Nyasa Blue Cichlid, Zebra M (Pseudotropheus zebra)

Understand this rock-dwelling zebra mbuna

The Nyasa Blue Cichlid, Zebra M (Pseudotropheus zebra) is a freshwater cichlid from Lake Malawi in Africa and belongs to the rock-dwelling group known as mbuna. FishBase records a maximum of 11.3 cm standard length for male or unsexed fish and places it in the cichlid family. This assertive species suits a keeper prepared to plan a dedicated Malawi community with hard, alkaline water, extensive rockwork, mature filtration and carefully screened companions. It is not a general tropical community fish. FishBase now lists it as Maylandia zebra.

In nature, adults occur in rocky areas at depths of 6–28 metres, including shallow, sediment-free habitat and deeper areas where sediment is present. They hold their bodies at right angles to the substrate and comb loose material from the biological growth covering the rocks. They also take plankton in open water. That feeding behaviour explains two central aquarium decisions: build around extensive rockwork and make vegetable matter the basis of the prepared diet rather than relying heavily on animal protein.

The aquarium must combine hard, alkaline water, excellent biological filtration, caves, separated rocky areas and companions selected for compatible water needs and temperament. The species is most appropriate for a keeper prepared to manage territories and monitor aggression rather than someone seeking a peaceful mixed aquarium.

Decide whether this fish fits your aquarium

Choose a dispatch size without confusing it with growth

Use the live size selector to choose the dispatch label that suits your aquarium plan. Labels include 3–4 cm, 4–5 cm, 6–7 cm, 7–9 cm and XL. The size you select is the size supplied, not the adult size. A smaller dispatch choice does not reduce the permanent space, filtration or compatibility requirements.

One purchase quantity supplies one animal of the selected option. A gallery scene may show two fish, but that visual composition does not change the purchase unit. Plan the number of animals deliberately around the aquarium footprint, established residents, filtration capacity and intended male-to-female structure before changing the basket quantity.

Sex is guaranteed only when the selected option explicitly states male or female. This Nyasa Blue Cichlid, Zebra M listing has no sex-guaranteed option.

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

Use the selector as a practical decision

Do not infer sex, maturity or origin from a size label. Colour can also vary, so use behaviour, space and water requirements—not an expected shade—as the basis of the purchase decision.

Plan the aquarium around the adult allowance

FishBase records a maximum of 11.3 cm standard length for male or unsexed fish. Seriously Fish uses 15.2 cm standard length for aquarium planning, together with a 120 × 38 cm base and approximately 205 litres. Use the larger planning length as an allowance rather than a guaranteed outcome, and prioritise the 120 cm footprint because territories and escape routes need horizontal room.

The practical starting point is therefore a rocky aquarium around 205 litres with a base of at least 120 × 38 cm. Volume alone is not enough: a tall tank with a short base can hold a similar number of litres while offering fewer separate territories. Lay out the rocks before stocking and confirm that caves, separated rocky areas and open sand can coexist without reducing the usable swimming area to narrow dead ends.

Seriously Fish gives 22–28°C, pH 7.6–8.6 and 10–25 dGH for the species. OATA’s Malawi-cichlid group guidance narrows the routine aquarium target to 23–27°C, pH 8.0–8.6 and 12–18 dGH. Use those narrower values while keeping ammonia and nitrite at zero.

Decisive planning figures

Build caves and sight breaks before stocking

Fill much of the aquarium with rock piles arranged to create numerous caves, crevices and broken lines of sight. The layout should let a chased fish move away without entering another single-exit trap. Keep an open area of sand as usable swimming and feeding space, and arrange the rock structure so digging cannot undermine it.

Build from the fish’s behaviour outward

1. Place the main rock structure first. Create several separate zones across the length of the tank instead of one central cave claimed by the strongest fish.
2. Add sand around the stable structure. Sand suits the Malawi layout described for this species and allows the fish to dig and rearrange loose substrate.
3. Check every route. Look from each end of the aquarium. If every cave is accessible from one dominant position, add another rock pile or turn a rock to separate the areas.
4. Preserve open water. Leave enough clear space for normal swimming and for food to be distributed without every portion landing inside one territory.

Bright lighting is useful because it encourages algae and the microorganisms associated with it to grow on exposed surfaces. This complements the fish’s natural grazing behaviour, but it does not replace a measured prepared diet. Feed the fish directly and treat growth on the rocks as environmental enrichment.

Rooted plants are likely to be disturbed as Malawi cichlids dig and rearrange the substrate. If greenery is part of the design, choose hardy plants that can be attached to décor rather than depending on an undisturbed root bed. Do not sacrifice caves or separated rocky areas simply to preserve a planted layout.

