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Megalechis picta  (Müller & Troschel, 1848)     

he first month of 2016 and we make a return to the Callichthyidae family but this time not to your ubiquitous Corydoras but to an old friend in the eyes of the aquarist of the more advancing years and a reminder that Megalechis picta known then as Hoplosternum thoracatum (now Megalechis thoracata) was once, 20 or 30 years ago, held in the same esteem as the fancy L-numbers of today's 21st


Megalechis picta = male


Megalechis picta = male

In the 1960's and 70's the catfish that the average U.K. aquarist could only get a hold of were the Corydoras with aeneus and paleatus being the norm with maybe a few other varieties thrown in. Only a few specialist shops were bringing in the more unusual pets such as a few Synodontis when imports from Africa were obtainable and the more common plecs such as the different varieties of whiptails from South America. That is why the "Port Hoplo" alongside Callichthys callichthys were much sought after all these years ago.

You can distinguish between our factsheet of the month and Callichthys callichthys by the shape of the caudal fin with the latter being more rounded and also possessing smaller eyes. The Megalechis genera has had a checkered history as this genus was revised in 1996 by the Brazilian Ichthyologist, Roberto E. Reis, and only Hoplosternum littorale was kept with him creating a new genus for thoracata with a second species added, Megalechis personata. There was a second paper on the genus Megalechis (1997) and what we used to know as M. thoracata is now M. picta. The difference between these two species rests on the pattern in the caudal fin with M. picta possessing a band and M. thoracata having a spotted caudal fin. M. picta also has bands on the body whereas M. thoracata is spotted. There is quite a marked difference between juveniles and adults and some juveniles (as seen in image) are quite attractive. M. personata is now a synonym of M. thoracata.


Megalechis thoracata can be further distinguished from M. picta by the smaller dorsal-fin spine, generally higher number of anal-fin rays (six, rarely five vs. five, rarely four) and mainly by the colour pattern of caudal fin (see Reis et al. 2005). In M. thoracata the base of caudal fin displays a whitish band and the remaining part is dusky or black spotted, while M. picta presents caudal-fin base blackened, with a conspicuous dark bar in the middle and the distal border also blackened, the regions between the blackened bands are clearly whitish yellow.

Megalechis picta = male pectoral spine


Megalechis picta = juvenile


Megalechis picta = male pectoral spine
Megalechis picta = juvenile



Megalechis thoracata

Megalechis thoracata = female


To finalise these two species, the paper by P-Y Le Bail and JHA Mol (2005), discovered after re-examination the holotypes of Callichthys thoracatus and Callichthys longifilis, which were used to describe the species now placed in Megalechis. The fish were found to be those currently known as Megalechis personata, the so-called Tail-bar hoplo. However, since C. thoracatus was described first, it had priority and is a senior synonym. This meant that the scientists needed a new name for the current Megalechis thoracata, and the next available name was Callichthys pictus, making the new name for the fish Megalechis picta.


The above image of Megalechis thoracata showing you the difference between the two species.


Megalechis picta is native from Amazon and Orinoco river basins, as well as coastal rivers of the Guianas and northern Brazil, it has also been found in the upper Rio Paraná basin.

Dorsal: 1/8: Anal: 1/5: 25-26 bony scutes in the upper lateral series, 23-24 in the lower.

Caudal-fin base blackened, with a conspicuous dark bar in the middle and the distal border also blackened, the regions between the blackened bands are clearly whitish yellow.

Aquarium Care

Keeping this species is not too difficult a task. (see below)


They can become quite boisterous in a community setup with their digging and unsettling other fish at night but as long as your other inhabitants are of a decent size and are not "Neon Tetra size", as remember this fish can get to nearly 7inchs in size and a small 1 inch tetra at night may be too much of a temptation to even the most docile of animals. The only time they can get aggressive is if you have a pair and they are in the throes of spawning as the males can get quite tetchy and it is not unknown for a male to kill the female in the quest to produce a family. This does not happen all the time but best to keep a look-out for any aggressive behavior.

This species is a bubblenester with the male building it at the water surface. The female lays her eggs in the nest and the male looks after them. This is the point that you may have to take the female out of the tank as the male may kill it, as they can get aggressive when guarding the nest.

Sexual Differences

To differentiate between the sexes is not too hard. The males posses thicker pectoral spines with minute hairs adorning them and have an orangey colouration when in breeding condition (see top picture) If you can see underneath your specimens you will also see that the female has a broader gap between the thorax plates than the male so as to give room to the swelling which is involved when carrying eggs.


A good quality flake and tablet food. They also relish garden worms and frozen bloodworm.

Glossary of Terms

Caudal fin: The tail.

Dorsal fin: The primary rayed fin(s) on top of the body.

Anal fin: The median, unpaired, ventrally located fin that lies behind the anus, usually on the posterior half of the fish.
Scutes: Bony covering.



Megalechis: Greek, megas, megalos = great + greek, echis, -eos = viper

picta: Painted

Sterba, Gunther; Sterba's Freshwater Fishes of the World vol 1.
Reis, RE, P-Y Le Bail & JHA Mol, 2005. (New Arrangement in the Synonymy of Megalechis  Reis, 1997 (Siluriformes: Callichthyidae). Copeia 2005: 678–682.)

Tencatt, Luiz Fernando Caserta; da Graça, Weferson Júnio and Pavanelli, Carla Simone. 2013. First record of Megalechis picta (Müller and Troschel, 1849) (Siluriformes: Callichthyidae) in the upper Rio Paraná basin, Brazil.
Reis, 1997; New Arrangement in the Synonymy of Megalechis (Siluriformes: Callichthyidae). Copeia 2005: 678-682.

Photo Credits
© Johnny Jensen @ Johnny Jensen's Photographic Library


© Mark Goh


© Michael Huthart

Factsheet 235

Callichthys longifilis, C. pictus, C. sulcatus, C. thoracatus, Hoplosternum orinocoi, H. thoracatum
Common Name:
Port Hoplo, Tail Bar Armoured Catfish
South America: Amazon, Orinoco and upper Essequibo River basins, and coastal rivers of northern Brazil
15.5cm (6¼ins)
18-28°C (64-82°F)
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