Cory Catfish (Corydoras) - UK

If you are searching for a lively, reliable community fish that adds contrast and movement without demanding specialist care, the Black Widow Tetra, Gymnocorymbus ternetzi, is a standout choice. Although this page targets the popular Cory Catfish search term, many aquarists actually keep Black Widow Tetras alongside bottom-dwelling Bronze Cory Catfish Corydoras Aeneus and Sterbai Cory Corydoras Tropical Fish Catfish because the combination works so well in peaceful tropical aquariums. Black Widows come from South America, usually reach around 6 cm, live for about 5 years with good care, and are widely considered one of the best schooling tetras for mixed tanks. Their smoky black fins, silver-grey body, and confident midwater swimming make them a dramatic contrast to the gentle foraging behaviour of corydoras on the substrate below.

See our detailed photos showing body shape, finnage, and the bold dark skirt that gives this species its common name. For fishkeepers comparing cory catfish size, cory catfish lifespan, and community suitability, Black Widow Tetras are often chosen as upper-level companions because they share similar water chemistry and appreciate a planted, well-filtered setup. If you have been researching the Black Widow Tetra: A Dramatic and Hardy Aquarium Star Scientific Name: Gymnocorymbus ternetzi, wondering about black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi tank size, black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi temperature, or the best black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi tank mates, this guide covers practical care in detail so you can build a thriving tropical community with confidence.

Where Do Black Widow Tetras Come From? Natural Habitat Explained

The black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi habitat is found in South America, especially within the Paraguay and Guaporé river basins. These waters are typically slow-moving to moderately flowing, with submerged roots, marginal vegetation, leaf litter, and shaded areas that soften the light. In the wild, this species spends much of its time in the middle water column, moving in loose groups and feeding on small invertebrates, plant matter, and organic particles drifting in the current.

For aquarists who also ask where do corydoras catfish come from, where are corydoras native to, and where do corydoras live, the answer is similar in a broad sense: many corydoras also come from South American freshwater systems. That is one reason Black Widow Tetras and corys are such a natural pairing in aquariums. If you keep Adolfo'S Cory Corydoras Adolfoi Hardy Aquaruom, Little Cory Corydoras Nanus Light-Spot Catfish, or X Black Cory Corydoras Tropical Fish, you can often recreate a convincing South American community by matching soft décor, open swimming space, and stable tropical temperatures.

In nature, the water is not always crystal clear. Tannins from wood and leaf litter can tint it slightly, and dense bankside growth creates dappled light. This matters because fish raised in aquariums still show stronger colour and calmer behaviour when their environment includes cover. Aquarists researching corydoras in the wild, corydoras natural habitat, where do corydoras like to hide, or even where do corydoras lay eggs are often trying to understand how natural behaviour translates into tank design. The same principle applies here: mimic the habitat, and you get better feeding response, stronger schooling, and less stress.

Black Widow Tetras are not pond fish in the UK climate, so unlike searches such as pygmy cory catfish in pond, they should be kept indoors in heated aquariums year-round. Their native habitat is tropical, not temperate. While odd search phrases like cory 36 lakeville may appear online, the important takeaway for fishkeepers is simple: recreate a warm, planted South American setting and these tetras settle quickly.

How to Set Up the Perfect Tank for Black Widow Tetras

A proper black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi tank setup starts with understanding that this is an active midwater schooling fish, not a solitary ornament. The official black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi minimum tank size is 60 litres, but that is really the floor, not the ideal. A group of 6 can live in a 60-litre aquarium, yet a 75-90 litre tank gives noticeably better swimming room and helps spread any mild fin-nipping within the group rather than onto tank mates. If you are comparing this with corydoras catfish tank size, corydoras tank size, panda cory catfish tank size, or pygmy cory catfish tank size, remember that tetras need horizontal swimming space while corys need floor area.

