- Size: Male to 2.8" (7 cm), female smaller
- Tank: 20 gallons minimum
- pH: 5.5–7.0 (domestic strains tolerate the higher end well)
- Temperature: 73–84°F (23–29°C)
- Hardness: Soft to moderate — more flexible than most apistos
- Temperament: Semi-aggressive, more assertive than cacatuoides
- Difficulty: Intermediate
Overview
Apistogramma macmasteri is a colorful, semi-aggressive dwarf cichlid known for tolerating harder, more neutral tap water than almost any other apisto — and for being frequently mislabeled as the rarer A. viejita. It comes from the upper Rio Meta drainage and Orinoco basin in Colombia, and it's a useful species for a reason that surprises a lot of new keepers: unlike most of this genus, it is not strictly a blackwater fish. Domestic-bred macmasteri handle harder, more neutral tap water noticeably better than nijsseni or true wild-locality apistos — which makes it a good option if your source water isn't especially soft and you don't want to run RO.
Males show vibrant yellow, orange, red, and blue across the body and fins, with red facial markings that give some strains the nickname "red devil." Body shape is compact and elongated, with the usual apisto pattern of larger, more colorful, longer-finned males and smaller, plainer females.
Tank Setup
- Substrate: Sand, for foraging and natural behavior, though this species is less obsessive about sifting than agassizii.
- Hardscape: Clay pots, driftwood, and rock formations for territory and spawning sites. It does well in a planted tank but also wants open swimming space, unlike some of the more cover-dependent species.
- Filtration: Standard gentle-to-moderate flow is fine.
- Water chemistry: Soft and acidic is ideal, but don't panic over moderately hard tap water with a domestic-bred fish — ask your source whether the line has been acclimated to harder water before assuming you need to treat it.
Feeding
An easy, unfussy eater — high-quality dry, frozen, and live meaty foods are all readily accepted. Quality and variety matter more than any special feeding trick with this species.
Temperament & Compatibility
More assertive than the classic beginner apistos. A single male with two to three females works well in a tank with enough structure to break sightlines; in anything smaller, stick to one male, one female. Territoriality peaks hard during spawning — keep other bottom-dwelling or slow-moving tankmates to a minimum if you're trying to breed, and don't mix with dwarf shrimp or other delicate invertebrates once the fish are adult-sized.
Breeding
Conditioning & Spawning
Condition on a varied live and frozen diet. This species breeds readily in the aquarium once a stable pair is established, and — usefully — does so without needing the pristine soft-water conditions some other apistos demand. A cave, clay pot, or coconut shell will typically become the spawning site.
Fry Care
Standard apisto fry care applies: infusoria or fine fry food at first, moving to newly hatched brine shrimp as they grow, with the female handling most of the direct guarding. Regular water changes (weekly, 25% or more) remain essential regardless of how tolerant the adults are of your source water.
A Note on Mislabeling
Macmasteri is frequently confused with, and sometimes deliberately sold as, the much rarer A. viejita — the two are genuinely difficult to tell apart, especially as females. If you're buying "viejita" from a general fish store rather than a specialist, there's a good chance you're actually getting macmasteri. That's not a bad outcome — macmasteri is the more forgiving fish — but it's worth knowing what you're likely holding.
Where to Get Quality Fish
Widely available compared to true viejita, with domestic-bred lines common in the trade. Look for intense, even coloration and active territorial behavior — a washed-out or listless macmasteri is usually a stressed one. See our sourcing guide for more.
Final Thoughts
If your tap water isn't soft and you don't want to fight it, macmasteri is one of the more practical colorful apistos you can keep. It brings real color and personality without the strict blackwater demands of the genus's harder species — a good pick once you've outgrown cacatuoides and want more assertive, striking fish.
Frequently Asked Questions
Does Apistogramma macmasteri need soft water?
Not as strictly as most apistos. Domestic-bred macmasteri handle harder, more neutral tap water noticeably better than nijsseni or true wild-locality apistos, making it a practical choice if your source water isn't soft.
What is the minimum tank size for macmasteri?
20 gallons minimum, with structure — clay pots, driftwood, and rockwork — to break up sightlines and give the fish territory.
Is macmasteri often confused with another species?
Yes. It is frequently mislabeled as, or sold under the name of, the much rarer Apistogramma viejita — the two are genuinely difficult to tell apart, especially as females.
How aggressive is macmasteri?
More assertive than the classic beginner apistos like cacatuoides. Territoriality peaks hard during spawning, so keep other bottom-dwelling tankmates to a minimum if you're trying to breed.
What's the best group to keep macmasteri in?
A single male with two to three females in a tank with enough structure to break sightlines works well; in anything smaller, stick to one male and one female.
Is macmasteri easy to breed?
Yes. It breeds readily once a stable pair is established, and does so without needing the pristine soft-water conditions some other apistos demand.
Apistogrammarama is written and maintained by the aquarium staff at Pet Zone Tropical Fish in San Diego, who have imported and kept South American dwarf cichlids since the store's founding in 2007.