January Tetra (Hemigrammus hyanuary) Breeding Guide

Hemigrammus hyanuary males show an anal-fin hook; pairs spawn overnight in dark soft acidic water, with light-sensitive eggs hatching in 24-36 hours.

Overview

Hemigrammus hyanuary, the January tetra, comes from the Amazon basin of Peru and Brazil, including Lake Hyanuary near Manaus, and reaches about 4 cm. Seriously Fish documents a full egg-scattering spawning protocol; the species shows no parental care.

Sexing

Adult males are slightly smaller and noticeably slimmer than females, and the male carries a small hook on the anal fin, which the female lacks. Conditioned females are also visibly rounder.

Conditioning

Condition the fish with plenty of small live foods. For pair spawning, condition the sexes separately, then select the fattest female and best-coloured male. General care parameters are 23-27 C, pH 6.0-7.0 and hardness 2-15 dH.

Breeding Setup

Seriously Fish recommends an 18 x 10 x 10 inch tank with very dim lighting, fine-leaved plants such as java moss or spawning mops, or a mesh-covered base. Spawning water should be pH 5.5-6.5, gH 1-5 at around 80-84 F, with peat filtration and RO water recommended and a gently bubbling sponge filter.

Spawning Behavior & Trigger

Spawning can be done in groups of six of each sex or in pairs. For pairs, transfer the selected fish in the evening; they should spawn the following morning.

Egg & Fry Care

Eggs hatch in 24-36 hours and fry become free-swimming 3-4 days later. The eggs and fry are light-sensitive in the early stages of life. First food is an infusoria-type food, progressing to microworm or brine shrimp nauplii.