The South American pufferfish Colomesus asellus (a recent study shows that, based on genetic analysis, the genus Colomesus should be considered a synonym of Sphoeroides; the species should therefore correctly be designated as Sphoeroides asellus) are ideal for aquarium keeping. They remain small (usually around 6–8 cm, at most around 12 cm; other size claims are based on misidentification), are strictly freshwater species, love to eat small snails, and are completely peaceful, both toward conspecifics and other fish species. They have only one trait that counts against them: they are incredibly active and dart around the aquarium nonstop. Under no circumstances should they be kept with fish species that prefer quiet, and even nervous aquarists should steer clear of them.
Special care is needed during the acclimation period: Colomesus are highly susceptible to Piscinoodinum and Ichthyophthirius (velvet and white spot disease). These diseases can be effectively treated with commercially available medications; additionally, raising the temperature to 30°C and using a flow pump can help. Once acclimated, however, the fish are hardy and long-lived, and their playful nature brings a lot of joy.
We source these fish from the upper Amazon, mostly from Peru, but sometimes also from Colombia or Brazil. Incidentally, a look-alike species was described in 2013 from the Rio Tocantins basin in Brazil; it is virtually indistinguishable from S. asellus in color, but differs in minor anatomical details and, most notably, based on DNA: Sphoeroides tocantinensis. This species is also a strictly freshwater pufferfish. To the best of our knowledge, it is not exported, and its care should not differ from that of S. asellus, but it’s good to know that it exists.
For our customers: Sphoeroides asellus is listed on our stock list under codes 218301 (1 cm) through 218306 (10–12 cm), depending on size. Please note that we supply exclusively to wholesalers.
Literature:
Araujo, G. S., Y. R. Kurtz, I. Sazima, P. H. Carvalho, S. R. Floeter, A. Vilasboa, M. M. Rotundo, C. E. L. Ferreira, J. P. Barreiros, D. E. Pitassy & A. Carvalho-Filho (2023): Evolutionary history, biogeography, and a new species of Sphoeroides (Tetraodontiformes: Tetraodontidae): how the major biogeographic barriers of the Atlantic Ocean shaped the evolution of a pufferfish genus. Zoological Journal of the Linnean Society v. 199 (no. 4): 978-993
Text & Photos: Frank Schäfer
