| Scientific name | Pterophyllum scalare (Rio Nanay locality form) |
| Common names | Rio Nanay angelfish, Nanay spotted scalare, Peruvian wild angelfish |
| Origin | Rio Nanay, a blackwater tributary of the Amazon near Iquitos, Peru |
| Adult size | About 5–6 in (13–15 cm) body length, 8–10 in (20–25 cm) tall including fins |
| Minimum tank | 40 gallons for a proven pair, 75 gallons or more for a group of 5–6, at least 20 in (50 cm) tall |
| Water parameters | 80–86°F (27–30°C), pH 4.5–6.5 and 0–3 dGH for wild fish, up to pH 7.2 and 8 dGH for F1 |
| Temperament | Peaceful in a group, territorial once paired, will eat anything small enough to swallow |
| Care level | Advanced for wild-caught, intermediate for F1 |
| Lifespan | Commonly reported as 8–10 years in stable conditions |
The Rio Nanay angelfish is one of the most requested wild Pterophyllum scalare forms in the hobby, and also one of the most misrepresented. It is not a separate species and it is not a line-bred “strain” — it is a locality form of P. scalare from a single blackwater river system in the Peruvian Amazon. This guide covers where the fish comes from, what changes when you keep wild-caught Rio Nanay adults instead of tank-bred F1 stock, how to spot a mislabeled fish, and the water, diet, and acclimation routine that keeps wild scalare alive.
Where the Rio Nanay Is, and Why Its Angelfish Look the Way They Do
The Rio Nanay is a blackwater tributary that meets the Amazon near Iquitos, in the Peruvian Amazon. Blackwater here means what it means everywhere in the basin: water stained the color of strong tea by tannins from decomposing leaf litter, almost no dissolved minerals, and an acidity most hobby test kits barely register. Field reports from the Nanay generally describe pH in the 4.5 to 6.0 range, conductivity in the low tens of microsiemens, and water temperatures around 79–86°F by season.
That environment shapes the fish. Rio Nanay scalare are commonly described as having a compact, deep body with heavy red-brown to rust-colored spotting scattered across the flanks and into the dorsal and anal fins — which is why the trade name for the fish we import is usually written as the Rio Nanay "spotted" scalare. Under good conditions the vertical bars go near-black against a warm silver-gold base. Spotting intensity varies between individuals and increases with age, so juveniles rarely show what an adult shows.
Two things follow. First, the fish evolved in water so soft that hardness, not temperature, is usually the limiting factor in a home tank. Second, the same river produces other blackwater specialists — the wild Rio Nanay green discus comes out of the same drainage, which makes a genuine single-river biotope possible rather than a vague "Amazon" theme. If blackwater chemistry is new to you, our blackwater aquarium setup guide covers tannins and botanicals in more depth.
Wild-Caught vs. F1 Rio Nanay Angelfish: The Difference That Actually Matters
F1 means first captive-bred generation from wild-collected parents. Genetically an F1 Rio Nanay is the same fish as its wild parents. Physiologically it is not, because it hatched and grew in captive water, on captive food. That single difference drives almost everything below.
Wild-caught Rio Nanay
- Needs soft, acidic water. Above roughly 8 dGH and pH 7.5 you typically get faded color, clamped fins, and a slow decline rather than a quick death, so the problem is easy to miss.
- Much less tolerant of nitrate. Keep it under 20 ppm, under 10 ppm if you want to spawn them.
- Sensitive to shipping stress and slower to resume feeding after a move.
- Often the only source of the strongest spotting, since heavy patterning is fully expressed in mature wild adults.
- Should be bought as fully quarantined, already-feeding adults, not as fresh imports.
F1 Rio Nanay
- Handles moderately harder tap water. Many keepers run F1 stock around pH 6.8–7.2 and 6–8 dGH without RO.
- Already conditioned to prepared foods, so feeding is straightforward from day one.
- More forgiving of a missed water change or a late filter cleaning.
- Still needs soft, acidic water to spawn reliably, even if it lives happily in harder water.
Be honest about which one you should own. Wild P. scalare is not a beginner fish. If this is your first angelfish, your first blackwater tank, or you do not own a TDS meter and a reliable low-range pH test, start with F1 stock or a hardier locality. Our Rio Nanay F1 angelfish listing exists for exactly that reason, and stock rotates as spawns grow out. The wild route is worth it when you already run stable soft water and want the adult fish with the pattern developed.
How to Tell a Real Rio Nanay — and Why the Market Gets This Wrong
A locality name adds money to a fish, and that is the whole problem. Because "Rio Nanay" sells for more than "wild scalare," the label gets attached to fish from other collection points, to mixed shipments never separated by locality, and sometimes to tank-bred crosses between locality forms that look roughly right and carry no locality integrity at all. Once two locality forms are crossed, the line cannot be un-crossed.
Before you buy, ask the seller these questions and expect specific answers:
- Wild-caught or captive-bred? If captive-bred, F1 from which wild parents, and were both parents from the Nanay?
- Which exporter and which collection point? A direct importer knows this; someone who bought from a wholesaler often does not.
- How long has the fish been in the country, and what quarantine and treatment has it had?
- Are the photos of the actual adult fish for sale, or generic stock images?
- If it is sold as an adult, is it eating prepared food, and what exactly?
Every fish we sell goes through a multi-week quarantine with prophylactic treatment for internal and external parasites, and we confirm it is feeding before it is offered for sale. We keep locality forms separate for the same reason — the Manacapuru, Santa Isabel, and Rio Negro scalare in the scalare category are distinct populations and are never mixed. The broader case for keeping wild genetics intact is in our article on wild-caught fish, genetics, and conservation, and the angelfish buyer’s guide covers vetting any online seller.
