Fossorochromis rostratus

Fossorochromis rostratus at a glance

Fossorochromis rostratus is a Lake Malawi cichlid for keepers who run, or are ready to build, a spacious hard-water aquarium given over to Malawi fish. Each purchase is one live fish at the size you choose, 4–5 cm or 6–7 cm. The size you select is the size supplied, not the adult size. Both sizes sit well below the roughly 10 cm that most Malawi cichlids reach, so most of the planning on this page is about the fish it will grow into rather than the one that arrives.

The deciding question is company. The care sheet from the Ornamental Aquatic Trade Association (OATA) on looking after Malawi cichlids describes them as colourful, diverse and aggressive fish, and advises keeping them only with other Malawi cichlids or some species of Synodontis catfish. That makes this a fish for a Malawi-only aquarium, planned as a group from the outset, rather than an addition to a general community tank.

Name and identity

The accepted scientific name is Fossorochromis rostratus, described by Boulenger in 1899 and recorded under that name in the FishBase species summary for Fossorochromis rostratus. The aquarium trade often spells the genus Fosorochromis, with a single s, and you may find the fish listed that way elsewhere; both spellings refer to the same fish, and this page uses the accepted form. It belongs to the cichlid family, Cichlidae, and to the Malawi cichlids, the large group of cichlids from Lake Malawi, one of the most biodiverse lakes in the world. We sell it under its scientific name rather than a trade nickname.

What each purchase includes

• One fish per purchase. Ordering a quantity of three supplies three fish of the chosen size.
• Two sizes. 4–5 cm and 6–7 cm. Which size can be ordered changes with stock, so check the size menu on this page before you plan around a particular size.
• Room to grow. At either size the fish has a good deal of growing still to do, which is why the aquarium you buy for it matters more than the size you choose.

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

OATA notes that many Malawi cichlids only show differences between the sexes once they are adult, not as juveniles. Young fish like these are therefore sold without a choice of sex, and the balance of males and females in a group becomes clear only as the fish mature.

About the photographs

Gallery images have been digitally enhanced to improve image quality. Natural colour, pattern, size and maturity can vary between live animals.

The gallery shows silvery fish with a row of large dark blotches along the flanks and blue-tinged fins. The fish you receive is a young fish at the size you choose, so expect it to look smaller and less developed than the fish pictured.

Who this fish suits

Use this quick check before you buy. Each point is covered in more detail in the care and compatibility sections further down.

OATA describes Malawi cichlids as usually undemanding aquarium inhabitants that are easy to keep, aggression aside. The conditions they need are specific, though: hard, alkaline water held steady, a large aquarium with oversized filtration and strong aeration, weekly water changes, and a stocking plan that spreads aggression across a well-chosen Malawi group. A keeper who can provide all of that will find the day-to-day care straightforward.

Growth is the part most often underestimated. OATA notes that most Malawi cichlids grow to around 10 cm, but some grow up to 25 cm. Buy the aquarium, filter and companions for a fish that may reach the upper end of that span, and treat the small fish in the bag as the start of that plan rather than its measure.

A planning checklist before you order

Work through these points before the fish goes in your basket. Each one is explained in the sections that follow, and together they decide whether the aquarium is ready for a Malawi cichlid.

1. Test your tap water for pH, general hardness and carbonate hardness, so you know how much buffering the aquarium will need.
2. Plan the whole Malawi group, listing each species you intend to keep and the adult size it reaches, then choose the aquarium to fit that list.
3. Fit an oversized filter and strong aeration, plus a heater and a separate thermometer.
4. Set the rockwork on the base first, then add coral sand or a similar buffering substrate around it.
5. Mature the filter until ammonia and nitrite both read zero.
6. Decide the order of introduction, with the more peaceful species going in first.
7. Have the essentials to hand: a test kit, tap water conditioner, a siphon, a net and suitable food.
8. Keep the delivery day free so someone is in to receive the parcel and film the unboxing.

