Pterophyllum scalare — Angelfish

Species Overview

Pterophyllum scalare, commonly known as the freshwater angelfish, is a cichlid species native to the slow-moving, heavily vegetated blackwater rivers and floodplains of the Amazon Basin in Peru, Colombia, and Brazil. The genus Pterophyllum (Greek: “wing leaf”) includes three species: P. scalare, P. altum, and P. leopoldi. P. scalare is the most widely traded in the aquarium hobby due to its manageable size, elegant shape, and adaptability.

In nature, P. scalare forms loose schools and inhabits areas with dense root tangles and submerged vegetation, where it preys on small invertebrates, insect larvae, and fry. It exhibits a laterally compressed, disc-shaped body with elongated dorsal and anal fins, reaching up to 6 inches (15 cm) in body length and 8 inches (20 cm) in height (including fins).

Why it matters in the hobby: The angelfish is a cornerstone of the community aquarium, prized for its graceful movement and variety of captive-bred color morphs (e.g., marble, koi, black, platinum). Its semi-aggressive temperament and specific water requirements make it an excellent species for intermediate aquarists seeking to advance beyond beginner fish.

Tank Requirements

Minimum tank size: 30 gallons (114 liters) for a pair; 55 gallons (208 liters) for a group of 4–6 adults. A tall tank (height ≥ 18 inches / 45 cm) is strongly recommended to accommodate their vertical finnage.

Substrate

Fine sand or smooth, small-grained gravel is ideal. Avoid sharp substrates that can injure the delicate barbels or the ventral fins during bottom foraging.

Decor

Provide ample vertical structure: driftwood branches, Amazon sword plants (Echinodorus spp.), and floating plants (e.g., Salvinia, Limnobium) to diffuse light and create shaded zones. Angelfish are naturally shy and require hiding spots among plants or rock caves. Leave open swimming areas in the mid-to-upper water column.

Tank Mates

Compatible	Incompatible
Peaceful tetras (e.g., cardinal tetra, rummy-nose tetra)	Fin-nipping species (e.g., tiger barb, serpae tetra)
Small to medium corydoras catfish	Aggressive cichlids (e.g., oscar, Jack Dempsey)
Rasboras and dwarf gouramis	Very small fry (e.g., neon tetra) — may be eaten
Plecostomus (bristlenose, not common pleco)	Fast, boisterous swimmers (e.g., danios)

Important: Avoid keeping angelfish with any species small enough to fit in their mouth (≤1 inch / 2.5 cm). They are predatory cichlids and will eat fry or tiny tank mates.

Water Parameters

Parameter	Optimal Range	Notes
Temperature	76–82°F (24–28°C)	Stable temperature critical; avoid fluctuations >2°F/day
pH	6.0–7.5	Soft, acidic water preferred (pH 6.5–7.0 for breeding)
General Hardness (GH)	3–8 dGH	Soft to moderately hard
Carbonate Hardness (KH)	3–6 dKH	Buffers pH; avoid sudden drops
Ammonia (NH₃)	0 ppm	Highly toxic; must be undetectable
Nitrite (NO₂⁻)	0 ppm	Equally toxic; zero required
Nitrate (NO₃⁻)	<20 ppm	<10 ppm preferred for long-term health

Real values: In their natural Amazonian habitat, P. scalare encounters pH 5.5–6.5, GH 1–4 dGH, and temperatures of 78–84°F (25–29°C). Captive-bred specimens tolerate a wider range, but stable parameters are essential.

Filtration and Lighting

Filter Type

A canister filter or hang-on-back (HOB) filter rated for 2–3 times the tank volume is recommended. Use a pre-filter sponge on the intake to prevent fins from being sucked in — angelfish have long, delicate fins prone to injury.

Flow Preference

Low to moderate flow is ideal. Angelfish are not strong swimmers and prefer calm water. Use a spray bar or diffuser to break up strong currents. In nature, they inhabit slow-moving rivers and floodplain lakes with minimal flow.

Lighting

Moderate lighting (0.5–1 watt per gallon using LED) is sufficient. Avoid intense, direct light that causes stress and promotes algae. Floating plants like Limnobium laevigatum (Amazon frogbit) can help diffuse light and create shaded areas. A 6–8 hour photoperiod is recommended.

Diet and Nutrition

Staple food: High-quality cichlid pellets or flakes (e.g., Hikari Cichlid Gold, Omega One Cichlid Pellets) containing at least 35–40% protein. P. scalare is omnivorous with a carnivorous bias.

