Black Widow Tetra 2–4cm

Description

Black Widow Tetra (Gymnocorymbus ternetzi)

Hardy, active and instantly recognisable, the Black Widow Tetra is a classic South American schooling fish with a deep-bodied profile, dark vertical bands and contrasting black fins. Kept in a proper group, Gymnocorymbus ternetzi is an energetic and dependable community fish that suits a wide range of established freshwater aquariums.

Quick Facts

  • Scientific name: Gymnocorymbus ternetzi
  • Common names: Black Widow Tetra, Black Skirt Tetra
  • Origin: South America
  • Adult size: Approximately 5–6 cm
  • Tank size: 60L+ recommended
  • Difficulty: 🟢 Easy
  • Temperament: Generally peaceful and active
  • Swimming level: Midwater
  • Best kept: Groups of at least 6, with 8+ preferred where space allows

Is this for you?

✔️ Perfect if:

  • You want a hardy schooling tetra.
  • You enjoy active community aquariums.
  • You prefer bold black and silver contrast.
  • You want a straightforward species for a newer aquarist.
  • You have enough room for a proper group.

❌ Avoid if:

  • You intend to keep only one or two individuals.
  • Your aquarium is too small for an active school.
  • You keep very slow-moving or delicate long-finned fish.
  • You want a solitary centrepiece species.

Why choose Black Widow Tetras?

Black Widow Tetras are long-established favourites because they combine strong visual contrast with hardy, adaptable behaviour.

Their deep silver-grey body is marked by distinctive dark vertical bands, while the dorsal and anal fins can develop rich black colouration that looks especially striking in a planted aquarium.

They are active schooling fish and become much more confident when kept in a proper group.

The species is also forgiving of a reasonably broad range of water conditions once established, making it a reliable choice for community aquariums.

Benefits

  • Hardy and beginner friendly
  • Distinctive black and silver colouration
  • Active schooling behaviour
  • Generally peaceful temperament
  • Easy to feed
  • Adaptable once established
  • Excellent for planted community aquariums

Care made simple

  • Temperature: Approximately 20–26°C
  • pH: Approximately 6.0–7.5
  • Water: Clean, stable and well oxygenated
  • Diet: Omnivorous
  • Staple foods: Quality flakes and appropriately sized pellets
  • Supplement with: Brine shrimp, daphnia and bloodworms
  • Flow: Gentle to moderate
  • Setup: Plants around the sides and rear with open swimming space
  • Regular water changes help maintain strong colour and condition.
  • Keep in a proper social group.

Pairs perfectly with

  • Other peaceful tetras
  • Rasboras
  • Corydoras
  • Small peaceful loaches
  • Gouramis
  • Other peaceful community fish of a similar size
NTA Insight:
Black Widow Tetras are much better fish in a group than they are as single specimens. Six should be treated as a practical minimum, while a larger group gives you more natural schooling, better confidence and less chance of one fish repeatedly bothering the same tank mate.

FAQ

What is the scientific name of the Black Widow Tetra?

The accepted scientific name is Gymnocorymbus ternetzi.

Is the Black Widow Tetra the same as the Black Skirt Tetra?

Yes. Black Widow Tetra and Black Skirt Tetra are common names used for Gymnocorymbus ternetzi.

How large do Black Widow Tetras grow?

Adults generally reach approximately 5–6 cm.

How many should I keep?

Keep at least six, with larger groups preferred where aquarium size allows.

Are Black Widow Tetras peaceful?

They are generally peaceful community fish when kept in a proper group, although normal chasing and social sparring can occur.

Do Black Widow Tetras nip fins?

They can occasionally nip slow-moving or long-finned tank mates, particularly when kept in groups that are too small. A proper school helps direct their social behaviour toward one another.

What should I feed them?

Offer quality flakes or small pellets as a staple and supplement with live or frozen foods such as brine shrimp, daphnia and bloodworms.

Can Black Widow Tetras live with shrimp?