Space, filtration and substrate

The first rule in OATA’s Malawi care sheet is to buy an aquarium as large as you reasonably can. It recommends at least 200 litres for a reasonably sized community, noting that some more specialist species can live in smaller tanks, and it explains why size matters: the larger the aquarium, the more stable its temperature and water quality will be.

For this fish, read 200 litres as a floor for a Malawi community, not a target. A Malawi group is kept slightly overcrowded to spread aggression, and every fish in it keeps growing after purchase. Work out the adult sizes of all the fish you plan to keep together and size the aquarium for that group, with room for open water as well as rockwork.

Filtration and oxygen

The RSPCA’s guidance on aquarium environments and filters is clear that no fish should be kept without a well set-up and maintained filter. OATA goes further for Malawi cichlids: because successful Malawi communities are crowded, it recommends an oversized filter, together with aggressive aeration so that there is enough dissolved oxygen in the water.

• Choose a filter rated for a larger volume than your aquarium holds.
• Add an air pump, or angle the filter outlet, so the surface is kept moving.
• Leave space around the filter intake so it can be checked and cleaned without dismantling the rockwork.

Substrate, rocks and plants

OATA recommends coral sand or a similar substrate, which helps to buffer the water towards the hard, alkaline conditions Malawi cichlids need. Malawi cichlids will often dig and rearrange the substrate, and that digging will uproot any plants present, so keep to the very hardiest plants or leave them out altogether.

Because digging moves sand around, stand heavy rockwork directly on the base of the aquarium before the sand goes in, so a fish working underneath cannot bring it down. Build a layout with caves and broken-up spaces rather than one solid wall of rock; it gives a busy group more room to spread out, and it is easier to rework later when you need to change the territories.

Hard, alkaline water

Malawi cichlids are, in OATA’s words, a specialised group of fish that need particular water parameters. The values below come from OATA’s Malawi cichlid care sheet, which presents them as a general guide for the group and advises checking any species-specific requirements with your retailer. We recommend them as the working range for Fossorochromis rostratus: aim for steady values near the middle rather than the edges.

Start with your tap water

Tap water varies from area to area, so test yours for pH, general hardness and carbonate hardness before deciding how much buffering you need. The water parameter matcher compares your readings with the values above, and our guide to which aquarium water values to test and why explains what each measurement tells you.

Coral sand or a similar buffering substrate is OATA’s way of holding the water hard and alkaline. Make any adjustment gradually and keep replacement water close to the aquarium’s own readings, because stable pH and hardness matter more to a settled fish than hitting one exact figure.

Temperature

A range of 23–27°C means a heated aquarium in most UK homes. Use a heater suited to the volume and a separate thermometer you can read at a glance, and check it every day. Larger volumes change temperature more slowly, which is one more reason to buy the biggest aquarium you can.

Ammonia, nitrite and nitrate

Ammonia and nitrite should always read zero. OATA warns that Malawi cichlids can be stressed by even the smallest amounts of ammonia, and a crowded Malawi community produces a lot of waste, so test at least once a week and more often while the aquarium is new. Keep nitrate no more than 20 mg per litre above your tap water level; the weekly water change is the main way to hold it there.

As a worked example, if your tap water reads 10 mg per litre of nitrate, the aquarium should stay at or below 30 mg per litre. If it creeps above that between changes, feed a little less, check the filter for blockages and change water more often until the reading settles back.

Maturing the aquarium and stocking in stages

A new aquarium needs a working biological filter before any fish goes in. As the RSPCA explains, fish release ammonia into the water, which is toxic. Beneficial bacteria in a working filter convert ammonia to nitrite, which is also toxic, and then to nitrate, which is safer. Those bacteria take time to build up, which is why the filter has to be matured first.

Our guide on how to set up and mature a new tropical aquarium walks through the process step by step. Before adding any fish, confirm that ammonia and nitrite both read zero, as OATA advises.

Why a Malawi group is built in stages

Malawi communities pull in two directions. OATA recommends a slightly overcrowded group to spread aggression, yet it also warns that overstocking, or stocking too quickly, can cause new tank syndrome: there are not enough nitrifying bacteria to cope with the extra waste, ammonia and nitrite rise to unhealthy levels, and fish may become ill or die. The bacterial population has to grow every time more fish are added and feeding increases.

