Paraguay Eartheater (Gymnogeophagus balzanii)

Geographic Origin and Biotope: Paraná River, Paraguay River and Rio de la Plata basin. Sub-Tropical Fish! Comes from regions where winter is cold and the rivers slow down, drastically lowering temperatures.

Taxonomy and Morphology: Paraguay Eartheater / Balzanii (Gymnogeophagus balzanii). Peculiar shape: an almost spherical round body, compressed and very short. But the iconic aspect is the imposing gibbosity (nuchal hump) that develops on the nape of the males, almost alien.

Social Behavior: One of the most placid Cichlids ever towards other genera. Shy. Builds harem hierarchies (1 Male, 3-4 Females). Mild, will ignore the furious fights of neighboring cichlids, suffering in silence.

Coloration and Sexual Dimorphism: Warm silver/ocher tones, crossed by a fine yellow/blue polka dot "pattern" along the rounded fins. The male is a concentrate of hormones that develops a huge deformed gelatinous "big head" (nuchal hump). Females are smooth and much smaller (12 cm / 5 inches).

Aquarium Setup: Room temperature breeding. The tank (120 cm / 48 inches) mandatorily requires sand (gravel prevents them from eating), smooth rounded stones and sturdy woods. NO HEATER.

Diet and Feeding: Geo-phagous. Spends its life sifting and spitting the bottom sand (which enters and never exits the gills due to their round shape). Administer quality bottom feed and live food. Very prone to intestinal blockage from mammalian-rich diets (beef heart).

Water Quality: MANDATORY "Wintering" period. If kept 365 days a year at 26-28 degrees (79-82°F), it metabolically exhausts itself, getting sick and dying in 12 months. They must spend the winter between 15 and 18°C (59-64°F).

Compatibility and Tankmates: Best companion in temperate subtropical tanks. Perfect with Corydoras paleatus, large Danios, southern Characins like the Buenos Aires Tetra. Totally bullied victim if placed with Astronotus or Jack Dempsey.

Aquarium Reproduction: Exceptional behavioral mix! They lay on a stone (Substrate spawner), but as soon as the eggs hatch (larvae), THE FEMALE takes all the young in her mouth (Larvophile mouthbrooder) like a Geophagus.

Risks and Diseases: Keeping them at stable tropical temperatures is the cause of 90% of deaths from dropsy and bloat. Fish often kept by unaware novices in boiling community tanks.