Adult shrimp may coexist with them in a well-planted aquarium, but small shrimp and shrimplets should be considered potential food.

Do Black Widow Tetras need a heater?

A heater is usually recommended where room temperature is not consistently within their preferred range.

Can Black Widow Tetras breed in aquariums?

Yes. They are egg-scattering fish and provide no parental care, so adults may eat eggs and fry unless a dedicated breeding setup is used.

Are Black Widow Tetras suitable for beginners?

Yes. Their hardiness, straightforward feeding requirements and adaptable nature make them a good beginner community fish once the aquarium is properly cycled.

How long do Black Widow Tetras live?

With clean water, good nutrition and appropriate social conditions, they commonly live for around 3–5 years and sometimes longer.

Black Widow Tetra 2–4cm

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SKU: 22005

📍 In-Store Locations: OFFLOCATION1
📦 Arrival Date: 14 August 2026

20 in stock  

$7.95


All prices include GST
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    Description

    Black Widow Tetra (Gymnocorymbus ternetzi)

    Hardy, active and instantly recognisable, the Black Widow Tetra is a classic South American schooling fish with a deep-bodied profile, dark vertical bands and contrasting black fins. Kept in a proper group, Gymnocorymbus ternetzi is an energetic and dependable community fish that suits a wide range of established freshwater aquariums.

    Quick Facts

    • Scientific name: Gymnocorymbus ternetzi
    • Common names: Black Widow Tetra, Black Skirt Tetra
    • Origin: South America
    • Adult size: Approximately 5–6 cm
    • Tank size: 60L+ recommended
    • Difficulty: 🟢 Easy
    • Temperament: Generally peaceful and active
    • Swimming level: Midwater
    • Best kept: Groups of at least 6, with 8+ preferred where space allows

    Is this for you?

    ✔️ Perfect if:

    • You want a hardy schooling tetra.
    • You enjoy active community aquariums.
    • You prefer bold black and silver contrast.
    • You want a straightforward species for a newer aquarist.
    • You have enough room for a proper group.

    ❌ Avoid if:

    • You intend to keep only one or two individuals.
    • Your aquarium is too small for an active school.
    • You keep very slow-moving or delicate long-finned fish.
    • You want a solitary centrepiece species.

    Why choose Black Widow Tetras?

    Black Widow Tetras are long-established favourites because they combine strong visual contrast with hardy, adaptable behaviour.

    Their deep silver-grey body is marked by distinctive dark vertical bands, while the dorsal and anal fins can develop rich black colouration that looks especially striking in a planted aquarium.

    They are active schooling fish and become much more confident when kept in a proper group.

    The species is also forgiving of a reasonably broad range of water conditions once established, making it a reliable choice for community aquariums.

    Benefits

    • Hardy and beginner friendly
    • Distinctive black and silver colouration
    • Active schooling behaviour
    • Generally peaceful temperament
    • Easy to feed
    • Adaptable once established
    • Excellent for planted community aquariums

    Care made simple

    • Temperature: Approximately 20–26°C
    • pH: Approximately 6.0–7.5
    • Water: Clean, stable and well oxygenated
    • Diet: Omnivorous
    • Staple foods: Quality flakes and appropriately sized pellets
    • Supplement with: Brine shrimp, daphnia and bloodworms
    • Flow: Gentle to moderate
    • Setup: Plants around the sides and rear with open swimming space
    • Regular water changes help maintain strong colour and condition.
    • Keep in a proper social group.

    Pairs perfectly with

    • Other peaceful tetras
    • Rasboras
    • Corydoras
    • Small peaceful loaches
    • Gouramis
    • Other peaceful community fish of a similar size
    NTA Insight:
    Black Widow Tetras are much better fish in a group than they are as single specimens. Six should be treated as a practical minimum, while a larger group gives you more natural schooling, better confidence and less chance of one fish repeatedly bothering the same tank mate.

    FAQ

    What is the scientific name of the Black Widow Tetra?