Tank Size Requirements

For a peaceful community, aim for 75 litres or more. This becomes even more important if you want a proper black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi schooling group of 8-10 fish. Larger groups tend to show more natural behaviour and less harassment toward slower tank mates. Aquarists who ask about dwarf cory catfish tank size, may pygmy cory catfish tank size, pygmy cory catfish minimum tank size, or panda cory catfish minimum tank size are usually balancing footprint and stocking level; the same logic applies here.

Water Parameters

The recommended black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi water temperature range is 22-28°C, with 24-26°C being a sweet spot for long-term community care. The ideal black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi pH requirements sit between 6.0 and 7.5, and hardness between 5 and 20 dGH. These fish are adaptable, but sudden swings are far more dangerous than a stable reading slightly outside the midpoint. If you are also checking panda cory catfish temperature, panda cory fish temperature, panda cory catfish tank temperature, what temp do panda cory catfish like, or pygmy cory catfish temperature, there is useful overlap for mixed community tanks.

Filtration

Use a reliable filter that turns the tank over around 5-8 times per hour without creating a blasting current. Black Widows appreciate oxygen-rich water but not a torrent. A mature sponge or internal filter works well in smaller tanks, while larger community setups benefit from a compact external filter. Keep the outflow aimed to create surface movement rather than a direct jet through the school.

Substrate

Because these fish occupy the middle region, substrate choice is more about the whole community than the tetra alone. If you are keeping them with corys, choose smooth sand or fine rounded gravel to protect barbels. This is especially important for keepers of Albino Golden Corydora Neon Cory Catfish or Red Neon Bronze Cory Corydoras Aeneus, which spend constant time sifting the bottom.

Plants & Decor

Dense side and rear planting with open central swimming space is ideal. Java fern, Amazon swords, Cryptocoryne, Limnophila, and floating plants all work well. Add driftwood and a few shaded zones to create black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi hiding spots. This species is excellent black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi for planted aquarium displays because the dark finnage contrasts beautifully with green foliage.

Lighting

Moderate lighting is best. Very bright light without cover can make them skittish. A 7-9 hour photoperiod suits most community tanks. Floating plants can soften the light and help fish display more natural black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi behaviour.

What Do Black Widow Tetras Eat? Complete Feeding Guide

The black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi diet is straightforward: they are omnivores and accept most quality aquarium foods. In the wild they pick at insect larvae, tiny crustaceans, plant fragments, and suspended organic matter. In captivity, the best black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi feeding guide combines a dependable staple with regular protein-rich extras.

Staple Foods

Use a high-quality tropical flake or micro-pellet as the base diet. Feed only what the group can consume in 30-60 seconds, once or twice daily. Despite online myths, they are not a true black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi bottom feeder, black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi algae eater, or black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi tank cleaner. They will pick at sinking items, but they should not be expected to live on leftovers.

Supplemental Foods

For better colour and condition, offer frozen or live daphnia, bloodworm, mosquito larvae, and brine shrimp 2-3 times per week. This is especially useful when conditioning fish for black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi breeding. Variety also helps if you keep mixed communities with corys and are comparing questions such as what do panda cory catfish eat, what do panda cory fish eat, what to feed panda cory catfish, what do pygmy cory catfish eat, what do pygmy cory fish eat, or what to feed pygmy cory catfish.

Feeding Frequency & Timing

Most groups do well with two small feeds daily. Searches like what time pygmy cory catfish eat, what time pygmy cory catfish can eat, what time pygmy cory catfish need to eat, when pygmy cory catfish eat, what day pygmy cory catfish eat, and what day pygmy cory catfish eat food reflect a common worry: timing matters less than consistency and making sure shy fish get a share. Feed Black Widows at roughly the same times each day, and if corys are in the same tank, add sinking foods after lights dim slightly so bottom fish are not outcompeted.

Foods to Avoid

Avoid fatty mammal meats, stale foods, and excessive freeze-dried-only diets. Also avoid assuming corys or tetras will control pest snails; searches such as what corydoras eat snails and which corydoras eat snails are usually answered with “very few, and not reliably.” If a fish stops feeding, check water quality first. The question why pygmy cory catfish not eating often points to stress, transport shock, or poor oxygen levels rather than food preference.

