Keyhole Cichlid Care Guide

The keyhole cichlid is the rare genuinely peaceful — even shy — cichlid: a calm, monogamous South American that won't bother shrimp, won't harass other fish and won't dig up your plants. The twist is that its welfare risk runs the opposite way to most cichlids. The danger is to the keyhole, not from it; the timid fish is the one that gets bullied, outcompeted and stressed into hiding.

Keyhole Cichlid at a glance

The sourced figures the welfare engine uses to judge Keyhole Cichlid — the parseable key facts.

Where it comes from

Cleithracara maronii is the only species in its genus, from north-eastern South America — the Guianas (the Maroni River is the type locality), the lower Orinoco delta and coastal rivers. Its home is slow-moving or standing blackwater: leaf litter, branches, submerged roots and sparse plants in soft, very acidic, tannin-stained water, with wild pH often down around 4-5. That biotope explains the care. A leaf-littered, branch-tangled blackwater origin means a heavily structured tank with plenty of cover, because a bare tank leaves this shy fish permanently hidden; the soft acidic origin means soft, slightly acidic water is preferred though it adapts to neutral hard tap water; and the slow water means low flow.

Did you know?

• It is the cichlid that hides behind a leaf when a tetra swims by — the gentle, shy antithesis of the aggressive-cichlid stereotype.
• It changes its clothes when scared: a stressed keyhole darkens into a blotchy camouflage pattern and flattens against wood or rock, like a living mood ring.
• Its name is a "lock" in two languages: Cleithracara fuses Greek kleithron ("lock") with Guarani acara ("cichlid"), for the keyhole-shaped flank mark.
• A monogamous pair guards eggs and fry biparentally, with parental care continuing for several months.
• It often lives 7-10 years — long for a small cichlid — and IUCN lists it as Least Concern (assessed 2020).

Tank size — and why

Around 30 US gallons is the realistic recommendation for a pair in a community, with 20 gallons (a 20-long) the absolute floor for two fish only; a rough hobby rule adds about 10 gallons per extra fish. This is a calm mid-water cichlid that reaches roughly 10-12.5 cm, so it needs swim space and, above all, abundant hiding places — not height, and not digging room, because it neither uproots plants nor sifts substrate destructively. Hiding places are its single most important requirement; a planted, structured tank suits it perfectly.

As a guide, a 30-gallon tank comfortably suits about 2 Keyhole Cichlid as a single-species display, leaving room for tankmates.

How big does it really get?

Full-grown Keyhole Cichlid reach about 11 cm (4.3 in) long, but they are usually sold at only about 2.5 cm (1 in) — a typical shop size (estimate). At full size, Keyhole Cichlid needs roughly a 30-gallon tank, about 76 cm long; a common 10-gallon starter kit is only about 51 cm.

Adult size is sourced; the shop size is a typical-juvenile estimate; tank length is approximate for a standard 30-gallon aquarium.

Water parameters in practice

Aim for 24-27 °C and soft, slightly acidic water around pH 6-7, though it is genuinely adaptable across roughly pH 5-7.5 and moderate hardness, which is part of what makes it beginner-friendly. The catch is that adaptable does not mean bombproof: Seriously Fish flags it as susceptible to deteriorating water quality, so it needs stable, clean, regularly-changed water. Chronic nitrate and organics bring on head-and-lateral-line erosion, so don't let the wide tolerance excuse skipped water changes.

Diet & feeding

A foraging omnivore in the wild, taking crustaceans, insects, worms and other small invertebrates from the substrate and litter. In the tank it readily accepts prepared food and thrives on variety: a quality flake or pellet base plus frozen or live bloodworm, brine shrimp, daphnia and small worms. Feed one or two small amounts a day, only what is cleared in a couple of minutes. The feeding note that matters for this species is behavioural — it is a shy, deliberate, sometimes timid feeder that bold, fast tankmates can outcompete, and a keyhole that keeps missing meals while it hides is on a slow decline. Dither fish that signal safety help it feed in the open.

Gear & setup

Soft substrate and lots of cover: driftwood, leaf litter, caves, rockwork and live plants, which it will leave alone. Keep flow low to mimic slow blackwater. A standard covered tank is fine — it is not noted as a strong jumper. The non-negotiable here is structure: hiding places plus calm neighbours are what let a naturally timid cichlid settle and show its personality rather than skulk behind the filter.

