Soloni Synodontis (Synodontis soloni)

Choose a Congo squeaker for a medium community aquarium

The Soloni Synodontis (Synodontis soloni) is a squeaker catfish from the Congo River in the Democratic Republic of the Congo. FishBase places it in the rapids just below Pool Malebo (the old Stanley Pool), in Pool Malebo itself and in the Ubangi, and Planet Catfish adds Libenge. It reaches about 15.5 cm, which makes the Soloni Synodontis one of the more manageable members of a genus that includes some very large fish.

It belongs to the Mochokidae, the family of squeakers and upside-down catfishes. Every Synodontis has a hard bony cap over the head with a pointed extension behind the gill opening, called the humeral process, stiff serrated first rays in the dorsal and pectoral fins, and a forked tail. They are called squeakers because they make an audible sound by rubbing the base of the pectoral spine against the shoulder girdle when disturbed.

Check the names on the label

The species name honours Alexandre Solon, a young traveller who, according to FishBase, helped Captain Capra collect fish in the Congo and died there shortly afterwards. Boulenger described the species in 1899 from fish collected in the Congo River. Browse our other Synodontis squeakers to compare sizes and patterns.

Know exactly what you receive

One purchase supplies one live Soloni Synodontis. The size option is "Standard": the fish is sent at the size currently available, which is smaller than the adult size. Sex is not chosen or guaranteed, and young Synodontis cannot be sexed by eye.

The photographs show the type of fish, not the individual you will receive. Boulenger described the adult as olive-grey on the back, marbled with brown, white underneath, with round brown spots on the dorsal and caudal fins. Pattern varies between individuals and changes with age, lighting and mood, so expect some difference from the pictures.

Plan the group before you order

• One fish: the simplest choice for a community aquarium, with no competition for caves.
• Two or more: possible in a larger tank, provided each fish has its own cave or shelter well apart from the others.
• Mixed Synodontis: plan the caves first; Seriously Fish reports that related species become territorial towards other Synodontis as they mature.

Before you order, read our delivery and Live Arrival Guarantee information and have the aquarium ready and matured.

Plan the aquarium around a 15 cm adult

Planet Catfish gives a maximum of 155 mm standard length, measured from the snout to the base of the tail, while FishBase gives 15.5 cm total length, which includes the tail. Whichever is right, plan for a solid, spiny fish of around 15 cm with long barbels, not the size that arrives.

No source publishes a minimum aquarium for S. soloni. Seriously Fish recommends a 90 × 30 cm base for Synodontis nigrita, which grows to 175 mm standard length, so we treat 90 × 30 cm as the floor for this slightly smaller fish. If you keep more than one Synodontis, or a lively shoal above it, choose a tank of 120 cm or longer so each fish can claim its own corner.

Run a three-step space check

1. Measure the base: at least 90 cm long and 30 cm from front to back for one fish.
2. Count the caves: one per Synodontis plus a spare, spaced along the tank rather than grouped together.
3. Work out the true volume: our tank volume calculator turns your dimensions into litres for choosing the filter and heater.

Place the aquarium away from radiators, windows and draughts, as OATA's catfish care sheet recommends, and run a heater all year round. A lid stops a startled fish jumping.

Build caves and shade for a night-active catfish

Like most Synodontis, it spends the day in a cave or under wood and becomes active as the light fades. For the genus, Seriously Fish recommends a dimly lit aquarium with a soft substrate and rocks, driftwood and twisted roots arranged to form hiding places, with floating plants to soften the light. That layout works well here.

Wild fish come from rapids and the large pool below them, so a layout of rounded stones, wood and open sand fits the species better than a dense plant thicket. Robust plants such as Anubias tied to wood add cover without taking floor space.

Divide the floor by function

Use smooth sand or fine gravel. OATA points out that catfish have sensitive barbels and need a soft bottom to avoid injury. Bed rocks onto the glass, not on top of the sand, because a Synodontis digs under stones and can bring a loose stack down.

