The Major Arcana Tarot Card allocated to the sign of Pisces is the Moon card. The general meaning of this card is subconscious realms, illusions, cycles & women’s cycles, changeability & unreliability.
The Minor Arcana Cards of the Eight, Nine and Ten of Cups have less obvious connections to the sign of Pisces. To begin with, each Suit corresponds to an element, and the Suit of Cups corresponds to the element of Water, the emotional plane. Since Pisces is a Water sign, it corresponding minor cards will be found in the Suit of Cups.
When a Decan Wheel is consulted (see image below), the first Decan of Pisces is found to correspond to the Eight of Cups, Lord of Abandoned Success (February 19 - February 28.) The second Decan corresponds to the Nine of Cups, Lord of Material Happiness, (February 20 - March 9). And the third Decan corresponds to the Ten of Cups, Lord of Perfected Success (March 10 - 19). If your Sun sign is Pisces, you can determine which minor card is “your” card by seeing where your birthday falls within the Decans, by consulting the chart below. It can be used as an alternate Identifier, or you may contemplate how the card is thematic in your life. Additionally, using the Decan Wheel allows for time to be introduced into readings.
What exactly is a Decan Wheel? A “Decan Wheel” divides a circle, which has 360 degrees, into 36 10-degree segments (“dec” means 10.) Each of these 36 segments correspond to one of the Minor Arcana cards in the Tarot, excluding the Aces and the Court Cards. The 36 segments are grouped into 12 groups of 3. The 12 groups are the Zodiac signs, and the 3 within those groups are the Cardinal (1st decan), Fixed (second decan) and Mutable (third decan) sub-aspects of each sign. So for example if your birthday is October 6, your birthday falls within the approximate 10- day segment of the 2nd decan of Libra. This indicates your birthday is a Fixed sub-aspect (the 2nd decan) of a Cardinal sign (Libra), and corresponds to the 3 of Swords. Reflecting on your particular set of aspect & correspondence will undoubtedly inspire insights about yourself and your life.
Sources:
Tarot Correspondences by T. Susan Chang
Tarot Deciphered by T. Susan Chang & MM Maleen
Qabalistic Tarot by Robert Wang