SCOTCAT.COM  

his month we once again return to the family Callichthyidae 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 thoracata was once, 20 or 30 years ago, held in the same esteem as the fancy L-numbers of today's 21st century.

Megalechis thoracata - 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" or "spotted 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.

You may be more used to the name of Hoplosternum thoracatum when this fish was more popular but 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 has now been a second paper on the genus Megalechis (1995) 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 picta possessing a band and thoracata having a spotted caudal fin. M. picta also has bands on the body whereas M. thoracata is spotted.

Megalechis picta - male

Megalechis thoracata - female

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.

Armoured Catfish

Callichthys exaratus, C. personatus, Hoplosternum personatus, H. thoracatum surinamensis,  Megalechis  personata 

Callichthyinae

South America: Amazon and Orinoco River basins, as well as coastal rivers of the Guianas and northern  Brazil.

19.0cm (7½ins)

18-28°C (64-82°F)

Dorsal: 1/8: Anal: 1/6-8: 25-26 bony scutes in the upper lateral series, 23-24 in the lower.

Keeping this species is not too hard. 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 8inchs 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.

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

Anal fin: The median, unpaired, ventrally located fin that lies behind the anus, usually on the posterior half of the fish.
Caudal fin: The tail.
Dorsal fin: The primary rayed fin(s) on top of the body.
Scutes: Bony covering.

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

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

Photo Credits

Top: © Chris Ralph 
Left: © Julian Dignall @ 
Right: © Allan James @