Test the layout before adding fish

• Confirm that the rocks cannot shift when the sand beneath them is moved.
• Make sure the filter intake and outlet remain unobstructed.
• Check that waste can be siphoned from the open areas during weekly maintenance.
• Count usable retreats rather than decorative holes that are too shallow or exposed.

A successful layout is not the one with the greatest quantity of stone. It is the one that divides the aquarium into several defensible but escapable areas while leaving room for water circulation and routine cleaning.

Hold stable hard, alkaline water

Set the routine target at 23–27°C, pH 8.0–8.6 and 12–18 dGH. These figures are the overlap between the species ranges from Seriously Fish and OATA’s narrower Malawi-cichlid group guidance. Test the source water before choosing décor or livestock, because a stable aquarium begins with knowing what enters during each water change.

Use our aquarium water chemistry guide to understand temperature, pH, hardness, ammonia, nitrite and nitrate as separate measurements. Then enter the measured figures in the water matcher and compare them with this fish’s working range. Do not treat a clear-looking aquarium as proof that these values are suitable.

Work through the numbers in order

OATA advises that nitrate should not exceed 20 mg per litre above the normal tap-water level. Record the tap-water reading as well as the aquarium reading so the comparison has a genuine baseline.

Coral sand or a similar substrate can help buffer Malawi water. Test rather than assuming that substrate alone will hold the required chemistry, especially after maintenance or a change in the water entering the aquarium.

For an aquarium around 205 litres in a room near 20°C, Seriously Fish gives a heater-planning range of roughly 200–300 W. Choose and position heating equipment around the actual aquarium, room temperature and water circulation, then confirm the result with measured temperature rather than the heater dial alone.

Match filtration and maintenance to the bioload

A mature biological filter is essential. RSPCA aquarium welfare guidance explains that fish release toxic ammonia, which beneficial filter bacteria convert first to toxic nitrite and then to safer nitrate. The filter therefore protects the fish only when it is established, flowing correctly and maintained without destroying those bacteria.

Seriously Fish recommends turnover of four to five times the aquarium volume each hour. For a tank around 205 litres, that calculation gives approximately 820–1,025 litres per hour. Treat the stated flow as a planning figure: media, pipework and blockages can affect real circulation, so inspect the aquarium for quiet waste traps as well as reading the filter label.

Use a fixed weekly routine

1. Test first. Measure ammonia and nitrite at least weekly and keep both at zero. Record nitrate against the normal tap-water level.
2. Change 25% of the water at least once a week. This is OATA’s recommended partial water-change schedule.
3. Treat replacement tap water. Use conditioner to remove chlorine or chloramine before the new water enters the aquarium.
4. Siphon accessible waste. Remove settled solids from open substrate without dismantling every territory at once.
5. Inspect flow and aeration. Check the filter for blockages and make sure the surface movement supports strong oxygenation.

If filter media needs cleaning, rinse it lightly in aquarium water removed during the water change. Do not wash established biological media under the tap, because chlorine or chloramine may kill beneficial bacteria and reduce the filter’s capacity to process waste.

Malawi communities may place a heavy load on filtration, particularly when stocking is designed to spread aggression. OATA therefore recommends an oversized filter and strong aeration for these aquariums. Extra fish must never be used as an aggression strategy unless the aquarium has the footprint, mature biological capacity, oxygenation and maintenance routine to carry the resulting waste.

Respond to an abnormal test

If ammonia or nitrite rises above zero, stop adding fish, reduce the immediate waste burden and perform the tested, conditioned-water maintenance needed to restore safe readings. Check for blocked flow, excess food and recent stocking changes. Resume stocking decisions only after repeated tests show that the biological filter is processing the aquarium’s load.

Make vegetable matter the basis of every feeding plan

Build the aquarium diet around vegetable matter. The wild fish combs loose material from the growth covering rocks and also takes plankton, while the species profile advises that high-protein foods should not form the main diet. Suitable staples include spirulina flakes, specialised Malawi cichlid food with a high algae content, blanched spinach, nori and other green foods.

Feed only what the fish can finish within a few minutes, twice a day. Start with a deliberately small portion, watch every piece and stop adding food when interest falls or food begins reaching places where it will decay. Uneaten food adds waste, increases the demand on the filter and can contribute to dangerous water-quality changes.

Separate staples from treats

The occasional animal-protein treat is an addition, not a substitute for the algae-rich basis of the diet. Seriously Fish warns against overdoing protein and notes that animal meat interferes with the digestive system of mbuna. The profile also highlights a tendency towards obesity, so assess body condition rather than increasing portions simply because the fish continues to approach at feeding time.