Temperament & behaviour

The most peaceful cichlid in the hobby, and a naturally shy one — not aggressive unless breeding. Juveniles are gregarious; on maturity they pair off, and a bonded pair holds only a modest territory, defending the immediate brood patch when spawning but otherwise coexisting calmly. The defining trait is timidity: a new keyhole may hide for weeks, and when stressed it darkens dramatically into a blotchy, barred pattern and presses itself flat against wood or rock to camouflage — a visible mood signal, not an illness. Give it cover, dither fish and calm tankmates and it comes out and earns its keep.

Group & social needs

A monogamous pair-former. Best kept as a pair, ideally by growing out a small group of juveniles and letting a pair form, since the subtle dimorphism makes hand-pairing two adults unreliable. It can also be kept singly. Same-species aggression is minimal — territorial only when breeding — so outside spawning keyholes are easy, undemanding company.

Compatible tank mates (preview)

A short, engine-cleared shortlist — the species TankStocking's welfare engine clears with Keyhole Cichlid and that suit its size and temperament best. Tap any to load the pairing in the planner.

• Bamboo Shrimp (Wood/Fan Shrimp) — Peaceful temperament, similar adult size.
• Boesemani Rainbowfish — Peaceful temperament, similar adult size.
• Bolivian Ram — Uses the bottom zone, peaceful temperament, similar adult size.

A note on the shrimp and snails here: Keyhole Cichlid is peaceful and generally invertebrate-safe — but almost any fish will take very small shrimplets given the chance, so give shrimp dense cover (moss, leaf litter) if you want a colony to grow, rather than expecting every baby to survive.

This engine-cleared shortlist is Keyhole Cichlid's tankmate surface for now — a dedicated tank-mates guide can follow for high-demand species.

Breeding & sexing

Easy to moderate, and a good first cichlid to breed; the main challenge is getting a compatible pair, which is why growing out a group beats buying two adults. Sexing is subtle: mature males grow larger with longer, more-pointed dorsal and anal fins, while females are smaller and rounder, and juveniles can't be reliably sexed. A bonded pair is a monogamous, biparental substrate spawner, cleaning a flat site — a rock, a piece of driftwood, a broad leaf or even the aquarium glass — and laying several hundred eggs (sources span roughly 300 to 600). Both parents guard and tend the brood, and parental care can continue for several months, which is a genuine highlight. First-time pairs often eat their early spawns, which is normal.

Lifespan

About 7-10 years, with some individuals beyond ten under excellent care — notably long-lived for a small cichlid. What shortens it: chronic poor water quality (it is sensitive to deteriorating water despite its adaptability), a poor or monotonous diet leading to head-and-lateral-line erosion and stunting, and — uniquely for this timid fish — chronic stress from aggressive tankmates, where a perpetually-bullied, hiding keyhole eats poorly and slides into secondary infections.

Common mistakes

• Housing it with aggressive or boisterous fish — the number-one keyhole mistake. A timid keyhole kept with cichlid bullies (Jack Dempsey, Oscar, green terror) or pushy barbs hides, starves and declines. Its compatibility constraint is protecting it from stress, not protecting others from it.
• A bare, open tank with no cover — it then hides constantly or wears its blotchy stress colours. Provide driftwood, leaf litter, plants and caves.
• Expecting an instantly bold "personality" fish — it may hide for weeks when new, and impatient buyers assume it is sick. Be patient and add dither fish.
• Too small a tank — a 10 gallon is wrong for a 10-12.5 cm cichlid; a pair wants around 30 gallons realistically.
• Skipping water changes because it "tolerates a wide range." Adaptable to pH and hardness is not the same as tolerant of dirty water — chronic poor quality causes HLLE.

Signs of trouble

• A blotchy, dark, barred pattern and the body pressed flat against wood or rock — its visible stress signal, often from pushy tankmates or a lack of cover.
• Hiding for far longer than the usual settling-in period, and refusing food.
• Weight loss in a fish being outcompeted at feeding time.
• Pitting on the head or an eroding lateral line (HLLE) — poor water or a poor diet.
• Clamped fins and faded colour, with lethargy — general stress or declining water quality.

Is this fish right for you?

