Blue-bellied Night Wanderer

Geographic Origin and Biotope: Endemic exclusively to a small section of the extreme upper Rio Negro (Brazil). Its habitat consists of very pure, slow black waters (Blackwater) with a totally muddy-sandy substrate, loaded with rotting leaves.

Taxonomy and Morphology: Blue-bellied Night Wanderer (Cyanogaster noctivaga). Very small Characin (max 2 cm / 0.8 inches) described only in 2013. It is a miniature vertebrate. Features disproportionately large eyes, specialized teeth, and is almost completely transparent.

Social Behavior: Highly peculiar: as the name suggests, it is a strictly nocturnal animal. By day it remains invisible and inactive, hidden in root tangles; it comes out at night to forage in large groups in mid-water.

Coloration and Sexual Dimorphism: Almost total body transparency showing the skeleton. Distinguished by a vibrant abdominal sac (stomach/intestines) colored iridescent neon blue. The mature male possesses microscopic bony hooks on the pelvic fins.

Aquarium Setup: Very specific Nano-aquarium (minimum 40 liters / 10 gallons). Strict Blackwater biotope setup: alder cones, peat, dim (or absent) light. Leaves on the bottom and dense tangles of thin branches to offer essential daytime protection.

Diet and Feeding: Nocturnal micro-predator. Feeding in the dark, it hunts small invertebrates. In the aquarium, it must be fed with lights off with newly hatched brine shrimp nauplii, micro-nematodes, copepods, and paramecia. Will not touch classic granular foods.

Water Quality: The most critical aspect. Requires acidic water (extreme pH, 4.5-6.5) and devoid of carbonate and total hardness (pure RO + natural acidifiers). ZERO tolerance towards nitrites and ammonia. Sponge filtering recommended.

Compatibility and Tankmates: Best kept in a species-only aquarium (only them) in groups of 15+ specimens. Any fish larger than 3 cm (1.2 inches) could prey on them. Possibly compatible with Neocaridina shrimp if water conditions match (difficult).

Aquarium Reproduction: Almost entirely unknown in captivity given its rarity and very recent discovery. It is assumed it scatters tiny eggs among dense root vegetation or aquatic mosses during the night.

Risks and Diseases: Will starve to death if fed only during the day or if placed with food competitors. Sudden chemical changes are lethal. Requires a hyper-stable and mature aquarium (rich in micro-fauna to feed on).