Keep the water warm, steady and well oxygenated

Planet Catfish and FishBase both give 23–25°C. Neither publishes pH or hardness for this species. For a guide we use the values published for another Congo-basin Synodontis: FishBase gives pH 6.0–7.5 and hardness 4–15 dH for S. notatus. Most UK tap water, once conditioned, falls near this range, and a steady reading matters more than an exact one.

Match your tap water to the range

The ammonia, nitrite and nitrate limits come from OATA's catfish guidance. Treat every water change with a conditioner, because water companies add chlorine or chloramine that harms fish and filter bacteria. Your water company's postcode checker shows how hard your supply is, our water matcher compares your readings with this fish's range, and our water chemistry guide explains each reading.

Filter for a fish from the Congo rapids

A fish collected in and below rapids is used to moving, oxygen-rich water. Give it a filter rated for well over the tank volume each hour and point the outlet so it ripples the surface. Seriously Fish suggests a turnover of four to five times the tank volume per hour for the larger S. notatus, which is a sensible target here too. Our guide to aquarium filtration explains how to choose and maintain one.

Follow a weekly routine

1. Test ammonia, nitrite and nitrate before any maintenance.
2. Change about 25% of the water; OATA gives this as the weekly figure.
3. Siphon the open sand and the area in front of each cave, where waste collects.
4. Check the heater reading against a separate thermometer.
5. Rinse filter media only in water taken from the tank, never under the tap, to protect the filter bacteria.

Add fish gradually. OATA explains that filter bacteria must grow each time stocking and feeding increase; stocking too quickly raises ammonia and nitrite and causes "new tank syndrome". A catfish that feeds at night can hide a water problem for days, so keep testing even when the tank looks perfect.

Feed an omnivore after lights-out

No feeding study exists for S. soloni. For the genus, Seriously Fish describes Synodontis as omnivorous and unfussy: frozen, live and dried foods are all taken, along with vegetable matter such as shelled peas and cucumber, which they rasp with the teeth in the lower jaw. OATA advises feeding catfish only what they can eat within a few minutes, once a day.

Build one measured meal

• Staple: a sinking catfish pellet or tablet that reaches the sand intact.
• Meaty food: thawed frozen bloodworm, brine shrimp or mysis two or three times a week.
• Greens: a slice of blanched cucumber or a few shelled peas now and then; remove leftovers the next morning.
• Timing: feed shortly after lights-out, when the fish leaves its cave and faster tank mates have settled.
• Portion: enough to be cleared within a few minutes of the fish finding it.

Watch the belly. A well-fed Synodontis has a gently rounded underside. If it looks hollow, feed closer to its cave and later in the evening rather than simply adding more food.

Introduce it calmly to a mature aquarium

Only add the fish to a filtered aquarium that has run long enough to process waste, with ammonia and nitrite at zero and the temperature in range before it arrives. OATA recommends double-bagging catfish because their spines can pierce a bag, and acclimatising with the aquarium lights off: float the sealed bag for about 10 minutes to match the temperature, then add small amounts of aquarium water to the bag over up to 20 minutes, and release the fish with as little bag water as possible. Our guide on how to acclimatise new fish goes through each step.

Use a first-week checkpoint plan

Expect to see little of it at first. A new Synodontis often stays hidden for several days and comes out mainly after dark. A fish that hangs at the surface, breathes rapidly or lies on its side is not settling and needs a water test straight away.

Choose tank mates it cannot swallow

Its own temperament has not been described in the sources we checked, so the advice here follows the genus. Seriously Fish advises that medium and large Synodontis should not be kept with any fish small enough to be eaten, and names African tetras, West African cichlids, mormyrids, knifefish, gouramis and larger rasboras and barbs as good companions for related species. It also notes that many become territorial towards other Synodontis as they mature.

Screen each companion

For other Synodontis of a similar size, see the Vermiculated Synodontis and the Large-Spot Synodontis, or the much smaller Black Upside-Down Catfish. Our kribensis care guide covers the most popular West African cichlid companion. Check a planned mix with our tank mates tool, and browse all catfish and plecos, the wider range of African catfish or other bottom-dwelling fish.

