Aquarium Accessories

Irwini catfish – Habitat, Size, Behavior And Diet

irwini catfish

A unique and heavily armored catfish found in the Amazon also known as megalodorus uranoscopus is a specie of thorny catfish which is native to south America, The Irwini catfish is a gentle giant generally found in aquariums, easy -going with other tank mates. And this fish is a good scavenger as it will eat the leftovers at the bottom of the tank. These fish are also harvested for commercial purposes.


This heavy, characteristic bottom-dweller requires a very spacious aquarium with a soft sand substrate. The footprint (length and width) of a tank is much more important than height, so always aim for a tank as long and wide as possible.

Juveniles grow quickly and therefore require a spacious aquarium from the start. Provide hiding places for them such as rock caves and wide bore pvc pipes.

The more hiding places are provided, the more likely the catfish to move about freely, as it will know it has safe places to retreat quickly if it feels the need.

Dim lighting is preferred, but it can be brighter if it is decorated with a strong mother plant such as anubias or java fern, or tied to floating vegetation. A blue moonlight should come on just before the main lights go off will give you time in the evening to watch this catfish’s nocturnal movements in its preferred subdued conditions.

These fish are messy eaters and therefore produce a lot of nitrogenous waste, so running powerful filtration over the aquarium is essential – ideally with 2 or more canister filters, so that if one fails or needs maintenance, there is backup.

Frequent, partial water changes are an absolute must to keep nitrate levels as low as possible. There should be areas of brisk water movement, with calm areas, and there should be a balance of shady retreat and ample swimming space in front of the aquarium.

Make sure your heater has a safety guard installed, as these catfish get used to resting against the heater and can cause serious burns. Despite its adult size, it is a gentle giant that is best kept in groups if space allows.


They can also be trusted with smaller fishes, although to be absolutely sure, these should be at least 25% of the length of the catfish. Good tankmates can include other large, peace-loving catfish, large cichlids such as Oscar, medium- to large-sized barbs, adult myleus/metynnis species etc.


irwini catfish


This fish has many bony plates and up to 15-18 lateral scutes that increases towards the caudal fin.

There is no plate above or below the caudal peduncle. This catfish has two pairs of barbels, one pair of maxillary and one pair of mandibular.


It has an interesting color pattern with dark brown markings on a light brown background. The body and head are covered with dark brown to black spots. This catfish has a speckled pattern in the ventral region, which is dark brown in colour. The fins are irregularly spotted or mottled with black markings. The color of the pectoral fin is lighter towards the base and darker towards the edge. The adipose fin is light brown on the upper edge of the keel and darker towards the base.

Water condition
  • Temperature: 70 – 77 °F / 21.1 – 25 °C
  • pH: 5.5 – 7.5
  • Hardness: 1 – 20°H

How fast do Irwini catfish grow

This species is gregarious which means that an aquarium with base dimensions of 240 cm x 120 cm should be considered a minimum, but in reality, this species is only suitable for public aquaria and an extreme minority of private aquarists.

Behavior and adaptability

Very peaceful and can be combined with many other species in suitably sized systems. Potential tankmates include characids such as Metnis or Mylus spp., cichlids such as Cichla and Geophagus, large loricarids, other similar-sized doridids such as Pseudodorus niger, Potamotrygon or Osteoglossum spp. This species proves to be best when maintained in a specific group and ideally groups of 4 or more should be purchased.

What do irwini catfish eat

Their natural diet includes crustaceans such as aquatic snails, which must be included as part of their captive diet. In the aquarium they will feed on sinking catfish pellets, floating food sticks, whole prawns, earthworms, shredded and whole mussels. They also prefer drab tablet foods.


There are no cases where the species has been bred in an aquarium.

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