Blue emperor tetra

Geographic Origin and Biotope: Rio Aripuanã Basin (Brazilian Amazon). Populates the slow-flowing inlets shaded by the dense rainforest, on bottoms of sand and fallen branches.

Taxonomy and Morphology: Blue Emperor Tetra (Inpaichthys kerri). The only member of its genus. Often confused with Nematobrycon palmeri, it is distinguished by the presence of the dorsal adipose fin (absent in palmeri).

Social Behavior: Very lively schooling fish and formidable swimmer. Males engage in continuous, harmless fights parrying with spread fins to dominate the attention of the females of the school.

Coloration and Sexual Dimorphism: Cobalt Blue. Males (more slender) show a bright bluish lateral band on a purplish/lavender background; females are stockier, yellowish-gray, with a black band. The blue lights up only in acidic water.

Aquarium Setup: 80 cm (32 inches) tank. Requires ample space for horizontal free swimming in the center and a dense barrier of plants on the sides. Submerged roots and dim light will make their otherwise dull livery explode.

Diet and Feeding: Voracious micropredator. Hunts insects in mid-water. Excellent eater of live daphnia, bloodworms and brine shrimp. Immediately accepts fine dry granules for characins.

Water Quality: Tolerates a medium GH, but to show the "Blue Emperor" reflection strictly requires a pH below 6.8 and water filtered with active granular peat.

Compatibility and Tankmates: Excellent community fish. Unlike some nippy tetras, it ignores its companions (does not bite long fins). Ideal with Apistogramma, Corydoras and bottom Loricariids.

Aquarium Reproduction: Egg scatterer. In the morning, the couple side by side releasing non-adhesive eggs in the moss (Taxiphyllum). Once the parents are removed (they would eat them), the eggs hatch in 24 hours.

Risks and Diseases: Visual Stress Pallor. If kept in bare tanks, too illuminated (without floaters) or on blinding white gravel, the fish deactivates the chromatophores, resulting in mouse gray for its entire life.