Sagittarius is extremely important in regard to Pisces. And Apollo's Ascendant, Domicle-ruler of Sagittarius, is so closely tied to to its Regulating-ruler, Jupiter (as illustrated by the Olympiad Rings, with 2 of Jupiter's game-years on either side of Apollo's Pythian games), that I see Pisces as regulated by the Asc with a strong assist from Jupiter.
So, Pisces:
Domicile-ruler•••Neptune
Regulating-ruler•••Apollo's Triangle (visible portion of the Heavens, marked by the Asc first and foremost, as well as the M.C. and Desc.) + Jupiter as secondary Regulator
Motivating-ruler•••the Moon
Benefactory-ruler•••Venus
Exalted-ruler•••the Sun
Wow that’s interesting Jupiter sag and Pisces 🤔 there must be some real logic in this. In trad Jupiter is Pisces ruler anyway.
So when you look at Pisces in a chart you will look at alll the above mentioned eg Venus so what happens to Neptune with all these rulers etc.