Easy
Ember Tetra (Hyphessobrycon amandae)
24–28°C · pH 5.5–7 · 30L
£3.99
Add cool metallic colour to your community aquarium with 6 Cochus Blue Tetra (Boehlkea fredcochui). A peaceful, active South American shoaling fish that reaches about 5 cm and thrives in established planted tropical tanks. Order now for UK delivery.
Adult size is the maximum length this species reaches at full maturity (scientific sources). The livestock you receive will be younger and smaller — pick a size variant above for the actual shipping size. Photos are AI-enhanced, so the animal may show subtle colour or marking differences.
Boehlkea fredcochui
Cochus Blue Tetra are a shoaling species — they need 6+ to feel safe and show their full colour.
Add cool metallic colour to your community aquarium with 6 Cochus Blue Tetra (Boehlkea fredcochui). A peaceful, active South American shoaling fish that reaches about 5 cm and thrives in established planted tropical tanks. Order now for UK delivery.
Adult size is the maximum length this species reaches at full maturity (scientific sources). The livestock you receive will be younger and smaller — pick a size variant above for the actual shipping size. Photos are AI-enhanced, so the animal may show subtle colour or marking differences.
Maintain these water conditions for optimal health and vibrant colors
The Cochus Blue Tetra, Boehlkea fredcochui, is one of those fish that looks understated in a shop tank and then becomes extraordinary once settled into a planted aquarium. This slim South American characin develops a cool metallic blue sheen that flashes across the middle of the tank, especially when kept as a cochus blue tetra school of 6 or more. Native to the Amazon Basin in Peru, it is a peaceful, active shoaler with an adult size of around 5 cm, a blue tetra lifespan of roughly 5 years, and an easy care level that suits many mixed tropical aquariums. For aquarists planning a blue tetra tank setup, this species stands out because it combines hardy tetra behaviour with a more unusual colour than many common community fish UK staples. It is often chosen as a colourful tetra for planted tank layouts, and it also works well as a blue tetra for planted aquarium display where dark substrate and greenery help the body colour glow. See our detailed photos showing the reflective body tone, streamlined profile, and natural schooling posture in the water column. If you want a vibrant blue schooling fish UK hobbyists can keep without the demands of delicate wild specialists, the Cochus Blue Tetra is a smart, rewarding choice.
Boehlkea fredcochui belongs to the broad characid family that includes many of the hobby's best-known South American shoaling fish. In the trade it may be called Cochus Blue Tetra, blue king tetra, or simply a blue tetra. Its appeal comes from its active midwater schooling, durable nature, and unusual steel-blue body colour, which gives a different look from the red-and-silver tetras most keepers already own.
The Cochus Blue Tetra is a true Amazon characin. Its home is the Amazon Basin of Peru, where it inhabits warm, slow to moderately flowing waters with leaf litter, submerged roots, and scattered aquatic vegetation. In this tetra fish habitat, the fish move in loose groups through the middle layers, feeding on tiny invertebrates, insect larvae, plant matter, and organic particles suspended in the water. Understanding how a tetra fish in the wild actually lives makes it much easier to keep this species in strong colour and condition at home.
Soft to moderately hard water, subdued lighting, dark decor, and open swimming lanes all encourage natural confidence. A warm Amazon-inspired aquarium with driftwood, fine substrate, and floating plants mimics the dappled light of its natural waters. In these conditions, Cochus Blue Tetras show more stable colour and tighter shoaling than they do in sparse, brightly lit, bare setups. The fish spend much of their time cruising the middle region, darting together when startled and spreading out again once relaxed.
As for diet in nature, this species is an opportunistic micro-predator and omnivore, taking tiny live prey and biofilm-associated foods. That is why it responds so well to a varied captive menu rather than one dry flake alone. In short, if you build your tank around a realistic South American stream theme, you will get healthier fish and better colour.
