Axelrod's glass tetra

Brittanichthys axelrodi

Also known as Red glass tetra, Painted glass tetra

FreshwaterFish

Care at a glance

Temperature: 75–82°F (24–28°C)
pH: 4.5–6.2
Adult size: 1.3 in (3.3 cm)
Minimum tank: 14 gal (54 L)
Temperament: Peaceful
Social behavior: Schooling
Swim level: Middle
Difficulty: Difficult
Breeding: No record
Rarity: Rare
Origin: Rio Negro blackwaters, Brazil
Family: Characidae

Overview

This is a tiny, delicate blackwater tetra that needs a group, so keep at least eight to ten together to see natural behavior and steady color. It swims in the middle of a quiet, dimly lit tank and is entirely peaceful, best kept in a species tank or with equally small, gentle companions from the same soft, acidic water, such as cardinal tetras and pencilfish. Nothing boisterous or fast should share the tank, since it competes poorly for food. Offer tiny foods: microworm, baby brine shrimp, cyclops, and finely crushed flake. A group does well in around 54 liters or more, mature and stable.

In the wild

Brittanichthys axelrodi comes from the blackwaters of the Rio Negro in Brazil, tea-stained streams that are very soft and strongly acidic, often near pH 4 in nature. To keep it well you need genuine blackwater conditions: warm water from 24 to 28 degrees Celsius, pH held low between 4.5 and 6.2, and very little hardness. Filter over peat or botanicals, add leaf litter and driftwood for tannins, dim the light, and keep the tank mature and stable.

Good to know

A miniature characin of about 3.3 centimeters, Brittanichthys axelrodi is one of the inseminating tetras: instead of fertilizing eggs in open water, males transfer sperm directly to females, which can then store it. Mature males carry tiny bony hooks on the anal fin and a distinctively curved caudal-fin ray tied to this mating system. The genus name honors ichthyologist Martin Brittan and the species Herbert Axelrod. Home breeding is essentially undocumented.

Did you know

It is one of the few tetras that reproduces by internal insemination rather than external egg fertilization, with males using hooked fin rays as contact organs during mating.

Tank mates

Axelrod's glass tetra is a peaceful, schooling species that keeps to the middle. These picks match on water type, temperature, pH, size and temperament.