Freshwater Angelfish (Pterophyllum scalare)

Angelfish are cichlids wearing a disguise — that tall, laterally flattened body shape is built for slipping between root systems and dense vegetation in slow-moving Amazonian water, not for open-water speed, and it's exactly why they look so striking gliding through a well-planted tank. They'll pair off on their own given the chance, and a bonded pair will pick a broad leaf or flat surface to guard fiercely once they start spawning, a genuine window into cichlid parenting behavior in an otherwise peaceful community fish. Their patience runs out with anything that nips fins, and their mouths eventually grow large enough to consider very small fish a meal, so stock tankmates with their adult size in mind, not their size on day one.