Apistogramma barlowi

By Pet Zone SD Team • October 2026

Overview

Apistogramma barlowi breaks the one rule that holds across almost this entire genus: it isn't a reliable cave spawner. Every other species covered on this site — and the overwhelming majority of the roughly 90 described Apistogramma species — lays eggs inside an enclosed cave and guards them there through hatching. Barlowi instead often practices facultative biparental mouthbrooding, picking eggs up after laying and carrying them in the mouth of one or both parents until they hatch. It's one of only two Apistogramma species documented doing this; the other is A. megastoma, traded for years under the name A. sp. "Kelleri" before its 2017 scientific description. See Breeding below for how inconsistent and genuinely strange this behavior is in practice.

The species comes from small, cool, clear forest streams (igarapés) in the Ampiyacu River system of northeastern Peru, a tributary of the Amazon in the Loreto region. It was formally described in 2008 by German researchers Uwe Römer and Ingo Hahn in the journal Vertebrate Zoology, who named it after George Barlow, a cichlid behavioral biologist. Barlowi is classified within the A. cacatuoides species complex, and prior to its scientific description circulated in the hobby under trade names that are still common today — see Sourcing Notes.

Color & Identification

Adult males carry a disproportionately large head and mouth with noticeably enlarged lips — functional, not just ornamental, since mouth size appears to matter for mouthbrooding capacity and mate choice. The caudal fin is lyrate (forked), split into a yellow lower lobe and a blue upper lobe carrying rows of pale spots. Females are far plainer: a truncate (squared-off) tail, usually with nothing more than a yellow flush at its base, and the expected smaller overall size.

Two non-sympatric color forms exist in the wild and the hobby: a darker "red form" with red facial and body markings, and a paler "white form" lacking red entirely. Both forms are occasionally seen in specialist trade under the names noted in Sourcing below.

Tank Setup

A single pair needs a minimum 24 × 12 inch footprint (roughly 14 US gallons) — SeriouslyFish's own profile calls this size "just about acceptable" rather than ideal, and the species does measurably better with more room. Equipment-wise, a filter rated around 215–270 L/h and a 75–100W heater suit a cooler fishroom (around 68°F ambient); a gentle air-driven sponge filter works well since barlowi, like most apistos, prefers low flow over strong current.

• Substrate: Soft, fine sand — not just for comfort. Substrate texture measurably affects whether this species mouthbroods at all (see Breeding).
• Hardscape: Caves and shaded cover from flowerpots, plastic pipe, or wood roots, even though spawning doesn't always happen inside them the way it does for cave-spawning species.
• Leaf litter: Dried leaves (Indian almond/catappa or oak) add cover, potential spawning sites, and microfauna fry can graze on.
• Planting and light: Dim lighting with soft-water-tolerant plants — Microsorum, Taxiphyllum (Java moss), Cryptocoryne, and floating Ceratopteris (water sprite) all suit the low-light, acidic conditions this species prefers.
• Maturity: Let the tank run biologically mature before adding fish. Barlowi is reported as sensitive to fluctuating organic waste in a freshly cycled setup, more so than some of the genus's hardier beginner species.

Feeding

Mainly carnivorous, feeding on benthic invertebrates in the wild. Offer live or frozen foods regularly — Artemia (brine shrimp), Daphnia, Moina, and chironomid larvae (bloodworm) all work well. Most individuals eventually learn to take dried food, with pellets generally accepted more readily than flakes. As with other apistos, several small feedings suit this species better than one large daily meal.

Temperament & Compatibility

Best kept alone or with small, calm dither fish such as Nannostomus species (pencilfish) — it's generally advised against mixing with other Apistogramma species at all. Reports suggest it's relatively mild toward its own kind compared with some genus relatives, though documentation here is thinner than for widely kept species like cacatuoides or agassizii, simply because far fewer hobbyists have kept it long enough to report back.

Breeding

This is the species' defining trait, and it doesn't happen the same way every time. Barlowi is a facultative biparental mouthbrooder — "facultative" meaning it's an option, not a guarantee, and "biparental" meaning either the male, the female, or both may carry eggs. Substrate appears to be the biggest switch: over fine sand, parents often pick eggs up immediately after laying; over gravel, they may delay several days or skip mouthbrooding altogether, guarding a shallow pit scraped into the substrate instead — essentially the standard Apistogramma approach covered in our genus-wide breeding guide.