The answer is to plan the full group on paper, then build it in several batches, testing between each one.

• Filter matured, with ammonia and nitrite at zero, before the first fish.
• Each batch small enough that the readings stay at zero in the days afterwards.
• Feeding increased gradually as the group grows.
• A test kit to hand for the week after every addition.

Building the group this way also fits the order of introduction set out in the compatibility section, where the calmer species go in first.

Feeding and portion control

OATA points out that Malawi cichlids do not all eat the same way. The smaller mbuna are more herbivorous and appreciate Malawi cichlid foods with a high algae content plus fresh vegetables, while some of the larger open-water utaka species may be more predatory and will require pellets with a higher animal content, with frozen foods such as brine shrimp, prawns or cockles.

On our site Fossorochromis rostratus sits with the haps and peacocks rather than among the rock-dwelling mbuna. We suggest building its menu the way OATA describes for the more predatory Malawi cichlids:

• A quality cichlid pellet with a good share of animal content as the everyday food, sized to fit a small mouth at first.
• Frozen brine shrimp for variety.
• Larger frozen foods such as prawns or cockles, cut to size, as the fish grows.

How much and how often

OATA’s rule for Malawi cichlids is to feed only what the fish can eat within a few minutes, twice a day. Overfeeding quickly undoes good water quality: uneaten food breaks down and releases toxic waste into the water, and in a crowded Malawi aquarium that waste adds up fast.

• Scatter food over a wide area so that every fish in the group gets a share, not only the boldest.
• Watch the whole group while it feeds; a fish that hangs back or stops eating is worth a closer look.
• Siphon out anything left once feeding stops, rather than letting it sink into the sand.
• Raise portions gradually as the fish grow and as you add more fish, and test the water after each increase.

For a newly arrived fish

A fish that has just travelled may take a little time before it feeds with confidence. Offer a small portion, remove whatever is left, and try again at the next feed rather than adding more food to tempt it.

Weekly maintenance

Good husbandry matters with Malawi cichlids because they can be stressed by even the smallest amounts of ammonia. A simple routine, repeated every week, keeps the water where it should be.

1. Test the water. Check ammonia and nitrite at least once a week, and compare nitrate with your tap water level.
2. Change water. OATA strongly recommends a partial water change of 25% at least once every week. A siphon lifts solid waste out of the sand at the same time.
3. Treat new water. Add tap water conditioner to remove chlorine or chloramine before the water goes into the aquarium, and bring it close to the tank’s temperature.
4. Check the filter. Look for blockages. If the media needs cleaning, rinse it lightly in the tank water you have just removed. Do not run it under the tap, because any chlorine or chloramine present may kill the beneficial bacteria living in it.
5. Keep a record. Note readings, water changed and any change in behaviour, so a slow drift shows up before it becomes a problem.

Keeping changes gentle

If you buffer your water, prepare the replacement water so its hardness and pH sit close to the aquarium’s. A weekly change should refresh the water without moving the readings, which is far easier on the fish than an occasional large correction.

For scale, a 25% change on a 400-litre aquarium means preparing 100 litres of conditioned, temperature-matched water every week. Plan the containers, or a practical refill method, before the aquarium is stocked rather than after.

Rinsing media in tank water rather than under the tap keeps as much of the bacterial population as possible. In a Malawi aquarium, where the filter carries a heavy load, losing that population can undo weeks of maturing.

Delivery, arrival and settling in

Every order is hand-packed by our team. Fish are hand-bagged in pure oxygen and packed in an insulated poly box, with a heat pack when the weather calls for it. A licensed live-animal courier carries the parcel on a tracked service, and we email the tracking number and your confirmed delivery date so you know when to be in. Full details are on our delivery and Live Arrival Guarantee page.