Time	Food	Amount
Morning	Quality tropical flake or micro-pellet	Small pinch, eaten within 1 minute
Evening	Frozen daphnia, brine shrimp, or fine granules	Small portion, no leftovers after 2 minutes

What Does the Black Widow Tetra Look Like? Colors, Patterns & Varieties

The classic Black Widow Tetra has a tall, laterally compressed body with a silver-grey base colour and distinctive dark vertical barring behind the gill area. The dorsal, anal, and pelvic fins deepen into smoky charcoal or black, creating the “widow” look that stands out in planted aquariums. The average black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi size is around 5-6 cm, making it large enough to be visible in a community tank but still suitable for modest aquarium sizes.

Females are usually slightly deeper-bodied and fuller when mature, while males tend to look slimmer. Younger fish often show sharper contrast, and adults in good condition develop a rich velvety black in the fins when kept over dark décor. Our photos show the best contrast achieved through stable water quality, moderate lighting, and a proper group size.

Some keepers compare them with cory species when planning a display and ask about corydoras duplicareus size, cory catfish types, or whether a certain catfish will visually balance the tank. Black Widows pair especially well with patterned bottom fish such as Gold Laser Cory Corydoras CW010 or the spotted look of corydoras julii-type fish. If you have seen searches like buy black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi UK, black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi for sale UK, black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi price UK, order black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi online UK, or live black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi for sale UK, appearance is one of the main reasons hobbyists choose them: few easy tetras offer such strong contrast.

What Fish Can Live With Black Widow Tetras? Compatibility Guide

Black Widow Tetras are usually peaceful, but they are active and can nip long flowing fins if kept in too small a group or cramped conditions. That is why the best best black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi for community tank setup includes at least 6 fish, with 8-10 even better. A proper black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi group size spreads social energy and makes them a far more peaceful black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi for aquarium choice.

Ideal Tank Mates

Excellent companions include rasboras, other medium tetras, peaceful rainbowfish, and many corydoras. If you are asking what corydoras can live together, what corydoras school together, or are corydoras schooling fish, the safest answer is to keep each cory species in its own group of 6 or more where possible, then combine that group with a midwater school like Black Widows. Good options include Bronze Cory Catfish Corydoras Aeneus, Sterbai Cory Corydoras Tropical Fish Catfish, Gold Laser Cory Corydoras CW010, Little Cory Corydoras Nanus Light-Spot Catfish, and Adolfo'S Cory Corydoras Adolfoi Hardy Aquaruom. These are classic examples of peaceful catfish UK hobbyists look for when building a South American community.

Species to Avoid

Avoid fancy guppies, male bettas with long fins, and slow ornamental fish unless the tank is large and heavily planted. Queries such as can corydoras live with bettas, can panda cory catfish live with betta fish, and can panda cory catfish live with bettas are about corys rather than tetras, but the same caution applies: the betta may be fine with bottom catfish yet stressed by active midwater tetras. Also avoid large cichlids; can corydoras live with cichlids is usually only true for carefully chosen dwarf species, not aggressive predators.

Community Tank Examples

In a 75-litre tank, try 8 Black Widow Tetras with 6 Bronze Corys. In a 90-litre setup, 10 Black Widows with 8 Sterbai Corys and a few snails works well. In a planted 120-litre aquarium, you can combine Black Widows, a cory group, and a small upper-level shoal. If you are wondering about 2 corydoras, that is not enough for proper social behaviour; corys should be kept in groups.

Compatibility with Shrimp and Goldfish

Adult shrimp may coexist in dense planting, but baby shrimp can be eaten. So for questions like are corydoras safe with shrimp and can corydoras live with shrimp, the answer is “usually with adult shrimp, less so with shrimplets.” Black Widows may also eat tiny shrimp if the opportunity arises. Goldfish are not suitable companions because of temperature and waste differences. That also answers can corydoras live with goldfish and can panda cory catfish live with goldfish: generally no.

