sunk past their tankmates.

Hoplo Catfish Lifespan

With a plentiful, balanced diet and well-maintained aquarium, Hoplo Catfish often live more than 10 years in captivity.  This is a sizable increase over their natural habitat, where the water is less clean and there are more natural predators, wherein they typically live from 4 to 6 years.

Breeding Hoplo Catfish

Hoplo Catfish males build a bubble nest at the surface of the water, often attached to one of the surface-dwelling plants, and guard it vigorously.  Guarding the bubble nest is one of the very few times Hoplo Catfish become aggressive, and they will sometimes attack the female if she comes too close; therefore, breeding Hoplos takes careful preparation.

When the Hoplo Catfish are ready to spawn, the male will present a blue or purple-tinged belly.  It is best then to remove other Hoplos from the tank at that point to prevent any aggression and leave the spawning pair alone. 

Hoplo Catfish males prefer a calm area, free from turbulence, to build their bubble nests.  Partially changing the water and dropping the temperature several degrees will encourage the start of construction.  The male Hoplos will attach their bubble nest to floating plants or other soft structures at the surface of the water.  Hoplo Catfish sometimes take several days to build their nest, often cutting pieces of plants from other parts of the aquarium and using them to stabilize the nest.    

After the bubble nest is complete, the pair will approach the nest and move into a T-formation.  The female will deposit her eggs in the nest and the male will fertilize them.  On average, female Hoplo Catfish will produce 150 eggs, but larger females can deposit more than 500.

Once the eggs are fertilized, it is best to remove the female for her safety.  The male Hoplo Catfish will zealously defend their bubble nests, and they could seriously injure or kill the female (or any other fish) if they get too close.  It is not all aggression, however, for the male Hoplos tend to the nest with great care, rescuing any eggs that break away and repairing the structure as necessary.  Hoplo Catfish eggs hatch anywhere between 72 and 96 hours after they have been fertilized.

The Hoplo Catfish male should be separated from the bubble nest once the eggs start to hatch since they have been known to eat the fry.  After a day, when the nutrition from the egg structure has been exhausted, the fry can be fed microworms.

Hoplo Catfish Tank Mates

Hoplo Catfish are technically predators; however, they are very sociable towards any fish that are too big to eat.  Provided they have enough space, the only time they show aggression is during breeding.  Because of their mild-mannered and sometimes gregarious disposition, Hoplo Catfish are great company for a large range of tankmates, but the most common may be large tetra, guppies, and betta fish.  Also, since the Hoplos are so hardy and can fend for themselves, they can even share a tank with aggressive fish like small cichlids and other predators, as long as the aggressive species are not big enough to eat them.

Hoplo Catfish and goldfish are compatible tankmates, and the Hoplos will greedily eat any of the food that the goldfish carelessly let sink to the bottom of the tank.  The hardiness of the Hoplos allows them to tolerate the colder water preferred by the goldfish, though it may not be an ideal environment for a tropical fish.  Nevertheless, many owners keep Hoplo Catfish and goldfish together as tankmates. 

The main thing to consider when seeking tankmates for Hoplo Catfish is relative size.  If it fits in the Hoplo’s mouth, it is too small and may be eaten.  If the Hoplo can fit inside its mouth, it’s too big and may kill the Hoplo.  Other than that, if the Hoplo Catfish can tolerate the water parameters, it can share space with almost any fish.

Where to Find Hoplo Catfish for Sale?

The Hoplo Catfish is fairly rare, so while they sometimes appear at regular pet stores, it is better to seek them out from a fish farm that specializes in tropical fish.  When they are in stock, Hoplo Catfish typically sell for between $20 and $30 and are shipped between 1.5” and 2”. 

Fish Laboratory

With decades of collective fishkeeping experience, we are happy to share the fish care tips that we've picked up along the way. Our goal at Fish Laboratory is to keep publishing accurate content to help fishkeepers keep their fish and aquarium healthy.

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