On the day it arrives

1. Be at the delivery address on the confirmed day. Live fish cannot be left unattended, and the Live Arrival Guarantee requires someone to be there to receive the parcel.
2. Before the tape is touched, start one continuous unboxing video: show the parcel still sealed with the outer box visible, keep filming while you open it in one take, and finish on the fish still inside its sealed bag.
3. Open and inspect the parcel the same day it arrives.
4. Float the sealed bag in the aquarium for 20–30 minutes before releasing the fish.
5. Release the fish into the aquarium without pouring the bag water in.
6. If anything has gone wrong, contact us the same day, by WhatsApp for the quickest reply, with your order number and the unboxing video, and we will arrange a replacement or refund.

Film the video for every delivery. Our licensed courier may ask us for continuous unboxing evidence when we raise a claim, and the video lets us see the fish’s condition before anything was disturbed.

The first week

A new fish adds to the filter’s workload, so test ammonia and nitrite during the first week and keep portions small until it is eating well. Give it time to find its place in the group, and watch for one fish being singled out; the compatibility section explains how Malawi keepers spread that attention.

• Check the fish at each feed: eyes clear, fins whole, breathing steady.
• Keep the routine calm and avoid major changes to the aquarium in the first days.
• Hold back further additions until the new fish is settled and the readings are stable.

Health checks and early warning signs

A healthy Malawi cichlid, as OATA describes it, has clear, bright eyes, undamaged fins and intact scales, shows no ulcers or bumps and swims normally. Every fish varies a little in behaviour and appearance, so learn what normal looks like for yours in the first weeks; changes are far easier to spot against that picture.

Changes worth acting on

What to do first

If you notice any of these, test the water before anything else: ammonia, nitrite, nitrate, pH and temperature. Water quality is the first thing to rule out, and a reading outside the ranges in the water section tells you where to start. If the water is fine and the change persists, get in touch with your readings and a short description, and we can talk it through.

In a Malawi aquarium, health and aggression are closely linked. Damage that keeps appearing on the same fish often calls for a change to the stocking or the layout rather than a treatment; the compatibility section lists the signs to look for.

Temperament and aggression

OATA’s Malawi cichlid guidance is direct: Malawi cichlids vary in size, but they are all aggressive and should be mixed with caution. They are not social fish, and they can be highly aggressive. Plan for Fossorochromis rostratus on that basis from the start.

How Malawi keepers spread aggression

Rather than keeping the peace with a few fish, OATA’s approach is the opposite: keep Malawi cichlids in groups of at least 15, slightly overcrowded, so that aggression is shared across many fish instead of falling on one. Malawi cichlids kept in small groups will often fight.

• Group size. At least 15 Malawi cichlids in the community, in an aquarium large enough for their adult sizes.
• Sex ratio. Where possible, more females than males of each species, so males do not harass one individual female.
• Adding fish. Introduce Malawi cichlids in groups rather than one at a time, so no single fish receives unnecessary aggression while it settles in.
• Order of introduction. Add the more peaceful species first and the more aggressive species later.
• Territories. Rearranging the décor can help to reduce aggression, because the fish have to find new territories.

Planning the balance of males and females

Young fish at these sizes cannot be chosen by sex, so the ratio cannot be set at the point of purchase. Plan the group with that in mind: keep enough fish of each species for the balance to even out, watch the group as the fish mature and differences appear, and be ready to rehome surplus males if one female is being singled out.

Signs the balance needs attention

• One fish hiding constantly, or kept away from food at every feed.
• Torn fins or missing scales on the same fish again and again.
• A single female being pursued by one or more males.
• Aggression that stays high instead of settling after new fish are added.

When you see these, work on the layout and the stocking first: rework the rockwork so territories change, and review the balance of species and sexes in the group.

In a spacious aquarium with the group built this way, a Malawi community is lively and busy. It will not be a calm mixed tank, and it is kinder to the fish to plan for that from the start than to discover it later.

Choosing tank mates

OATA’s rule is short: Malawi cichlids should only be kept with other Malawi cichlids or some species of Synodontis catfish, which also naturally inhabit Lake Malawi. Everything else about choosing companions follows from that.

