Aquarius resembles a royal blue mermaid. She has a long, blue fish-tail, light blue hair that reaches up to her waist, curvy, and a large bust. She has blue eyes that seems to have no pupils. Aquarius wears a dark blue bikini top and on each arm, she has a golden armlet and bracelet. Aquarius also has a headband, three piercings on her tail, and a golden belt at her waist. A dark blue tattoo resembling the Aquarius zodiac symbol rests right under her collarbone. Aquarius also wields an urn that acts as the basis of the Water Magic she employs in battle. This design reflects her respective zodiac sign; "Aquarius" is often depicted as a merman or mermaid carrying a vessel from which a pouring stream of water emerges.
Aquarius is a moody and ill-tempered Celestial Spirit who often threatens to kill her owner, Lucy. While other Celestial Spirits serve Lucy obediently, Aquarius is irritated by her. When summoned, Aquarius will either attack the opponent, Lucy, or both of them, depending on her mood. Despite this, Aquarius does care for Lucy's well-being. She is very kind and loving towards her boyfriend, Scorpio, to whom she shows a completely different side of herself. Additionally, she threatens Lucy to keep quiet about her moodiness in front of Scorpio lest Lucy become a "drowned corpse." When Lucy is in her presence, Aquarius tends to make remarks about having a boyfriend since Lucy doesn't have one. As time progresses, however, Aquarius' attitude toward Lucy becomes more lenient and compassionate.
Water Magic: Aquarius uses Water Magic as her primary source of combat. Using her Magic, she is able to control water through her urn to hit opponents with great force, usually done via giant waves of water or through variations of beam attacks. She is a powerful Celestial Spirit; even after Loke, a "combat specialist", became one of Lucy Heartfilia's Celestial Spirits, Lucy considers Aquarius as strong as him or possibly even above his level of strength.
- Bubble Shot: A stream of big bubbles are released from Aquarius's urn, which hit the opponent with great force, multiple times.
- Water Pillar: Aquarius swings her urn towards the target creating a huge pillar of water that strikes the target from below.
Levitation: Aquarius can float in the air.
Immortality: As a Celestial Spirit, Aquarius cannot die unless she is somehow forced to stay in the Human World.