Green Neon (Hemigrammus hyanuary) aka January Tetra

Green Neon (Hemigrammus hyanuary)

Green Neon (Hemigrammus hyanuary)

The Green Neon (Hemigrammus hyanuary) known to tropical fish keeping enthusiasts as the January Tetra or Costello Tetra is found in the Amazon River basin in Brazil and Peru; specifically Lake Hyanuary near Manuas, Brazil.

Green Neons are an active shoaling species that are found in the black waters of slow moving rivers, river tributaries and seasonally, the floodplains of lakes.

Green Neon (Hemigrammus hyanuary)

Green Neon (Hemigrammus hyanuary)

The Green Neon has a silver to olive green body with a yellow to green iridescent stripe that extends from the snout to the base of its caudal fin. A black band below the stripe extends from the tail to mid way on the body.   It has transparent fins and a silver to orange colored patch directly above the stripe at the base of the tail.

Although they are often confused with the more common head and tail light tetra, H. ocellifer; adult Green Neon tetras have a bright green colored iris.

Adult male Hemigrammus hyanuary have a small hook on the anal fin and are a bit smaller and noticeably slimmer than females.

Green Neon tetras are perfect candidates for a blackwater biotope setup with at least 6 or more of their own kind.  They are best housed in at least a 10 gallon tank with a sandy or very fine substrate, some driftwood branches, and some dried Indian Almond, Beech, or Oak leaves to replicate their natural waters.  Submerged plants are optional.  A peat bag added to the filtration system can alternately be used to simulate the weak tea colored waters that they are found in.

Some small floating plants like duckweed, can be added to diffuse overhead lighting and mimic the dimly lit conditions they prefer.   Frequent water changes are recommended.

Be sure to replace the dried leaves every couple of weeks, so they don’t foul the aquarium water.

Green Neon tetras can be housed in a community tank environment with other small, peaceful, South American species. Suitable candidates are other species of Hemigrammus or Hyphessobrycon, pencil fish, smaller rasboras, barbs, dwarf Apistogramma or Pelvicachromis species cichlids, Corydoras, and small Loricariids.

Green Neon tetras are often bred in an aquarium environment similar to other tetra species.

Set up a small, dimly lit breeding tank with spawning mops or fine leaved plants like Java Moss to give the fish a place to deposit their eggs and a small air powered sponge filter. The water needs to be at a pH of 6.0, 4 dH, and a temperature from 79-84°F. Peat bags or Indian Almond leaves can be used but are not necessary.

Green Neons can be spawned in groups or in pairs.

Place 5 or 6 pairs of Green Neons that have been conditioned with feedings of small live foods into a breeding tank and let nature take over.   The fish will spawn in the early morning hours.

When breeding pairs, condition several fish and select the fattest egg filled female and a male that displays the best color and place them in the breeding tank during the evening.   The pair should spawn early the next morning.

Both parents will eat their eggs when given the chance and should be removed from the breeding tank as soon as the eggs are observed.   The eggs will hatch out in 24 to 36 hours and the fry becoming free swimming a 3 to 4 days later.

For the first few days, the fry should be fed infusoria until they grow large enough to accept baby brine shrimp, microworms, finely crushed flake food, etc. Because the fry are light sensitive, keep the rearing tank dark during the first few weeks of growth.

Professional breeders cover the bottom of a bare tank with a fine mesh large enough for the eggs to pass through, yet small enough so the adults cannot reach them.

In their natural habitat, Green Neons (Hemigrammus hyanuary) feed on small invertebrates.   In an aquarium environment, they are not fussy eaters and should be fed a balanced diet of dried flake food with live, frozen, or freeze dried aquatic insects, brine shrimp, daphnia, bloodworms, Tubifex, etc.

Most Green Neons (Hemigrammus hyanuary) available to tropical fish keeping enthusiasts are captive bred in Singapore Malaysia. They are occasionally available for purchase from specialty fish shops and online from a variety of sites when they are 3/4″ to 1-1/2″ in size.

When kept in alkaline conditions, Green Neons will lose their coloration.

Green Neon (Hemigrammus hyanuary)

Green Neon (Hemigrammus hyanuary)







Minimum Tank Size: 10 gallons
Care Level: Moderate
Temperament: Peaceful
Aquarium Hardiness: Hardy once acclimated
Water Conditions: 74 to 82 °F , dH 6-15, pH 6.0-7.5
Max. Size: 1.6″
Color Form: Silver, Yellow, Green
Diet: Omnivore
Compatibility: Peaceful, keep with other small tetras
Origin: Lake Hyanuary, Farm Raised in Singapore
Family: Characidae
Lifespan: 5 years
Aquarist Experience Level: Beginner

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