Use feeding behaviour as a checkpoint

• If food remains after a few minutes, reduce the next portion and remove accessible leftovers.
• If one fish monopolises a single feeding point, distribute small portions across the open area so others can feed without entering that territory.
• If interest in food drops, check temperature, ammonia, nitrite and recent aggression before changing the diet.
• If body condition increases, reduce excess quantity and protein treats while keeping the vegetable-based staple balanced.

Do not depend on naturally growing algae as the sole food. Its quantity and composition vary with lighting and aquarium conditions, while a measured feeding routine lets you control portions and notice changes in appetite.

Prepare the aquarium before the fish arrives

Mature the aquarium and biological filter before adding livestock. Our first tropical aquarium guide explains how to prepare the system before fish arrive. For this mbuna, the completed preparation also includes the rocky territory layout, stable 23–27°C water, pH 8.0–8.6, hardness of 12–18 dGH, and zero ammonia and nitrite.

Complete the pre-arrival check

• Run the heater, filter and aeration long enough to confirm stable operation.
• Test temperature, pH, hardness, ammonia and nitrite rather than relying on equipment settings.
• Finish the caves and separate rocky areas before the fish enters the aquarium.
• Compare every resident with the compatibility screen before introducing another territorial cichlid.
• Increase stocking slowly enough for the beneficial bacterial population to respond to added waste and feeding.

Be present to receive live fish; the parcel must not be left unattended. Follow the current delivery, acclimatisation and Live Arrival Guarantee policy.

Follow the store arrival steps

1. Start filming before opening. Film every delivery continuously from the sealed parcel, with the outer box visible.
2. Open the parcel in the same continuous take. Show the fish while it is still inside the sealed bag before anything is disturbed.
3. Float the bag. Float the sealed bag in the aquarium for 20–30 minutes before releasing the fish.
4. Transfer the fish. Never pour the bag water into the aquarium.

After release, observe swimming, breathing and interactions. OATA advises watching for changes such as hanging at the surface, sitting on the bottom, erratic swimming, abnormal breathing, increased hiding or reduced feeding.

Use the first week to check the plan

Watch whether the new fish can leave a chase, reach food and occupy cover without remaining trapped at the surface or bottom. Check for rapid breathing, persistent hiding, loss of appetite, colour change, erratic swimming or damaged fins. Test the water promptly when behaviour changes rather than assuming every problem is territorial.

Additions increase both social pressure and biological load. Do not add another group simply because the first introduction appears calm for a few hours; allow the filter readings and territorial pattern to settle before making the next stocking decision.

Read behaviour and body condition every day

Establish a normal daily picture for the fish: where it swims, which cave it uses, how strongly it feeds, how quickly the gill covers move and how it responds to neighbouring territories. Individual behaviour can vary, but a change from that animal’s usual pattern gives you a practical reason to test the aquarium and inspect the social layout.

Pair each sign with an immediate check

Also watch for damaged fins, bumps, ulcerated areas, loss of scales, reduced food intake and an increase or decrease in body condition. These signs do not all have the same cause, so begin with measured water quality and direct observation rather than applying a treatment at random.

Use first-month checkpoints

• After each introduction: confirm that every fish can reach cover and feeding areas.
• At each weekly test: compare ammonia, nitrite and nitrate with the preceding readings.
• At each water change: inspect the filter flow, substrate waste and stability of the rockwork.
• Before another addition: reassess territory use, aggression and biological capacity.

A fish that eats eagerly can still be under territorial pressure, while a clear aquarium can still contain ammonia or nitrite. Combine appearance, behaviour and test results before deciding that the system is functioning well.

Screen every proposed companion before mixing

Seriously Fish describes this zebra as one of the more aggressive mbuna and excludes it from the general tropical community aquarium. Avoid gentle mbuna such as Aulonocara peacock cichlids. OATA limits the broader compatibility field to other Malawi cichlids and some Lake Malawi Synodontis, but that category is only the start of the decision—not a universal tank-mate promise.

Screen each proposed companion for adult planning size, territorial strength, swimming behaviour, diet, hard alkaline water and its ability to use the rock layout. A fish requiring softer water fails the water screen even if its temperament appears robust. A peaceful Malawi fish can fail the behaviour screen even when its water values match.

Apply the screen in this order

1. Water: require compatibility with 23–27°C, pH 8.0–8.6 and 12–18 dGH.
2. Community type: keep the plan within an intentionally designed Malawi aquarium, with only carefully assessed Lake Malawi Synodontis considered outside the cichlid group.
3. Temperament: exclude gentle species that cannot withstand persistent territorial pressure.
4. Space: make sure the adult plan fits the footprint after rocks, caves and separate areas are installed.
5. Sex structure: use three females per male where fish are reliably sexed, and keep no more than one male in an aquarium below 200 litres.