Observed spawns add more nuance: over fine sand, females mouthbrooded more often than males; under strong water flow, only males were seen doing it. Courting males also dig and build small sand piles before spawning, a behavior thought to advertise mouth size — and therefore fry-carrying capacity — to both rival males and prospective mates. Because mouthbrooding fry are carried rather than left in an open or enclosed nest, they're arguably better protected from the ammonia and nitrite swings that our breeding guide flags as the single biggest fry-stage failure point in the genus — though a carrying parent that's stressed or disturbed can also abandon or swallow a brood, so minimizing disturbance matters more here than with a cave spawner.

Sourcing Notes

Barlowi isn't a local-fish-store fish. It moves through specialist apisto importers, a handful of dedicated cichlid retailers, and the hobbyist network tracked on forums like apistogramma.com — look for it under its common trade names: A. sp. "Maulbrüter" (German for "mouthbrooder," its original hobby name before formal description), A. sp. "Glaser" for the red color form, or A. sp. "Hauswell" for the white form. See our general sourcing guide for questions worth asking a specialist seller, and our community page for where dedicated apisto breeders and importers tend to surface.

Final Thoughts

Barlowi is worth seeking out for one reason above all others: it's a genuine exception to a rule this entire genus otherwise follows without fail, and watching a parent carry a brood in its mouth rather than guard a cave is not something you'll see from any other apisto on this site. The tradeoff is real — demanding soft-acidic water, a tank that needs to already be mature, and sourcing that takes real effort — but for a keeper who's already comfortable with blackwater specialists like eremnopyge or baenschi and wants something behaviorally different rather than just chemically harder, barlowi delivers that in a way nothing else in the genus does.

Frequently Asked Questions

Why is Apistogramma barlowi a mouthbrooder when every other apisto is a cave spawner?

Because it genuinely is one of just two Apistogramma species documented doing it — the other being A. megastoma, formerly traded as A. sp. "Kelleri" before its 2017 scientific description. Every other species on this site, and the large majority of the roughly 90 described Apistogramma species, lays eggs inside a cave and guards them in place. Barlowi instead often picks the eggs straight up after laying and carries them in its mouth through hatching, a behavior called facultative biparental mouthbrooding — "facultative" because it doesn't always happen, and "biparental" because either the male, the female, or both may do the carrying. It was first documented in the species' 2008 scientific description and remains one of the most unusual breeding strategies in the genus.

What water parameters does Apistogramma barlowi need?

Soft and acidic: pH 4.5–6.5, hardness 1–5 dGH, and 72–84°F (22–29°C). It comes from small, cool, clear forest streams in the Ampiyacu River system of northeastern Peru, a tributary of the Amazon, where one surveyed stream ran about pH 4.8 at 84°F over fine white sand with no vegetation. The tank should be biologically mature before the fish go in — barlowi is reported as sensitive to fluctuating organic waste in a new setup.

How big does Apistogramma barlowi get, and how do you tell males from females?

Males reach about 2.6 inches (65mm standard length); females stay smaller, around 1.6 inches (40mm). Beyond size, males develop a disproportionately large head and mouth with enlarged lips, grow more colorful, and carry a lyrate (forked) tail with a yellow lower lobe and a blue, pale-spotted upper lobe. Females have a plain, truncate tail with little more than a yellow flush at the base — an easy tell once you know what to look for.

How does mouthbrooding actually work in Apistogramma barlowi?

Inconsistently, which is part of what makes it interesting. Over fine sand, parents often pick up eggs right after they're laid; over gravel, they may wait several days or skip mouthbrooding entirely and guard a shallow pit in the substrate instead, the way most of the genus does. In observed spawns, females mouthbrooded more often over fine sand, while under strong water flow only males did. Courting males also build small sand piles before spawning — thought to signal their mouth capacity to prospective mates and rival males.

Where can you buy Apistogramma barlowi?

Specialist channels only — it isn't a mainstream retail fish. It surfaces occasionally through dedicated apisto importers, specialty cichlid retailers, and the hobbyist trade tracked on forums like apistogramma.com, often under older trade names such as A. sp. "Maulbrüter" (German for "mouthbrooder"), A. sp. "Glaser" for the red color form, or A. sp. "Hauswell" for the paler white form. A dedicated cichlid society or the online communities on our community page are a far more realistic route than a local fish store.