Mimicking a natural Amazon-style habitat with dark substrate, wood, and broken lines of sight reduces stress and brings out a stronger blue reflection. Fish kept in mature, planted tanks almost always colour up better than fish kept in bright, open decor.
A successful blue tetra tank setup starts with space for movement. Although these fish are small, they are energetic midwater swimmers, so the blue tetra tank size should not be judged by body length alone. The practical minimum is 80 litres, which also suits the recommended blue tetra minimum school size of 6 or more. For a more natural display and calmer group dynamics, a longer aquarium of 90 cm or more is even better. When planning a tetra fish tank setup or tetra fish aquarium setup for this species, think in terms of horizontal swimming room rather than just litres.
For this listing of six fish, the minimum recommended volume is 80 litres, but 100-125 litres gives noticeably better schooling behaviour. Cochus Blue Tetras are active and appreciate extra length, so a roomy tank is a real advantage and is the single biggest factor in how settled the shoal looks. If you are planning a mixed shoal with species like Glowlight Tetras or Diamond Tetras, size up rather than down.
The ideal blue tetra temperature is 24-26°C, though the safe blue tetra temperature range is 23-28°C. If you need a single target, aim for 25°C for a stable community setup. The tetra fish aquarium temperature should not swing sharply between day and night. pH can sit between 6.0 and 7.5, and hardness between 3 and 15 dGH, making this a forgiving species for many UK tropical setups.
A gentle but effective filter is best. You want enough turnover to keep oxygen levels high and waste low, but not so much current that the shoal is forced to fight the flow all day. Sponge filters, internal filters with spray bars, or well-baffled externals all work. In planted tanks, steady filtration helps maintain the stable conditions that meet the everyday tetra fish requirements of this species.
Dark sand or fine gravel makes the blue body tone look richer. This is one of the simplest ways to improve appearance in a blue tetra for planted aquarium. Add driftwood, branches, and clumps of easy plants to create shelter around the edges while leaving open water in the centre. Good companions for this style include Emperor Tetras and Bleeding Heart Tetra in larger aquariums. If you want a true South American visual, combine dark decor with stem plants and floating cover.
Moderate lighting works best. Very bright light can wash fish out unless balanced by floating plants or tannin-stained decor. A 6-8 hour photoperiod is usually enough for fish comfort and plant health. This matters most if you are upgrading from a basic setup to a more display-focused aquascape built around the colour of the shoal.
Always cycle the aquarium for 4-6 weeks before adding your shoal. Stable biological filtration matters more than chasing an exact pH number, and it is one of the biggest differences between fish that merely survive and fish that thrive.
The ideal blue tetra diet is varied, light, and frequent rather than heavy and occasional. These fish are omnivores, so their tetra fish diet should include quality flakes, micro pellets, and regular frozen or live foods. The simplest rule for what to feed tetra fish of this size is to choose small foods that stay suspended in the water column long enough for the whole shoal to take them comfortably.
A fine tropical flake or micro pellet should form the base of the diet. Good tetra fish flakes remain a practical everyday option, so choose a high-quality staple with fish meal, crustacean content, and added vitamins. Avoid relying on foods formulated for other fish, such as goldfish flakes, long term, because they are balanced for different nutritional needs.
For stronger colour and condition, add frozen daphnia, cyclops, baby brine shrimp, and finely chopped bloodworm 2-4 times per week. This mirrors the small-invertebrate element of the species' wild diet and supports a more complete tetras diet. If you are preparing fish for spawning, this richer style of blue tetra feeding is especially useful.
The best routine for when to feed tetra fish is twice daily in small portions. Offer only what the shoal can finish in around 30-60 seconds. Smaller, more frequent meals also help if a new or shy fish is slow to start eating, because nervous fish often do better than they would with one large dump of food.
| Time | Food | Amount |
|---|---|---|
| Morning | Fine flake or micro pellet | Small pinch, eaten within 1 minute |
| Evening | Frozen daphnia, cyclops, or baby brine shrimp | Very small portion |
Overfeeding causes ammonia spikes, cloudy water, and sluggish fish. Cochus Blue Tetras are eager feeders, so it is easy to give too much. A lean, varied diet keeps colour sharper and reduces digestive stress.
