Emperor Tetra Black (Nematobrycon palmeri black)

Choose this peaceful American tetra for a settled community

Emperor Tetra Black (Nematobrycon palmeri) is a freshwater American tetra in the family Acestrorhamphidae. FishBase places its native range in South America’s Atrato and San Juan river basins and records a maximum length of 4.2 cm standard length. This lively, peaceful shoaling fish suits a keeper who can provide a mature filtered aquarium, a proper group and carefully screened community companions.

Keep the group at 23–27°C, pH 6.5–7.5 and 5–12 dGH. These routine values are the overlap of FishBase’s environmental range, the Seriously Fish aquarium guidance and OATA’s tetra and pencilfish guidance. OATA’s figures apply to the wider group, while the overlap keeps every value within the ranges recorded for this species.

Who will find it manageable

Our easy care label reflects its suitability for newcomers rather than permission to skip preparation. Seriously Fish calls it one of the best choices for newcomers to fishkeeping, but success still depends on a mature biological filter, weekly testing, controlled feeding and enough room for the shoal. Its small body does not remove the need for swimming length or social space.

This is a useful choice when you want a peaceful shoaling species rather than a solitary centrepiece. You can also browse the current tetra collection when comparing other identities and care requirements, but assess each species against the aquarium’s measured water, adult size and existing occupants.

Select the dispatch size and quantity you need

Use the live size selector to choose the label that fits your stocking plan: 1.5–2 cm, 2–3 cm or 3–4 cm. One purchase supplies one fish of the selected size, so set the purchase quantity to the number of fish required for the group. The size you select is the size supplied, not the adult size. Plan the permanent aquarium around the recorded 4.2 cm standard length and the space needed by the complete shoal.

Build the group deliberately

Keep at least six Emperor Tetras Black together, with ten or more preferred where aquarium capacity permits. For example, a new six-fish shoal requires a purchase quantity of six after you have chosen the size. If you already keep four compatible Emperor Tetras, two additional fish would bring the group to the stated minimum, but test the aquarium and consider its total biological load before increasing the population.

Sex is guaranteed only when the selected option explicitly states male or female. This Emperor Tetra Black listing has no sex-guaranteed option.

Read the gallery as a visual guide

The gallery images are representative, based on reference photographs of this species, so colours can look slightly different from the live animal.

The scenes show the listed identity in planted, plain-background and wood-based compositions. Use them as a general visual guide only, not to judge the sex of the fish that will be sent or the number included in one purchase. One gallery scene contains two fish, while the offer itself remains one live fish per purchase quantity.

Plan the aquarium around the adult size

Use an aquarium with a base of at least 90 × 30 cm, or an equivalent footprint, and about 81 litres. Seriously Fish describes that as the smallest aquarium that should be considered for Nematobrycon palmeri. FishBase separately gives a minimum aquarium length of 80 cm, so the 90 cm recommendation also clears that length threshold.

Prioritise length and usable group space

The footprint must accommodate a shoal of at least six as well as any other inhabitants. Treat 81 litres as a minimum planning point, not an assurance that every community combination will fit. More fish increase feeding and waste, and OATA advises increasing an aquarium population slowly so the biological filter can respond to the added load.

Size the equipment for the aquarium

At about 81 litres, Seriously Fish recommends filtration turnover of four to five times the aquarium volume per hour and gives a filter rating of 325–405 litres per hour. Holding 23–27°C in an aquarium of this size, in a room around 20°C, needs a heater of roughly 75–100 W. Match the final equipment to the actual aquarium volume and room conditions while keeping the stated temperature stable.

Check that décor does not remove the usable footprint needed by the group. Shelter and plants are valuable, but retain clear swimming room rather than filling every part of the base. Review the entire stocking plan whenever another shoal, bottom-dwelling group or territorial fish is proposed.

Mature the filter and furnish the aquarium before adding fish

Run a well-established biological filter and confirm that ammonia and nitrite are both zero before adding the shoal. The RSPCA’s aquarium welfare guidance explains that fish release toxic ammonia, while beneficial bacteria in a working biological filter convert it first to nitrite and then to the safer nitrate. A filter is therefore essential rather than optional equipment.

