Pisces is made up by two separate entities, which, in their animal form, are huge sea creatures resembling fishes with elongated bodies similar to those of eels. Their general look is vaguely reminiscent of koi fish. The two of them appear from an ethereal vortex generated behind the one employing their key. Both share similar traits, possessing large, wide, open, and round eyes with dark pupils sitting at their heads' sides, and massive mouths with light, thick lips full of squared teeth. A number of fins are also present on their bodies, with a series of long, jagged ones crossing the whole length of their upper part, almost reaching up to the top of their heads, and a smaller, more squared fin located on the ends of their faces, one on each side. Their bodies are covered in lines crossing their whole length, with each line being flanked by a row of spots; more spots form a single, hinted semicircle above each eye. What distinguishes the two fish is the color: the one to the right from the portal is light and sports dark markings; the other one, on the contrary, has light markings covering its dark body. Both creatures bear the symbol associated with the constellation of Pisces on their forehead, respectively dark and light in color.
As Yukino later reveals, the Celestial Spirit's true, humanoid form is that of a mother (the light fish) and her son (the dark one). The former is a slim young woman of average height possessing long, straight and glossy dark hair, reaching down to her middle back, which is gathered above her forehead in a prominent front bun, but is left to freely flow backwards on her shoulders in two strands. She possesses slanted dark eyes, each linked to the corresponding side of her face by a linear tattoo which forks in proximity to the eye, and two dark protrusions reminiscent of membranous fins sit at her head's sides. Hers is a very curvaceous figure, with her ample breasts being hugged and partially exposed by a revealing top made of massive light scales, going from her waist to her neck while baring the central part of her torso, with shoulder pads extending on her shoulders. The woman's arms are covered by light-edged dark sleeves adorned by intricate, light decorative motifs; these very same motifs are present on her full-length, mildly loose matching pants, while her feet are covered by plain, dark open top shoes. Her forehead is adorned by a light, simple crown, bearing a massive light gem on the front. Loke, someone known for dating extremely attractive girls, went on to praise her beauty, noting how it "makes you forget she has a child". The son, on the other hand, possesses an inverted colorscheme, with his dark-skinned, toned and muscular body creating a contrast with his extremely spiky light hair, just a bit shorter than his mother's, with spikes jutting outwards even on top of his head, and a pair of short strands framing his forehead. He shares the woman's tattoos, fins and crown (which, however, true to the inverted colors, bears a dark gem), but also sports an earring shaped like a shell on each ear, and a light necklace with a similarly shaped (though larger) pendant hanging from it; he, too, wears an indument made of scales, this being a massive belt which extends downwards on his legs' sides to cover the lower part of his loose dark pants. A massive, dark ribbon is tied diagonally on the left part of his chest, going above his left shoulder in close proximity to his neck, around his wrists are massive dark bracelets with light edges (the left one of which is paired with some bandages going up the corresponding arm), and yet another bracelet, adorned by a series of dark and light triangles, is found on the boy's left bicep. Pisces' male form carries around a polearm in his right hand, this having its upper, offensive edge shaped like the Celestial Spirit's symbol.
Should the two beings come in contact with water while in their humanoid form, they'd be turned into a much smaller version of their animal form as a result.
While Pisces are in their human form, the son seems to have a comedic habit, using "mom" to refer to not only his mother, but also those who summoned the two of them, much to the amusement of his parent.
While Pisces are in their fish form, they appear to be quite eccentric, shouting "gyu gyu" often.
Water Magic: While in human form, Pisces use Water Magic as their primary source of combat. The mother employs this Magic as a Caster type, being able to create masses of water accompanying her motions when she kicks in order to increase the damage inflicted to the target via the blunt force of the liquid. On the other hand, the son uses it as a Holder Magic, wielding a trident to send waves focused around the weapon's tip against the opponent when he lunges at them. However, both can combine their Magic to create powerful beams of water.
Flight: While in fish form, Pisces can glide through the air and attack their opponents from above. Their main form of offense seems to consist of throwing themselves against the target at high speed, using their massive heads to inflict powerful blows. Such a rudimentary attack possesses enough force to raise large amounts of sand into the air, when the fish's strikes connect with a sandy surface. The two separate beings are capable of synchronizing their assaults, moving in unison.
Melee Combatant: While in their human form, Pisces have been shown to use melee combat techniques which come enhanced with Water Magic as their means of fighting. Their split nature allows them to combine their assaults, making them harder to avoid.
- Hand-to-Hand Combatant: Mother Pisces fights unarmed, and could pull a water-cloaked crescent kick with high precision.
- Spearmanship: Son Pisces has been shown handling his trident skillfully, landing quite a devastating water-imbued strike through its use.
Immortality: As a Celestial Spirit, Pisces cannot die, unless they are somehow forced to stay in the Human World for a long period of time.
Trident: While in their human form, the son carries a long trident with him. In its posterior part, it has an adorned fish scale in the edge, while an eel-like garnish rolls around the handle. In the anterior part, the trident is featured as a plated Pisces' sign, that's compressed with salient borders and has two dots in its lower parts. The trident is used by the son to cast Water Magic spells, surrounding it with streams of water and directing it at the target.