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

century.

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.

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.

© Johnny Jensen @ 

© Mark Goh

© Michael Huthart