If this is your first aquarium, use our guide to prepare and mature a first tropical tank before choosing an arrival date. Maturation is complete only when testing shows the filter can process waste; elapsed time by itself is not the deciding measurement.

Create cover without losing swimming room

Use aquarium gravel or sand, then add live plants where practical. OATA recommends plants for cover and advises using suitable artificial plants and ornaments when live planting is not used. Arrange shelter around open swimming space so the fish can move as a group without being confined to narrow gaps.

• Filter: keep it running and maintained so its bacterial population can process ammonia and nitrite.
• Substrate: use aquarium gravel or sand.
• Cover: include plants or suitable ornaments that create shelter.
• Swimming space: preserve an open area for the shoal.
• Current: use the gentle current recommended by OATA for smaller tetra species.

Increase the population carefully

Beneficial bacteria must increase when more fish and food are added. Stocking too quickly can create new tank syndrome, in which the filter cannot process the rising waste and ammonia or nitrite reaches harmful levels. Plan the minimum Emperor Tetra group as part of the aquarium’s starting biological load, then delay additional community fish until test results remain stable.

A mature aquarium still needs regular attention. Filtration, appropriate stocking and measured feeding work together; none can compensate indefinitely for excessive waste or an aquarium that is too small for its inhabitants.

Hold the water inside the routine overlap

Keep Emperor Tetra Black at 23–27°C, pH 6.5–7.5 and 5–12 dGH. This range is the shared overlap of FishBase, Seriously Fish and OATA guidance, so every routine value remains inside the environmental and aquarium ranges attributed to this fish. Keep conditions stable rather than allowing the readings to move repeatedly between the extremes.

Use measurements to make the stocking decision

Test the aquarium before the fish are added and at least weekly afterwards. Our water chemistry guide explains what the principal readings mean, while the water matcher helps compare measured aquarium values with this range.

A pH reading of 7.2, for example, sits within the routine interval when temperature and hardness also align. A pH of 6.2 sits below the routine range of pH 6.5–7.5, so it does not count as a match. Apply the same complete check to temperature and hardness rather than approving a match from pH alone.

Respond to nitrogen waste first

Any detectable ammonia or nitrite requires attention because the target for both is zero. Review recent stocking and feeding, check the filter for blockages and carry out the maintenance described for this aquarium. Do not respond by feeding more or adding more fish while waste readings are elevated.

Record the results so gradual changes are visible. A stable sequence of readings is more useful than one isolated test because it shows whether the filter, feeding level and maintenance routine are working together.

Feed for the recorded natural diet

Base the diet on small foods that fit this fish’s recorded animal-based feeding. FishBase records worms and crustaceans, while Seriously Fish describes a likely micropredator taking small insects, worms, crustaceans and other zooplankton in nature. In the aquarium it accepts suitably sized dried foods, but these should not be the only food offered.

Feed once a day and offer only what the shoal can eat within a few minutes. That schedule and portion rule come from OATA’s guidance for tetras and pencilfish. Small live or frozen foods such as Daphnia, Artemia, small bloodworm or tubifex add the variety recommended across the care guidance.

Judge the portion by the whole shoal

Distribute the food so the group can feed within the stated time. If food remains after a few minutes, reduce the next portion rather than extending the feeding window. Uneaten food breaks down and adds toxic waste, so generous feeding can undermine water quality even when the food itself is appropriate.

Watch whether every fish approaches food. Reduced intake or a complete loss of interest is one of OATA’s warning signs. Test water quality if appetite changes, then compare swimming, breathing, colour and body condition with the fish’s normal pattern.

Do not turn conditioning foods into an extra meal. Variety should replace part of the daily portion, not sit on top of it. This keeps the diet aligned with the recorded feeding biology while limiting the waste placed on the filter.

Keep the weekly maintenance routine consistent

At least once every week, carry out a partial water change of 25%. Use a siphon where helpful to remove solid waste from the substrate.

Prepare replacement water safely

Treat replacement tap water with conditioner to remove harmful chlorine or chloramine before adding it to the aquarium. Keep the replacement water and aquarium within the planned conditions so routine maintenance does not push temperature, pH or hardness outside the stated range.