Matching size and temperament

Adult sizes vary widely across the Malawi cichlids, and a Fossorochromis rostratus bought at 4–7 cm will change the balance of the aquarium as it grows. Choose companions for their adult sizes and temperaments rather than for how they look as juveniles. Browse our African cichlid range with that in mind, and read each species’ own care notes before adding it to the plan.

Why not a community tank?

Fish that come from soft or neutral water would be kept outside their own needs in the hard, alkaline conditions Malawi cichlids require. Peaceful community fish are also a poor match for a group kept deliberately busy to spread aggression. Keeping the aquarium Malawi-only lets you set the water, the décor and the stocking for one set of needs.

Catfish in a Malawi aquarium

OATA names some Synodontis catfish as the exception to the Malawi-only rule, because they also naturally inhabit the lake. Choose a species that shares that origin and check its own care needs; a catfish still has to hold its own among a busy, crowded group.

Questions keepers ask

How big does Fossorochromis rostratus get?

OATA notes that most Malawi cichlids grow to around 10 cm and some grow up to 25 cm. Plan the aquarium, filter and companions for a fish that may reach the upper end of that span, rather than for the young fish that arrives.

What size aquarium does it need?

OATA recommends at least 200 litres for a reasonably sized Malawi cichlid community and advises buying as large an aquarium as you reasonably can. Treat 200 litres as a starting point, size the tank for the adult sizes of the whole planned group, and fit an oversized filter with strong aeration.

How many Fossorochromis rostratus should I keep together?

Plan it as part of a Malawi cichlid community rather than as a single fish. OATA’s guidance is a group of at least 15 Malawi cichlids, slightly overcrowded to spread aggression, with more females than males of each species where possible; small groups will often fight.

Is Fossorochromis rostratus suitable for beginners?

It suits a committed beginner who is ready to set up a large, hard-water, Malawi-only aquarium. OATA describes Malawi cichlids as usually undemanding and easy to keep apart from their aggression; the challenge lies in the tank size, stable water and a well-planned group rather than in daily care.

What does it eat?

Feed Fossorochromis rostratus a quality cichlid pellet with a good share of animal content, sized to its mouth, plus frozen foods such as brine shrimp, adding larger foods such as prawns or cockles cut to size as it grows. OATA advises feeding Malawi cichlids only what they can eat within a few minutes, twice a day.

What temperature and pH does it need?

OATA’s guidance for Malawi cichlids is 23–27°C and pH 8.0–8.6, with general hardness of 12–18°dH and carbonate hardness of 10–15°dKH. Keep the water steady within those ranges, with ammonia and nitrite at zero.

Is Fossorochromis rostratus aggressive?

Yes. OATA describes all Malawi cichlids as aggressive fish that should be mixed with caution. Keep it in a spacious aquarium as part of a slightly overcrowded Malawi group, add fish in groups rather than singly, and rearrange the décor if aggression builds.

Which fish can live with it?

Only other Malawi cichlids or some species of Synodontis catfish, which also occur naturally in Lake Malawi. Choose companions for their adult size and temperament, add the more peaceful species first and the more aggressive ones later, and keep fish from other waters out of the aquarium.

How does it arrive alive in the UK?

Each fish is hand-bagged in pure oxygen, packed in an insulated poly box with a heat pack when the weather calls for it, and carried by a licensed live-animal courier on a tracked service. Be in to receive it, film one continuous unboxing video from the sealed parcel to the fish still in its bag, then float the sealed bag for 20–30 minutes before releasing the fish without the bag water. Send the video and your order number the same day if anything has gone wrong.

Sources and further reading

• FishBase: Fossorochromis rostratus species summary – accepted scientific name and author (Boulenger, 1899).
• Ornamental Aquatic Trade Association: how to look after African Malawi cichlids – water values, aquarium size, feeding, maintenance, health signs and compatibility for Malawi cichlids as a group.
• RSPCA: fish environment and aquarium filters – why every aquarium needs a working, maintained filter.
• Tropical Fish Co delivery and Live Arrival Guarantee page, linked in the arrival section – packing, courier, unboxing video and acclimatisation steps.