Don't buy a keyhole cichlid if your tank is a semi-aggressive community of pushy barbs or bigger cichlids, because the welfare risk here is inverted — it is the keyhole that gets bullied and stressed, not the tankmates. Don't buy one for a bare 10 gallon, or if you want an instantly bold centrepiece, since it is shy and slow to settle. It is generally captive-bred and free of the balloon or dye welfare issues some species suffer, so the main thing is to choose active, well-coloured fish and buy a small group of juveniles if you want a guaranteed pair.

Common questions

Are keyhole cichlids aggressive?

No — they are the rare genuinely peaceful, even shy cichlid, territorial only when breeding. The real concern is the opposite of most cichlids: the keyhole is the one at risk of being bullied, so pair it with calm tankmates and give it cover.

Will a keyhole cichlid eat my shrimp or plants?

No. It won't bother shrimp or destroy plants and ignores normal-sized tankmates; only very tiny fry or shrimplets are a marginal exception. It is one of the most community-friendly and shrimp-safe cichlids you can keep.

Why is my keyhole cichlid always hiding?

It is naturally shy and may hide for weeks when new, especially in a bare tank or alongside pushy fish. Provide driftwood, leaf litter, plants and caves, add peaceful dither fish such as larger tetras, keep boisterous tankmates out, and be patient.

What tank size and tankmates suit a keyhole cichlid?

Around 30 gallons realistically for a pair (20 gallons is the absolute floor for two). Good tankmates are peaceful open-water schoolers as dither, corydoras and other calm community fish; avoid aggressive cichlids and fast, nippy or greedy fish that outcompete and stress it.

How long do keyhole cichlids live?

About 7-10 years, sometimes more with excellent care — long-lived for a small cichlid. Stable clean water, a varied diet, ample cover and calm tankmates are what get it there.

Sources & confidence

Sources & confidence (9 species)

These back the Keyhole Cichlid figures and the previewed tank mates above. Each figure is read from the TankStocking species database (v2026.06); below is the care reference behind it and how confident we are in that data. Confidence reflects the source quality, not whether any pairing is safe. Full source list and the welfare model are on the methodology page.

• Keyhole Cichlid Cleithracara maronii — Seriously Fish (seriouslyfish.com/species/cleithracara-maronii) high confidence
• Bamboo Shrimp (Wood/Fan Shrimp) Atyopsis moluccensis — Aquariadise (aquariadise.com/caresheet-bamboo-shrimp-atyopsis-moluccensis) high confidence
• Boesemani Rainbowfish Melanotaenia boesemani — Seriously Fish; Aquarium Co-Op Boesemani guide high confidence
• Bolivian Ram Mikrogeophagus altispinosus — Seriously Fish (seriouslyfish.com/species/mikrogeophagus-altispinosus) high confidence
• Brilliant Rasbora Rasbora einthovenii — Seriously Fish (seriouslyfish.com/species/rasbora-einthovenii) high confidence
• Bristlenose Pleco Ancistrus sp. — Aquarium Source / aqua-fish.net Ancistrus care guides high confidence
• Bronze Corydoras Corydoras aeneus — Seriously Fish (seriouslyfish.com/species/corydoras-aeneus) high confidence
• Clown Pleco Panaqolus maccus — Fish Laboratory (fishlaboratory.com/fish/clown-pleco); AquariumStoreDepot high confidence
• Congo Tetra Phenacogrammus interruptus — Seriously Fish (seriouslyfish.com/species/phenacogrammus-interruptus) high confidence

Care-guide sources (7)

This guide synthesises the references below; where they disagree, the range and the disagreement are noted in the text above. The figures in the key-facts box are read from the TankStocking species database (v2026.06). Full welfare model on the methodology page.

• FishBase — Cleithracara maronii
• Seriously Fish — Cleithracara maronii
• Wikipedia — Keyhole cichlid
• AquariumStoreDepot — Keyhole Cichlid Care Guide
• Fish Laboratory — Keyhole Cichlid
• Aquadiction — Keyhole Cichlid
• Fishkeeper.co.uk — Keyhole Cichlid

More on Keyhole Cichlid

Related guides on TankStocking — each scored by the same welfare engine as the planner.

This care guide is a sourced planning reference, not veterinary advice — individual fish, filtration and maintenance all matter. Cycle the tank, test your water, and observe your fish. How TankStocking works →