Protect the biological filter

Do not rinse filter media under the tap. Any chlorine or chloramine in tap water may kill the beneficial bacterial population established in the media. Lightly rinse it in removed aquarium water instead, which reduces the amount of bacteria lost during cleaning.

Cleaning should restore normal flow without stripping the filter unnecessarily. Check for blockages as part of routine maintenance, but preserve the bacterial population that processes the fish’s waste. Continue testing after maintenance so any change in filter performance is detected through the water readings.

Review the complete system

Use the weekly session to compare feeding, waste, group behaviour and test results. If nitrate rises more quickly than before, look for uneaten food, increased stocking or accumulated solid waste. If ammonia or nitrite appears, pause further stocking and address filtration and husbandry before adding animals.

Follow the arrival sequence before releasing the fish

Tropical Fish Co’s delivery and Live Arrival Guarantee policy explains the packing and arrival procedure. Fish are hand-bagged in pure oxygen and placed in an insulated poly box, with a heat pack when the weather calls for it. Someone must be at the address to receive the parcel because live fish cannot be left unattended.

Use this order when the parcel reaches you

1. Receive the parcel in person and start filming before opening it. Show the parcel still sealed with the outer box visible.
2. Open the parcel in one continuous take. Keep filming until the fish can be seen inside the sealed bag before anything is disturbed.
3. Inspect the fish on the day the parcel arrives. Retain the continuous video as the arrival record.
4. Float the bag for 20–30 minutes before releasing the fish. Let the bag float for the full 20–30 minutes so the fish acclimatise slowly.
5. Do not pour the bag water into the aquarium. Release the fish without adding transport water to the established system.

If a Live Arrival Guarantee claim is required, contact us on the same day with the order number and continuous unboxing video showing the sealed parcel, the opening and the fish inside the sealed bag.

Prepare the aquarium separately

Before the parcel arrives, follow OATA’s advice to confirm that ammonia and nitrite are zero and that the aquarium’s water values are suitable.

After release, maintain the normal once-daily feeding limit and watch each fish’s swimming, breathing and interest in food. Increase the wider aquarium population slowly because the biological filter must adjust whenever fish numbers and feeding increase.

Act on changes in health or behaviour early

Learn the group’s normal swimming, colour, breathing, feeding and use of cover, then act when a clear change appears. OATA advises watching for altered swimming, darker or paler colour, changed aggression or hiding, abnormal breathing, skin or fin damage, changes in body condition and reduced feeding.

Let the test results guide the first response

Water quality is the first practical check because ammonia and nitrite must remain at zero. Confirm temperature, pH and hardness as well, then check the filter for blockages and review whether feeding or stocking has recently increased.

Do not guess a diagnosis from one sign or begin an arbitrary medication routine. Different problems can alter swimming, breathing or appetite in similar ways. Record what changed, when it began and which fish are affected, then contact us for further guidance whenever a fish’s health concerns you.

Daily observation complements the weekly maintenance schedule. It does not require disturbing the aquarium; the purpose is to notice meaningful departures from normal behaviour early enough to check the system and respond.

Keep a large enough shoal for natural behaviour

Keep at least six Emperor Tetras Black together, and choose ten or more where the aquarium’s space and filtration allow it. Seriously Fish recommends at least half a dozen and preferably ten or more because this is a shoaling species that will fare much better in the company of its own kind. Plan for at least six rather than five, so the shoal meets the larger recommended group.

Count the group before adding companions

Reserve capacity for the Emperor Tetra shoal first. A community plan that leaves room for only four of these fish does not meet the stated minimum, even if the total fish count appears high. Correct the social-group plan before using remaining capacity for another tetra group, bottom dwellers or feature fish.

Expect lively but peaceful community behaviour

Seriously Fish describes this tetra as lively and peaceful and recommends it for a general community setup. Give the shoal enough swimming room, then observe how it shares space with existing inhabitants. A peaceful species description does not remove the need to watch actual interactions after stocking.