The appeal of this species is all in the sheen. This fish shows a cool metallic blue to blue-silver body tone with a subtle violet cast under the right light, which is why some aquarists loosely group it with purple freshwater aquarium fish in certain planted displays. The body is slim and laterally compressed, with clear fins and a fast, elegant swimming style.
The average cochus blue tetra size is about 5 cm, and keepers searching blue king tetra size will find it sits in the small-to-medium tetra range. It is larger and more streamlined than many nano tetras, yet still suitable for a peaceful community. Males are usually slimmer and may appear slightly more intensely coloured, while females are a little fuller-bodied, especially when carrying eggs. Telling male and female apart is far easier in mature groups than in young stock.
If you are building a display around contrast, this is one of the best blue tetra species for dark substrate and green planting. Good colour depends on diet, low stress, and stable water. If the fish ever start to fade, the usual causes are stress, poor water quality, a weak diet, or overly bright, exposed conditions. This cochus blue tetra care guide approach focuses on correcting those basics before blaming the fish.
A common question is whether the blue tetra is aggressive. In a proper group and a suitable tank, the answer is usually no. These are peaceful shoaling fish, but like many characins they can become restless or mildly nippy if kept in too small a number or in cramped quarters. A settled shoal in an 80 litre or larger aquarium is far calmer than a handful of tetras crammed into a small tank. They are not strongly territorial in the cichlid sense, though they may spar lightly within the group.
These are firmly schooling fish, so they do best in groups. Cochus Blue Tetras school most tightly with their own kind, but they can share a tank with other peaceful shoalers. This makes them a strong cochus blue tetra for community tank option and one of the more unusual schooling fish UK keepers can add to a planted display.
Good companions include similarly sized, peaceful South American fish. In larger aquariums, consider Glowlight Tetras, Diamond Tetras, Emperor Tetras, Bleeding Heart Tetra, and Congo Tetra. For a cooler blue-green contrast, Green Neon Tetras can work in a larger, well-structured community, though each species should still be kept in its own proper group.
Avoid large predatory fish, fin-nipping barbs, and slow long-finned species in cramped tanks. This species is not among the worst fin-nippers, but understocked groups can pick at trailing fins. Pairing it with bettas is therefore not a safe default; it can work in larger, heavily planted aquariums but is not guaranteed. Likewise, mixing small tetras with large, adult angelfish is risky, because adult angels may treat small tetras as prey.
Cochus Blue Tetras can live with guppies as long as water parameters suit both species and the guppies are not overly long-finned. For shrimp, the picture is mixed: adult Amano shrimp are usually fine, but small Neocaridina shrimplets may be eaten. Snails are generally safe. This species is therefore a cautious rather than perfect shrimp companion.
| Species | Compatible? | Notes |
|---|---|---|
| Glowlight Tetras | ✅ Yes | Similar size and peaceful temperament; ideal in planted community tanks |
| Emperor Tetras | ✅ Yes | Best in larger aquariums with open swimming space and visual breaks |
| Diamond Tetras | ⚠️ Caution | Fine in roomy tanks; avoid crowding as both species are active midwater swimmers |
| Bettas | ⚠️ Caution | Possible in some setups, but fin-nipping risk means not a first-choice pairing |
| Large Angelfish | ❌ Avoid | Adult angels may harass or prey on smaller tetras |
The broad rule for tank mates is peaceful fish of similar size and speed. This species is among the best blue tetra for community tank layouts because it is active without being domineering when kept correctly.
Always quarantine new arrivals for 2-4 weeks before adding them to a community aquarium. Many compatibility problems blamed on temperament are actually stress responses caused by disease introduction or unstable water after stocking.
