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Iain Briggs (4) Steven Grant (1)

Description: Dorsal spines (total): 1; Dorsal soft rays (total): 7; Anal soft rays: 12 - 15; Vertebrae: 43 - 45. Vertebrae including the Weberian complex. Dorsal profile of head and nape convex from snout tip to vertical at posterior nostril, then nearly straight to origin of dorsal fin, scarcely convex along dorsal-fin base, then less convex to posterior insertion of adipose-fin, and gently concave across caudal peduncle. Ventral profile slanting convexly ventrally from snout tip to end of gill region, slightly convex to straight to pelvic-fin origin, stepped dorsad posterior to pelvic girdle, then convex onto anal-fin base, slanting dorsally to caudal peduncle and concave along caudal peduncle. Aquarium Care: A tank of at least 3ft x 18ins x 18ins with a medium water flow and weekly water changes. Diet: Wormfoods, shellfish and other meaty or insect-based foods. Etymology: The specific name orixanthum: Reference to the distribution of the species in the Orinoco basin and its relationship to the species Megalonema xanthum. Remarks: For more information on this species and genera read the paper by Lundberg, J.G. and W.M. Dahdul, 2008 and the catfish book by Steven Grant (2021) on Pims which are referenced below.

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Pimelodidae

South America: Orinoco River basin in Colombia and Venezuela.

12.0cm. (4¾ins)

22-27°C (71-81°F)

6.0-7.2.

Lundberg, J.G. and W.M. Dahdul, 2008. Two new cis-Andean species of the South American catfish genus Megalonema allied to trans-Andean Megalonema xantum, with description of a new subgenus (Siluriformes: Pimelodidae). Neotrop. Ichthyol. 6(3):439-454.
Grant; Steven, pers comm. Dec. 2013.
Grant, Steven. Pims. Pimelodidae, Heptapteridae and Pseudopimelodidae Catfishes. ATS-Aquashop.de 2021 219p.
Villa-Navarro, F., DoNascimiento, CD, Mojica, J.I., Rodríguez-Olarte, D., Taphorn, D.C. & Herrera-Collazos, E.E. 2021. Megalonema orixanthum. The IUCN Red List of Threatened Species 2021.