Water and Tank Setup
Height matters more than footprint for adult scalare. A 40-gallon breeder works for a proven pair; for a group of five or six grown out together, plan on 75 gallons or more with at least 20 inches of water column so adult finnage is never folded against the glass or substrate.
- Temperature: 82–86°F (28–30°C) for wild fish. Warm and stable, not fluctuating.
- pH: 5.0–6.5 for wild-caught, 6.0–7.2 for F1. Stability beats hitting a target number.
- Hardness: 0–3 dGH for wild-caught. This normally means RO or rainwater remineralized very lightly, not straight tap.
- Nitrate: under 20 ppm, under 10 ppm for breeding. Ammonia and nitrite at zero, always.
- Flow: gentle. Angelfish are ambush-oriented fish from slow, structured water, not a river current.
- Water changes: 30–50% weekly with temperature-matched, pH-matched water. Wild fish notice a mismatched change far more than F1 do.
Aquascape with vertical structure: driftwood branches, tall Amazon sword or vallisneria, and a bed of leaf litter. Botanicals are not decoration here — they release tannins that lower pH slowly and give shy wild fish sightlines to break. Our comparison of Indian almond leaves, alder cones, and catappa bark explains which ones do what, and the water parameters cheat sheet lists target ranges. Dim the lights or float plants; a bright, bare tank keeps wild angelfish permanently on edge.
Feeding
Wild Rio Nanay scalare are opportunistic micro-predators, taking insects, larvae, and small crustaceans in the river. Freshly imported wild fish often ignore flake and pellet at first, which is why we do not release a fish until it is confirmed eating.
- Frozen bloodworms, black mosquito larvae, brine shrimp, and mysis as the backbone.
- Live blackworms or daphnia to trigger feeding in a fish sulking after transport.
- A quality slow-sinking pellet once the fish accepts prepared food.
- Feed twice a day in small amounts. Uneaten food in a soft, acidic tank fouls water fast.
- Avoid a bloodworm-only diet long term — eagerly accepted, not complete nutrition.
Tankmates for a Single-River Biotope
Angelfish eat anything that fits in their mouth and get harassed by anything that nips long fins. That eliminates most nano fish and every barb with a reputation. What works is a community built on the same water chemistry and the same size class.
- Wild Rio Nanay green discus — same river, same water chemistry, a genuinely accurate biotope pairing with nothing compromised.
- Larger tetras such as rummynose or lemon, at an adult size the angelfish cannot swallow, in schools of 12 or more.
- Corydoras and other peaceful South American catfish, provided they tolerate the warmer end of the range.
- Dwarf cichlids such as apistogramma in a large enough tank, since they hold the substrate rather than the mid-water the angelfish claim.
- Avoid neon-sized tetras, shrimp, fin-nippers, and anything needing cooler or harder water.
Breeding and Pairing
You do not buy a pair of angelfish, you buy a group and let a pair form. Grow out five or six young fish together until two claim a vertical surface and start driving the others off it, then move that pair to its own tank — a spawning pair will hold territory across an entire community aquarium.
Wild Rio Nanay pairs spawn on vertical surfaces: a broad leaf, angled slate, a length of PVC. Eggs are laid in rows and both parents fan and guard them. Viable fry from wild stock generally require pH below 6.0 and hardness near zero, since eggs in harder water often fail to fertilize or fungus over. First and second spawns are commonly eaten, which is normal. F1 fish spawn on the same triggers but are less demanding about the numbers.
Unboxing and Acclimating Wild Fish After Overnight Shipping
We ship live fish from Philadelphia via FedEx Priority Overnight, UPS Next Day Air, and Southwest Cargo, to destinations across the United States and Puerto Rico, with free shipping on orders over $350 to the continental US. Transit is short, but it is still a stressful night for a wild fish, and the first hour after the box arrives determines a lot.
Our 100% Live Arrival Guarantee has one requirement worth reading before you open anything: if a fish arrives dead on arrival, you must photograph it in the unopened bag and send the photos within one hour of delivery to receive store credit. Shipping costs are non-refundable. So photograph first, open second — in that order, every time, even when the fish look fine.
- Have the tank cycled, heated, and parameter-matched before the fish ships, not on arrival day.
- Float the sealed bag 15–20 minutes with the tank lights off.
- Drip acclimate rather than pour. Transit water accumulates ammonia and drops in pH, and adding alkaline tank water abruptly is the classic way to shock a wild fish.
- Net the fish in and discard the bag water. Never pour shipping water into your system.
- Leave the lights off for the rest of the day and do not feed until the next morning.
- Quarantine arrivals separately for two to four weeks if you keep an established display — ours are treated on our end, but your biosecurity is your own.
Common Mistakes
- Buying wild before the tank is ready. Wild scalare do not forgive a cycling tank. Have it stable for weeks first.
- Chasing pH with chemicals. pH-down products in low-buffer water cause swings that kill faster than a stable pH of 7.0 would. Use RO and botanicals instead.
- Buying two fish and calling them a pair. Angelfish are not sold sexed for a reason. Grow out a group.
- Letting nitrate creep. The most common slow killer of wild angelfish is a tank that sits at 40 ppm and never gets a real water change.
- Trusting the label instead of the seller. Locality names are marketing unless someone can tell you where the fish was collected.
- Overstocking. Six adult angelfish in a 55 is not a group, it is a fight waiting for a spawn to start it.
If you are ready for wild stock, our fully quarantined Rio Nanay adults ship as feeding, treated adults with the spotting already developed. To compare locality forms first, the angelfish category lists what is currently available, and our Santa Isabel angelfish care guide covers a closely related wild form.