Handle the spines and watch for problems

The serrated dorsal and pectoral spines lock upright when the fish is alarmed and catch easily in netting. OATA warns that most catfish carry spines on the pectoral fins and just behind the gills and should be handled with care. Guide the fish into a container rather than lifting it in a net whenever you can.

OATA describes a healthy fish as having clear eyes, undamaged fins, no ulcers or bumps, normal swimming and steady breathing. Learn what normal looks like for your fish in the first month, including where it rests and when it comes out to feed.

Pair each sign with an action

Do not diagnose from a single sign. Most changes in behaviour follow a water-quality problem, so test first, note the readings and any recent changes, and then decide what to do.

Understand what is known about breeding

Planet Catfish lists the Soloni Synodontis as unreported in the aquarium, and there is no breeding report for it. FishBase records only that it lays eggs and forms distinct pairs when breeding. Studies of wild Synodontis cited on the species' Wikipedia page suggest that the genus spawns in the flood season, with pairs swimming together, which is difficult to recreate at home.

Tell males from females

Adult Synodontis can be sexed by the shape of the genital papilla behind the vent, which Planet Catfish and Seriously Fish describe in detail; this means handling a spiny fish upside down and is not something to try on a new arrival. Females tend to grow slightly larger and plumper than males of the same age. Seriously Fish notes that most Synodontis take two years or more to mature, so a young fish will not show either sign.

Answer Soloni Synodontis buying questions

What is a Soloni Synodontis?

It is Synodontis soloni, a squeaker catfish (family Mochokidae) from the middle and lower Congo basin in the Democratic Republic of the Congo, where it lives in and below the rapids at Pool Malebo and in the Ubangi. Planet Catfish lists it as the Scissortail Synodontis.

How big does Synodontis soloni grow?

About 15.5 cm. Planet Catfish gives 155 mm standard length and FishBase 15.5 cm total length, so the two sources measure it differently; plan for a fish of 15 cm or a little more.

What size aquarium does it need?

No minimum is published for this species. We use the 90 × 30 cm base Seriously Fish gives for the similar-sized Synodontis nigrita as the floor, and suggest a tank of 120 cm or longer if you keep more than one Synodontis.

What temperature does it need?

Planet Catfish and FishBase both give 23–25°C. No pH or hardness values are published for it; we suggest pH 6.5–7.5 and soft to medium-hard water, which sits inside the published ranges for other Congo-basin Synodontis.

Does it swim upside down?

Synodontis soloni belongs to the upside-down catfish family, but none of the sources we checked describes it as a habitual upside-down swimmer. Expect it to rest in caves and under wood and to forage along the bottom.

Is it a good community fish?

For a community of medium-sized fish, yes. Do not keep it with fish small enough to swallow, and expect some squabbling with other Synodontis over caves as it matures, as Seriously Fish reports for related species.

Why is it called a squeaker?

Synodontis make an audible sound by rubbing the base of the pectoral fin spine against the shoulder girdle. You may hear it when the fish is netted or handled.

How many fish come with one purchase?

One live fish of the standard size currently available. Sex is not chosen or guaranteed.

Consult the care references

• Planet Catfish: Synodontis soloni — names, type locality, size, distribution, temperature and breeding status, plus the features shared by every Synodontis.
• FishBase: Synodontis soloni — classification, distribution, maximum length, temperature and the origin of the species name.
• Wikipedia: Synodontis soloni (Boulenger 1899 description and IUCN notes) — Boulenger's description of the colour, barbels, spines and adipose fin, and the IUCN notes on range and threats.
• FishBase: Synodontis notatus — classification, distribution, maximum length and water range.
• Seriously Fish: Synodontis nigrita — the false upside-down catfish: size, aquarium base, water range, behaviour and how often it swims inverted.
• Seriously Fish: Synodontis notatus — size, aquarium base, water range, aquarium layout, diet, compatibility, sexing and the regional spot variants.
• OATA: How to look after freshwater catfish — UK guidance on catfish water quality, spines, acclimatisation, feeding and weekly water changes.
• Tropical Fish Co delivery policy — current dispatch days and Live Arrival Guarantee terms.