Group size must not be treated as a substitute for water quality. More fish also mean more feeding and waste, so maintain the same zero-ammonia and zero-nitrite targets and continue weekly tests after the group increases.

Screen every community companion before mixing fish

Choose peaceful companions of similar size and temperament that share the complete 23–27°C, pH 6.5–7.5 and 5–12 dGH routine range. Seriously Fish identifies several kinds that can be considered, but each proposed combination still needs enough space for every adult fish and complete social group.

Avoid predators

Avoid larger species that may see the Emperor Tetra as food. It is not safe with fish large enough to eat it. Do not treat heavy planting, feeding frequency or the size at dispatch as protection from an adult predator.

Use a repeatable screening rule

• Compare the adult size of every proposed companion.
• Choose peaceful fish of similar size and temperament, following OATA’s general mixing rule.
• Confirm that every species shares the complete routine water range.
• Reserve the required footprint and social-group space for all inhabitants.
• Observe interactions and act if persistent chasing, damaged fins, hiding or reduced feeding appears.

For fish outside the kinds named above, compatibility requires case-by-case assessment rather than a universal answer. Compare each one’s adult size, temperament, water range and space needs against this shoal before mixing.

Before adding shrimp, snails or other invertebrates, check the needs and risks of the exact animal against this fish’s diet of worms, crustaceans and other small animal foods.

Answer common Emperor Tetra questions

How big does Emperor Tetra Black get?

FishBase and Seriously Fish both record a maximum of 4.2 cm standard length for Nematobrycon palmeri. Plan the permanent aquarium around that adult figure rather than the fish’s dispatch size.

What size aquarium does this tetra need?

Emperor Tetra Black needs an aquarium with a base of at least 90 × 30 cm or equivalent and a volume of about 81 litres. Seriously Fish describes this as the smallest aquarium that should be considered.

How many Emperor Tetras Black should I keep together?

Keep at least six Emperor Tetras Black together, with ten or more preferred when the aquarium’s space and filtration permit it. Seriously Fish gives this species-specific shoaling recommendation.

Does this fish suit beginners?

Yes. Emperor Tetra Black is Nematobrycon palmeri, which Seriously Fish describes as one of the best choices for newcomers to fishkeeping; beginners still need a mature filter, an aquarium of about 81 litres with a 90 × 30 cm base, weekly testing and a group of at least six.

What should I feed Emperor Tetra Black?

Feed suitably sized dried animal-protein food with small live, frozen or freeze-dried foods such as Daphnia or Artemia for variety. Offer only what the shoal eats within a few minutes once a day.

What temperature, pH and hardness does it need?

Keep Emperor Tetra Black at 23–27°C, pH 6.5–7.5 and 5–12 dGH. These routine values are the overlap of FishBase, Seriously Fish and OATA’s tetra-group guidance.

Is it aggressive or likely to nip fins?

Seriously Fish describes it as lively and peaceful. Monitor interactions and separate fish if persistent chasing, damaged fins, hiding or reduced feeding appears.

Which fish can live with it?

Consider most commonly kept livebearers, danionins, rasboras, other tetras, Corydoras, smaller Loricariids, and most commonly kept gouramis or dwarf cichlids when their adult size, temperament, space and 23–27°C, pH 6.5–7.5 and 5–12 dGH requirements align. Avoid larger fish that may eat it.

How does this fish arrive alive in the UK?

Tropical Fish Co hand-bags it in pure oxygen inside an insulated poly box, with a heat pack when the weather calls for it. Receive the parcel in person, start filming while it is sealed, open it in one continuous take, show the fish in the sealed bag, then float the bag for 20–30 minutes before releasing the fish without pouring bag water into the aquarium.

Check the public references

• FishBase: Nematobrycon palmeri — accepted identity, family, native river basins, environmental range, diet, group guidance and maximum recorded length.
• Seriously Fish: Nematobrycon palmeri — aquarium footprint, volume, water conditions, feeding, shoaling behaviour and community compatibility.
• OATA: How to look after tetras and pencilfish — group guidance for feeding, water quality, maintenance, gradual stocking and health monitoring.
• RSPCA aquarium environment guidance — biological filtration and the aquarium nitrogen cycle.