OATA’s broad Malawi guidance discusses groups of at least 15 and slight overstocking to spread aggression. Do not read that figure as an instruction to place 15 fish into every 200-litre aquarium. Species mix, adult sizes, footprint, filtration and aeration must all carry the proposed population.

No fixed list makes every Malawi combination safe. Temperament varies between individuals and changes as territories form. For a stocking and compatibility assessment, ask us with the aquarium dimensions, volume, water values, filter capacity and the exact residents you intend to mix.

You can also browse the African cichlid collection when building a shortlist, but apply this full screen to every candidate before treating it as part of the plan.

Manage territories instead of relying on luck

A carefully screened species mix can still produce aggression if the layout gives one fish control of every cave or if additions are made in the wrong order. Build several separated rocky areas, distribute cover across the full base and preserve routes around the rock piles. The aim is to interrupt pursuit and divide attention, not to create one narrow refuge where a subordinate fish remains trapped.

Choose an addition strategy

A female-to-male ratio of three to one can spread male attention when the fish are reliably sexed. The ratio does not compensate for a short aquarium, weak filtration or a dominant male controlling the whole rock structure. In tanks below 200 litres, the species profile advises no more than one male.

Stocking intended to spread aggression increases feeding competition, waste and oxygen demand. Use an oversized filter, strong aeration and the weekly 25% water-change routine before considering a denser Malawi community. Never increase numbers merely to solve chasing when the existing aquarium cannot support the resulting adult population.

Distinguish display from harmful pressure

Brief chasing around a claimed cave may occur in a territorial group. Repeated pursuit becomes a practical concern when a fish cannot leave cover, reach food, swim normally or maintain intact fins and scales. Darkening, paling, increased hiding, abnormal breathing or loss of appetite strengthens the reason to intervene in the stocking plan.

Review the community again as fish grow. A dispatch-size group that initially shares the aquarium may require more distinct territories and stronger management later. Adult planning, rather than calm behaviour on the first day, determines whether the combination has a workable future.

Answer the key questions before choosing this fish

How big does Nyasa Blue Cichlid, Zebra M (Pseudotropheus zebra) get?

FishBase records a maximum of 11.3 cm standard length for male or unsexed fish. Plan its permanent aquarium around that adult figure rather than the dispatch size.

What size aquarium does it need?

Plan around the Seriously Fish reference of approximately 205 litres with a base of at least 120 × 38 cm, sand, stable rockwork, caves, mature filtration and strong aeration.

How many Pseudotropheus zebra should I keep together?

Plan a carefully managed Malawi community rather than a small casual group. OATA discusses Malawi groups of at least 15, while Seriously Fish advises three females per male and no more than one male below 200 litres; the aquarium must support the complete adult population.

Is Nyasa Blue Cichlid, Zebra M suitable for beginners?

It is better suited to a keeper prepared to manage an aggressive mbuna, hard alkaline water, territorial rockwork and carefully screened companions than to someone seeking a peaceful general tropical community.

What does this fish eat?

Feed algae-rich Malawi food, spirulina flakes and suitable green foods twice daily, giving only what it finishes within a few minutes. Keep bloodworm or Artemia treats small and limited to a couple of times a week.

What temperature and pH does Pseudotropheus zebra need?

Keep it at 23–27°C, pH 8.0–8.6 and 12–18 dGH; these values are the overlap between the Seriously Fish species ranges and OATA’s Malawi-cichlid group guidance. Keep ammonia and nitrite at zero.

Is Nyasa Blue Cichlid, Zebra M aggressive or likely to nip fins?

Treat it as an aggressive, territorial mbuna. Avoid general tropical communities and gentle Aulonocara peacock cichlids, and intervene if repeated pursuit prevents another fish from feeding, swimming normally or keeping its fins intact.

Which animals can live with it?

Consider carefully screened Malawi cichlids with compatible adult size, temperament and water needs, or some Lake Malawi Synodontis. No named companion is universally safe, so assess the complete stocking plan and aquarium footprint.

How does this fish arrive alive in the UK?

Someone must be present to receive the parcel. Start a continuous video before opening every delivery, showing the sealed parcel, its opening and the fish still in the bag; then float the bag for 20–30 minutes and never pour the bag water into the aquarium.

References for identity and care

• FishBase species summary — identity, distribution, wild habitat, feeding biology, environmental values and recorded length.
• Seriously Fish species profile — aquarium footprint, water ranges, diet, rockwork, filtration and behaviour.
• OATA African Malawi cichlid guidance — routine water targets, feeding frequency, maintenance, group planning and introductions.
• RSPCA aquarium welfare guidance — biological filtration and nitrogen-waste processing.