From the drainage of the Rio Tapajós (tributaries in the Jacareacanga region, state of Pará, Brazil) comes a very interesting armored catfish that was not officially described until 2025: Hoplisoma noxium. The large number of CW numbers assigned to this species prior to its description already suggests that the species is highly variable in coloration.
The combination of characteristics—1. a dark eye band; 2. light spots on the head and anterior body; and 3. a dark spotted pattern on the flanks, dorsal fin, and caudal fin—is unique among armored catfish. All specimens exhibit this combination of characteristics, but hardly any two individuals are alike.
It is interesting and worth noting that this armored catfish species (and several others) could only be scientifically studied thanks to an expedition by ichthyologists working in Brazil, which was funded by private donations from interested hobbyists. As has so often been the case, this demonstrates once again that aquarium science is a fundamental building block for species identification in small fish. This is an indispensable foundation for species conservation, because without species knowledge, there can be no species conservation.
The species name “noxium” means—very loosely translated—“the one with the potent toxin.” When under stress, this armored catfish species can secrete a powerful toxin that kills all the fish in the transport container. This must be taken into account during transport, and appropriate precautions must be taken.
Maximum size: approx. 6–7 cm; Temperature: 22–28°C; pH and hardness: not important for general care (tap water), but soft and acidic for breeding; Diet: omnivorous; Social behavior: peaceful schooling fish.
We’ve also created a short video about these fish, which you can watch here: https://www.youtube.com/watch?v=AhFgE85ReDA
For our customers: These fish are listed under code 236262 on our stock list. Please note that we supply exclusively to wholesale customers.
References:
Tencatt, L. F. C., W. M. Ohara, V. Carvalho, S. Grant, and M. Britto (2025): Two exquisite new species of Hoplisoma (Siluriformes: Callichthyidae) from the Rio Tapajós basin, Brazil, with a discussion on the morphology of the mesethmoid within Corydoradinae. Neotropical Ichthyology vol. 23 (no. 1): e240100: 1–76.
Text & photos: Frank Schäfer