    The accepted scientific name is Gymnocorymbus ternetzi.

    Is the Black Widow Tetra the same as the Black Skirt Tetra?

    Yes. Black Widow Tetra and Black Skirt Tetra are common names used for Gymnocorymbus ternetzi.

    How large do Black Widow Tetras grow?

    Adults generally reach approximately 5–6 cm.

    How many should I keep?

    Keep at least six, with larger groups preferred where aquarium size allows.

    Are Black Widow Tetras peaceful?

    They are generally peaceful community fish when kept in a proper group, although normal chasing and social sparring can occur.

    Do Black Widow Tetras nip fins?

    They can occasionally nip slow-moving or long-finned tank mates, particularly when kept in groups that are too small. A proper school helps direct their social behaviour toward one another.

    What should I feed them?

    Offer quality flakes or small pellets as a staple and supplement with live or frozen foods such as brine shrimp, daphnia and bloodworms.

    Can Black Widow Tetras live with shrimp?

    Adult shrimp may coexist with them in a well-planted aquarium, but small shrimp and shrimplets should be considered potential food.

    Do Black Widow Tetras need a heater?

    A heater is usually recommended where room temperature is not consistently within their preferred range.

    Can Black Widow Tetras breed in aquariums?

    Yes. They are egg-scattering fish and provide no parental care, so adults may eat eggs and fry unless a dedicated breeding setup is used.

    Are Black Widow Tetras suitable for beginners?

    Yes. Their hardiness, straightforward feeding requirements and adaptable nature make them a good beginner community fish once the aquarium is properly cycled.

    How long do Black Widow Tetras live?

    With clean water, good nutrition and appropriate social conditions, they commonly live for around 3–5 years and sometimes longer.

    Live Arrival & Ordering FAQ

    Why do livestock prices sometimes change?

    Unlike manufactured products, fish and shrimp continue to grow and develop over time. Their value changes as they increase in size, develop colour, or become breeding pairs.

    Our prices are based on the current size, quality and availability of each specimen. While pricing often remains stable for around 3–4 months, it may be updated at any time to reflect these changes.

    We always aim to offer healthy, high-quality livestock at fair and competitive prices.

    Do you offer a live arrival guarantee?

    Yes. All livestock is covered by our Live Arrival Guarantee.

    In the rare event of DOA, please contact us promptly with clear photos of the livestock in the original unopened bag.

    Please review our full DOA and store policies before purchase.

    Can you ship to all states in Australia?

    No. Due to state restrictions, we cannot ship livestock or live plants to WA and TAS.

    What should I check before ordering?

    Before placing an order, make sure:

    • Your tank is fully cycled and stable
    • Your aquarium has enough space for the species
    • Your current livestock are compatible in temperament, size, and requirements
    • Your water parameters, habitat, and temperature suit the species
    • You are not adding too many fish at once
    What should I expect when my fish arrives?

    It is normal for fish, shrimp, or snails to look pale, stressed, or less active after shipping.

    This is temporary. Most livestock will settle and regain colour within a few days.

    How long does it take for fish to settle in?

    Most livestock will take 3–7 days to fully adjust to their new environment.

    Should I feed my fish immediately after arrival?

    No. We recommend waiting 24 hours before feeding to allow them to settle.

    If you already have fish in your tank, feeding them before introducing new arrivals can help reduce stress.

    Why do fish sometimes struggle after being added to a tank?

    In most cases, issues are caused by tank conditions, not shipping.

    • Uncycled or unstable tanks
    • Poor water parameters
    • Overstocking
    • Unsuitable tank mates
    What is Nano Tanks Australia’s main tip for new livestock?

    Most livestock losses happen in immature or unstable tanks, not during shipping.

    If your setup is not fully established, the risk to new arrivals is significantly higher.

    Not sure if this fish is right for your setup?

    If you are unsure whether this species suits your setup, contact us before ordering and we’ll help point you in the right direction.

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