Cochus blue tetra breeding is possible in captivity, but it is not usually the first tetra fish breeding project a beginner attempts. The species is an egg scatterer, and breeding difficulty is best described as moderate. The broad method follows the familiar tetra pattern: condition a healthy group, separate a pair or small breeding group, provide fine-leaved plants or spawning mops, and remove the adults after spawning.
Use a separate, dimly lit tank of 25-40 litres with soft, slightly acidic water and a temperature around 25-27°C. A sponge filter is ideal. Fine plants or mesh help protect the eggs from hungry adults. Condition the males and females on frozen foods for 1-2 weeks first.
During courtship the males become more active and the females appear fuller through the abdomen. Tetras do not become pregnant; instead the females become egg-laden, then scatter eggs among the plants. Look for a rounded female, increased chasing, and early-morning activity as signs that a spawn is near. Most spawning happens at first light.
Once eggs are laid, remove the adults. The eggs are small and vulnerable to fungus, especially in bright light or hard water. Hatching usually occurs within about 24-36 hours depending on temperature, and the fry become free-swimming a few days later. At that point, feed infusoria or liquid fry food, then move on to newly hatched brine shrimp. With soft water and careful conditioning, success is realistic, even though this species is a little less straightforward than the hardiest characins.
For better hatch rates, use very soft water and keep the breeding tank dim for the first few days after spawning. Many tetra eggs are light-sensitive, and reducing brightness can make a noticeable difference.
Blue characins are often confused in shops and in search results. Keepers compare the Cochus Blue Tetra with the blue king tetra (a trade name for the same fish), the green neon tetra, the diamond tetra, and other blue-toned shoalers. The key is to focus on behaviour, adult size, and the look you want in the aquarium rather than the marketing name on the tank.
| Feature | Cochus Blue Tetra | Green Neon Tetra |
|---|---|---|
| Max Size | 5 cm | 3.5-4 cm |
| Care Level | Easy | Easy to moderate |
| Temperature | 23-28°C | 22-26°C |
| Price | Varies by group size | Varies by stock line |
| Best For | Active midwater shoals in 80L+ tanks | Smaller peaceful planted communities |
| Feature | Cochus Blue Tetra | Diamond Tetra |
|---|---|---|
| Body Look | Cool metallic blue sheen | Sparkling silver with reflective scales |
| Temperament | Peaceful, active | Peaceful, slightly more robust |
| Tank Style | Best in open planted shoals | Best in mature planted community tanks |
| Best For | Keepers wanting a Peruvian blue tetra school | Keepers wanting glittering body texture |
| Alternative | Green Neon Tetras | Diamond Tetras (Moenkhausia pittieri) |
Choose the Cochus Blue Tetra if you want a fast, coordinated shoal with a steely blue flash rather than a red-and-blue stripe. It is a great option for aquarists who want something less common than standard community tetras but still manageable as a peaceful species. If your goal is a larger, shimmering centrepiece shoal, compare it with the Congo Tetra or with Blue Emperor Tetras.
Healthy Cochus Blue Tetras are alert, streamlined, eager to feed, and consistently active in the middle of the tank. Faded colour, clamped fins, isolation from the shoal, or refusal to eat are all early warning signs. As with all characins, the most important habits are simple: buy well, quarantine carefully, and never ignore wasting, spinal curvature, or patchy colour loss.
Most problems in tetras trace back to water quality, stress, and the introduction of unhealthy stock rather than to a single mystery illness. In a mixed community, any suspicious fish should be isolated quickly, because similar symptoms can overlap with bacterial infections, parasites, and severe stress. Keep water quality high with weekly maintenance, avoid sudden temperature drops below the tropical range, and feed a varied diet to support immunity. If fish stop feeding, revisit stocking, stress, and water chemistry first.
Never use medication blindly in a display tank. Remove carbon if treatment is required, confirm the diagnosis where possible, and remember that copper-based medications are dangerous around shrimp and other invertebrates.