Treats

• Frozen or live brine shrimp (enriched with spirulina)
• Bloodworms (frozen or freeze-dried, pre-soaked to avoid bloat)
• Daphnia (live or frozen) — excellent for digestion
• Chopped earthworms (for adults, occasional)
• Spirulina-based wafers (for plant matter)

Feeding Frequency

Juveniles: 2–3 small meals per day. Adults: 1–2 meals per day. Fast one day per week to prevent digestive issues.

Portion Rule

Feed only what they can consume in 2–3 minutes per feeding. Overfeeding leads to obesity and water quality deterioration.

Supplements

Vitamin C: Supplementing with vitamin C (e.g., via Selcon or liquid vitamin additives) can boost immune function and reduce stress, especially during acclimation or after disease treatment. Add to frozen food once weekly.

Garlic extract: A natural appetite stimulant and antiparasitic agent. Use garlic-infused foods or additive (e.g., Garlic Guard) when fish are reluctant to eat or as a prophylactic against internal parasites.

Calcium and iodine: For breeding females, calcium supplementation (via cuttlebone or calcium-enriched pellets) supports egg development. Iodine is beneficial for thyroid function but rarely needed if a varied diet is provided.

Note: Most high-quality commercial foods already contain balanced vitamins. Supplements should be used sparingly and only when specific deficiencies are suspected.

Common Health Issues

1. Ich (White Spot Disease)

Symptoms: Small white cysts (like salt grains) on fins, body, and gills; flashing (rubbing against objects); rapid breathing. Treatment: Raise temperature gradually to 86°F (30°C) for 3–5 days (if fish can tolerate), add aquarium salt (1 tsp per 5 gallons), and use a formalin-malachite green medication (e.g., API Ich Cure). Ensure adequate aeration.

2. Fin Rot

Symptoms: Frayed, discolored fin edges with white or red margins; progressive fin erosion. Treatment: Improve water quality (perform 50% water change daily for 3 days). Use a broad-spectrum antibiotic like erythromycin or kanamycin for 7–10 days. Isolate severely affected fish.

3. Hole-in-the-Head Disease (Hexamita)

Symptoms: Small pits or erosions on the head and lateral line; loss of appetite; stringy white feces. Treatment: Metronidazole (oral or bath) combined with improved diet (add vitamins). Reduce stress and ensure pristine water conditions.

4. Dropsy

Symptoms: Severe abdominal swelling (pinecone-like scales protruding), lethargy, loss of buoyancy control. Treatment: Isolate immediately. Use Epsom salt baths (1 tbsp per 5 gallons) to reduce fluid retention. Antibiotics like nitrofurazone or kanamycin may help if caught early. Prognosis is poor.

5. Velvet Disease

Symptoms: Gold or rusty dust-like coating on skin, clamped fins, rapid breathing. Treatment: Dim lights (parasite is photosynthetic). Use copper-based medication (e.g., Coppersafe) or formalin baths. Raise temperature to 82°F (28°C) to accelerate parasite life cycle.

Beginner Mistakes

• Keeping angelfish in a tank that is too small or too short. A 10-gallon tank is insufficient; angelfish require vertical space for their fins and horizontal swimming room. Many beginners underestimate their adult size (6 inches body length).
• Mixing with fin-nipping or aggressive tank mates. Tiger barbs, serpae tetras, and bettas will damage the long fins, leading to stress and infection. Always research compatibility beforehand.
• Neglecting water quality and stability. Angelfish are sensitive to ammonia, nitrite, and rapid pH/temperature swings. Beginners often skip cycling the tank or perform infrequent water changes, resulting in disease outbreaks.
• Overfeeding or feeding an unbalanced diet. Feeding only flakes or overfeeding leads to obesity, bloat, and poor water conditions. A varied diet with high-quality pellets and frozen foods is essential.

FAQ

Can angelfish live alone?

While a single angelfish can survive alone, they are social cichlids that thrive in groups of 4–6. A lone individual may become timid or stressed. Pairs form naturally and breed readily.

How long do angelfish live?

With proper care, P. scalare can live 8–12 years in captivity. Lifespan is influenced by genetics, diet, and water quality.

Why is my angelfish hiding all the time?

Common causes: new environment (acclimation stress), aggressive tank mates, poor water parameters (high ammonia/nitrite), or lack of hiding spots. Ensure the tank is cycled, provide dense planting, and check compatibility.

Can angelfish breed in a community tank?

Yes, but success is low because other fish will eat the eggs and fry. For breeding, set up a dedicated 20-gallon tall tank with a slate or broad leaf (e.g., Amazon sword) as a spawning site. Maintain pH 6.5, temperature 80°F (27°C), and soft water.

What is the ideal tank shape for angelfish?

A tall, rectangular tank (height ≥ 18 inches) is ideal. Cube tanks (e.g., 24x24x24 inches) also work well. Avoid bow-front or narrow tanks that restrict vertical fin movement.

References