Anduze's Pencilfish

Geographic Origin and Biotope: Upper Orinoco (Venezuela) and Rio Negro (Brazil). Pure Blackwater micro-environments. Resides exclusively at the very slow margins of dark pools in the midst of inextricable roots.

Taxonomy and Morphology: Anduze's Pencilfish (Nannostomus anduzei). The smallest Pencilfish in existence. A 1.5 cm (0.6 inches) projectile with a snout as sharp as a pin. Lacks an adipose fin.

Social Behavior: Hyper-gregarious static. Hovers in mid-water, moving in millimetric jerks like its larger cousins, but its fragility forces it to form a fixed school (min 15-20 specimens) among the leaves.

Coloration and Sexual Dimorphism: Red Spark (Dwarf Red Pencilfish). A gold/brown lateral band runs along the flank. Males show a patch of intense carmine red on the anal and caudal fins (which are almost completely lacking in the round females).

Aquarium Setup: Nano-tank biotope or highly specialized community aquarium. Fine sand, dim light, peat to darken the water, dry leaves on the bottom and total absence of rushing currents. Abundant moss.

Diet and Feeding: Micro-planktivore. The mouth is so invisible that it struggles to eat any crumbled dry food. Only live or decapsulated brine shrimp nauplii, infusoria, and microworms (vinegar eels) will guarantee its survival.

Water Quality: Very fragile against nitrogen peaks. Being wild and tiny, it requires reverse osmosis water cut with minimal salts (TDS below 50), decidedly acidic pH (5.5) and zero thermal swings.

Compatibility and Tankmates: Ghost fish in a mixed community. Will disappear into the belly of angelfish or large tetras in a second. Coexistence strictly limited to Boraras, Corydoras pygmaeus and Otocinclus.

Aquarium Reproduction: Extremely rare, microscopic eggs dispersed among the moss. The fry take days to absorb the yolk sac and need live paramecia for weeks before they can target a nauplius.

Risks and Diseases: Competitive starvation. They often die not from diseases, but because they cannot reach the food before normal tetras, disappearing one after another within a month of purchase.