Cochus Blue Tetras are lively, visible fish that spend most of their time in the middle layers. They are not shy once established, but they do settle faster when kept in a proper group and given cover around the tank edges. A small handful of tetras feels unnatural for a shoaling species; a proper cochus blue tetra school of 6 is the minimum, and larger groups look better and behave more calmly.
Their social structure is loose rather than rigid. They spread out while feeding, then tighten into a coordinated group when startled. This is why they make such effective schooling fish UK display fish in planted aquariums - active enough to hold attention without becoming chaotic. In a mature tank, you will often see them patrol open water, then dip into plants or driftwood shade before returning to the centre.
Colour can shift with mood and environment. If the fish look pale first thing in the morning or after transport, that is normal. Persistent fading suggests stress, poor diet, or unsuitable lighting. A stable group size, warm water, and a well-designed blue tetra tank setup are the best ways to encourage natural behaviour and stronger colour.
When you are looking for blue tetra for sale, quality matters more than a low headline number. Active shoaling fish like this need to arrive in strong condition, with full fins, good body weight, and stable colour recovery after transport. Our aim with every buy cochus blue tetra UK order is to supply fish that settle quickly into a community aquarium rather than fish that need weeks of recovery. This is especially important for species sold in groups, because one weak fish can unsettle the whole shoal.
Each cochus blue tetra for sale UK group is checked for body condition, swimming posture, and feeding response before dispatch. Fish are held, observed, and prepared for UK aquarium conditions so they transition more smoothly after arrival. For customers comparing blue tetra price UK, cochus blue tetra for sale online UK, buy blue tetra online UK, or buy Peruvian blue tetra UK, the real value is in healthy stock that starts feeding and schooling promptly.
Orders are packed in insulated boxes with professional fish bags, and heat packs are used in winter conditions when needed. Tracked delivery with a licensed live-animal courier helps reduce time in transit. Whether you have searched blue king tetra for sale, blue king tetra buy UK, or simply cochus blue tetra for sale, remember that species identity, group health, and packing standards matter as much as the label on the bag.
A care sheet and acclimation guidance help you settle your fish properly on arrival. Slow temperature equalisation, careful mixing of water, and lights-off introduction all reduce stress. Order your Cochus Blue Tetra shoal today with confidence if you want an unusual, peaceful South American tetra that adds movement and cool metallic colour to a planted community aquarium.
Build a richer South American display with species that complement the Cochus Blue Tetra's shape and swimming style. For warm colour contrast, try Glowlight Tetras. For more sparkle in mature planted tanks, add Diamond Tetras. If you want a regal shoaling companion in a larger aquarium, consider Emperor Tetras. For a bolder centrepiece tetra, explore the Congo Tetra. If you are comparing classic blue-toned shoalers, see the Green Neon Tetra. And if you want a more unusual blue-characin mix in a spacious setup, Blue Emperor Tetras are another excellent option.
24–28°C · pH 5.5–7 · 30L
18–28°C · pH 6–8 · 80L
22–28°C · pH 5.5–7.5 · 60L
23–28°C · pH 5.5–7.5 · 60L
23–27°C · pH 4.5–7 · 60L
23–28°C · pH 5.5–7.5 · 60L
18–26°C · pH 6.5–8 · 30L
23–27°C · pH 7.4–8.4 · 500L
20–27°C · pH 6–7 · 54L
23–27°C · pH 7.4–8.4 · 150L
24–28°C · pH 6.5–7.8 · 300L
20–24°C · pH 7–8 · 45L
24–28°C · pH 6.5–7.5 · 2000L
24–28°C · pH 7.5–8.5 · 200L
24–28°C · pH 5.5–7 · 60L
18–25°C · pH 6–8 · 100L
24–28°C · pH 7–8 · 120L
18–28°C · pH 6.5–8 · 20L
24–27°C · pH 7.5–8.8 · 150L
22–26°C · pH 6–7.5 · 60L
24–28°C · pH 7.5–8.5 · 40L
24–28°C · pH 7.5–8.5 · 500L