Cascarudo, Armored Catfish

Geographic Origin and Biotope: Incredibly widespread in almost all tropical and sub-tropical South America. Absolute ruler of extreme habitats: stagnant swamps, hypoxic oxbows, acidic black waters and even muddy drainage channels. Faces extreme droughts by moving into contiguous pools crawling on the wet mud.

Taxonomy and Morphology: Namesake for its entire family, Callichthyidae (callous/armored fish). Local "Cascarudo". Brutal size of 15 cm (6 inches). Cylindrical body, totally covered by huge horny plates. In addition to normal gills, it swallows atmospheric air absorbing oxygen through the vascularized intestinal tract.

Social Behavior: Crepuscular hermit with slow tones. Extremely static and unsociable; tolerates conspecifics provided they have exclusive hiding places to rest during the daytime. Enters full, explosive and unstoppable nocturnal digging activity.

Coloration and Sexual Dimorphism: Raw "camo" livery: opaque muddy brown confusingly dotted with black and dark green for perfect camouflage in the darkness and debris. Adult males equipped with greatly thickened first pectoral spines equipped with copper/reddish villi or spikes.

Aquarium Setup: Mammoth and tightly covered tanks (world-class escape fish). Needs a thick muddy or fine inert sand bottom to sink into by day. Huge hiding places made of large root calyxes or PVC pipes, and a water surface free from plants to allow aerial respiration.

Diet and Feeding: Broad-spectrum voracious omnivorous scavenger. Crushes snails, huge earthworms, industrial dry bottom food for carnivores, cichlid pellets and dead plant matter. Feed abundantly, preferably in the crepuscular or nocturnal phase.

Water Quality: Indestructible biological "tank". Tolerates 20 as well as 28°C (68-82°F). pH oscillating from 5.5 (black waters) to neutral 7.5. Varied hardness (GH 2-20). However, the excess of putrefaction in a closed tank will result in the chronic poisoning of its own tissues. Clean water makes it flourish.

Compatibility and Tankmates: Ignores fish from the mouth up; however, everything that stays on the bottom and enters its mouth while dredging at night will be crushed (sleeping tiny Tetras or loricariids). Idyllic companion only in mega-tanks for large Cichlids (Oscars, Severum, large Acara).

Aquarium Reproduction: Similar to that of Bettas. The male creates and brutally guards a voluminous bubble nest and plant fragments on the protected surface (under large floating leaves). The post-spawning aggressiveness of the male towards anyone (including the female) forces the latter to be removed.

Risks and Diseases: The only real fatal risk they run is the rubbing and catastrophic rupture of the very long barbels on gravel or volcanic crushed stone beds, resulting in necrosis and malnutrition.