Koi Angelfish (Pterophyllum scalare) | Live Freshwater Semi-Aggressive Fish

The Koi Angelfish (Pterophyllum scalare) is a tank-bred color variant of the classic South American angelfish, prized for its calico-style splash of orange, black, and pearl-white on a tall, graceful body. Mature fish often develop more vivid orange "caps," making koi angels a centerpiece fish for the well-planted community tank. Care level is beginner-to-intermediate, temperament is semi-aggressive (cichlid). Browse the rest of our freshwater livestock and supplies.

Care Guide

• Tank size: 30 gallons minimum for a single juvenile; 55+ gallons for a pair, 75+ for a group of 4–6. Tall tanks suit their body shape best (18″+ height).
• Temperature: 76–82°F (24–28°C).
• pH: 6.5–7.5. Tolerates a wider range when acclimated slowly.
• Hardness: Soft to moderately hard, 3–15 dGH.
• Aquascape: Tall driftwood, broadleaf plants (Amazon Sword, Anubias), and open swimming lanes. Avoid spiky/sharp décor — long fins tear easily.
• Filtration & flow: Gentle flow. Strong currents stress them and shred their fins.
• Group dynamics: Best raised as a group of 6 juveniles, then thinned as a bonded pair forms. Solo adults are fine; single random pairs without prior bonding can fight.
• Feeding: High-quality flake or pellet 1–2× daily, supplemented with frozen bloodworms, brine shrimp, and daphnia. Avoid feeder fish (parasite risk).

Specifications

Compatibility

Temperament: Semi-aggressive — peaceful most of the time, but they are cichlids. Expect mild territorial behavior, and outright pair-bonding aggression once a couple forms. Long fins make them easy targets for fin-nippers.

Good tank mates:

• Larger peaceful tetras — Bleeding Heart Tetras, congo tetras, lemon tetras
• Bottom dwellers — Panda Corys, Orange Laser Corydoras, bristlenose plecos
• Mid-water dither — Zebra Danios (in larger tanks)
• South American dwarf cichlids — Bolivian Rams, apistogrammas

Avoid: Fin-nippers (tiger barbs, serpae tetras, some gouramis), very small tetras like neons (will be eaten once angels mature), aggressive cichlids, and dwarf shrimp (snack food).

Recommended Foods & Supplies

• Ocean Nutrition Brine Shrimp Plus Flake — high-protein staple, brings out koi coloration
• Seachem Prime — water conditioner for weekly water changes
• Browse all aquarium nutrition — frozen foods are essential for color and breeding condition
• Freshwater aquarium plants — tall plants like Amazon Sword complement their body shape
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Frequently Asked Questions

How big do Koi Angelfish get?
About 6 inches tall (top of dorsal to bottom of anal fin) and roughly 4 inches long, fully mature. Plan tank height accordingly.

Will the orange "koi" pattern fade as they grow?
The opposite — koi angelfish typically intensify as they mature. Young fish look pale; the bold orange caps and black-and-white marbling develop with age, good food, and stable water.

Can I keep just one?
Yes. Solo angels do fine. The complication is keeping multiple unrelated adults — pairs form unpredictably and can fight. Either keep a single fish, a confirmed bonded pair, or a group of 6+ raised together.

Are they hard to care for?
No — angelfish are a beginner-friendly cichlid, but they're sensitive to high nitrate and poor water quality. Weekly 25% water changes and a quality filter keep them thriving.