For temperament questions, are cory catfish aggressive, are panda cory catfish aggressive, and are pygmy cory catfish aggressive are all usually answered with no. Corys are among the gentlest community fish. Likewise, can pygmy cory catfish live together and can pygmy cory catfish live with other fish are yes, provided tank mates are peaceful and not too boisterous.

Species	Compatible?	Notes
Sterbai Cory Corydoras Tropical Fish Catfish	✅ Yes	Excellent bottom-dwelling companion with similar tropical requirements.
Bronze Cory Catfish Corydoras Aeneus	✅ Yes	Hardy, active, and a strong match for community aquariums.
Long-finned bettas or fancy guppies	⚠️ Caution	May trigger fin-nipping, especially if tetra group is too small.
Large aggressive cichlids	❌ Avoid	Stress, predation risk, and incompatible behaviour.

How Do You Breed Black Widow Tetras? Complete Breeding Guide

Black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi breeding is considered easier than many tetras, though raising fry still takes planning. Mature females look rounder, especially when full of eggs, while males are slimmer. Condition adults with varied foods for 1-2 weeks before attempting to spawn them.

Breeding Setup

Use a separate 25-40 litre breeding tank with soft, slightly acidic water and fine-leaved plants or spawning mops. Keep lighting dim. A temperature around 26°C often helps. This section also answers broader searches like breeding cory catfish, cory catfish breeding, how to breed panda cory catfish, and pygmy cory catfish breeding in one important way: whether you breed tetras or corys, a dedicated spawning setup gives much better survival than a busy community tank.

Spawning Behaviour

Well-conditioned Black Widows scatter adhesive eggs among plants. Adults may eat eggs, so remove them after spawning. Aquarists asking when can corydoras breed, when do corydoras breed, when do corydoras spawn, when do corydoras lay eggs, or when do corydoras start breeding are usually looking for triggers; with Black Widows, frequent water changes and rich feeding are common cues.

Egg Care & Fry

Eggs usually hatch in about 24-36 hours depending on temperature, and fry become free-swimming a few days later. Start with infusoria or liquid fry food, then move to newly hatched brine shrimp. This is similar to many discussions around cory catfish eggs, cory catfish fry, and corydoras fry growth rate: tiny first foods and clean water are critical.

For people researching corys specifically, common questions include what do panda cory catfish eggs look like, what day pygmy cory catfish have babies, when pygmy cory catfish have babies, corydoras habrosus breeding, and pygmy cory cat breeding. Corys lay eggs rather than giving birth, and so do Black Widows. The exact timing varies with conditioning, age, and water changes. Also, what corydoras can cross breed is a separate concern for cory keepers; Black Widow Tetras are not part of that issue because they are a different genus entirely.

Black Widow Tetra vs Cory Catfish and Similar Community Fish: Which Should You Choose?

Shoppers often compare these fish because they serve different but complementary roles. If you searched for cory catfish for sale, corydoras catfish for sale, corydoras fish for sale, or buy panda cory catfish, you may still be deciding whether your tank needs a bottom shoal, a midwater school, or both. The simplest answer is this: Black Widow Tetras provide movement and contrast in the middle of the tank, while corys provide constant activity at the bottom.

Feature	Black Widow Tetra	Bronze Cory
Max Size	6 cm	6-7 cm
Care Level	Easy	Easy to moderate
Temperature	22-28°C	22-28°C
Price	£10.65	Varies by strain
Best For	Midwater schooling display	Bottom-dwelling community activity

Feature	Black Widow Tetra	Panda Cory
Max Size	6 cm	4.5-5 cm
Care Level	Easy	Moderate
Temperature	22-28°C	22-25°C preferred
Price	£10.65	Usually slightly higher
Best For	Active schooling contrast	Smaller peaceful bottom group

If you want a fish that is especially visible from across the room, choose Black Widows. If you enjoy subtle, constant substrate activity, choose corys. In larger tanks, keep both. This is often the best answer for hobbyists comparing corydoras panda, bronze corydoras, corydoras paleatus, sterbas corydoras, or even asking which pygmy cory catfish is best, which pygmy cory catfish should i buy, which pygmy cory catfish should i get, which pygmy cory catfish, or which pygmy cory catfish for sale. The right choice depends on tank footprint, temperature, and whether you want midwater or bottom-level behaviour.

Common Health Problems in Black Widow Tetras & How to Prevent Them

Strong black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi health starts with clean, stable water and a proper group size. Healthy fish swim confidently in the middle of the tank, feed eagerly, and show smooth finnage without clamped fins or white spots. Their dark fin colour should look even rather than patchy, and the body should be neither hollow-bellied nor bloated.

Common Diseases & Symptoms

The main black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi diseases seen in home aquariums are ich, fin damage from stress or nipping, and bacterial infections secondary to poor water quality. Like many tropical fish, they can develop white spot after transport stress or sudden temperature changes. Cory keepers often ask can corydoras get ich; yes, they can, and so can Black Widows.

Treatment & Prevention

Prevention is better than treatment. Keep ammonia and nitrite at zero, nitrate low, and avoid abrupt changes. Quarantine all new fish. Feed varied foods and do regular weekly water changes of 25-30%. If you keep corys in the same aquarium, choose medications carefully because some catfish are sensitive to harsh treatments. Also remember that searches like can corydoras live with cichlids often arise after stress-related disease in mixed tanks; unsuitable tank mates are a hidden health problem.

What Is Black Widow Tetra Behaviour Like in the Aquarium?

The typical black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi behaviour is active, social, and alert. They spend most of the day cruising the middle of the tank, especially in a visible black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi schooling group. They are not shy once settled, but they do appreciate cover and can become jumpy in bare, brightly lit tanks.

These fish are ideal black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi for beginners because their needs are simple and their behaviour is easy to read. If the group is too small, they may become pushy or fin-nippy. If the tank is too cold or water quality slips, they lose confidence and colour. In a balanced setup, they show a loose shoaling pattern with occasional bursts of synchronized swimming.

They also work well as black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi with other fish provided companions are peaceful and not long-finned. Their ideal black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi group size is 6+, though 8-10 is better. This social structure is one reason they combine so well with cory groups at the bottom, creating activity across the full tank.

Why Buy Black Widow Tetras from Tropical Fish Co?

When buying active schooling fish, consistency matters more than hype. Black Widow Tetras should arrive with intact fins, strong swimming posture, and a clear feeding response. We select batches for even size and community suitability so your new group settles faster and shows more natural schooling from day one. That matters whether you are searching black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi buy online UK, where to buy black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi UK, black widow tetra: a dramatic and hardy aquarium star scientific name: gymnocorymbus ternetzi shop UK, or simply comparing corydoras catfish price and tetra value for a community setup.

Before dispatch, fish are observed for condition, feeding, and transport readiness. They are packed in insulated boxes with appropriate bagging, and heat packs are used in cold weather. Tracked transport helps reduce delays, which is especially important for live fish. If you are comparing options like live catfish delivery UK, buy pygmy cory catfish, dwarf cory catfish for sale, could pygmy cory catfish for sale, or has pygmy cory catfish for sale, the same principle applies: healthy fish and careful packing are worth more than a vague low price.

We also support sensible stocking decisions. If your tank is better suited to corys first, we will say so. If your aquarium needs a midwater school to complete the layout, Black Widows are one of the strongest choices because they are hardy, visible, and adaptable. Order your Black Widow Tetras today with confidence and build a balanced tropical display with movement at every level.

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Complete your South American community with a bottom group such as Bronze Cory Catfish Corydoras Aeneus, a striking patterned option like Sterbai Cory Corydoras Tropical Fish Catfish, or a brighter contrast fish such as Gold Laser Cory Corydoras CW010. For smaller peaceful setups, Little Cory Corydoras Nanus Light-Spot Catfish is a smart choice. If you prefer unusual tones on the substrate, consider X Black Cory Corydoras Tropical Fish or Albino Golden Corydora Neon Cory Catfish. These species pair naturally with Black Widow Tetras in planted tropical aquariums and help create activity from top to bottom.