The trouble is avoidance, not conflict
Every sign at a hard angle to Pisces is mutable, and so is Pisces. That gives these combinations a distinctive shape: nobody stands their ground long enough to have the argument. Positions shift, the subject moves, and the disagreement survives in a new costume rather than being settled.
This is a genuine difficulty and it is nothing like the deadlock described between fixed signs. It is also badly served by the word worst, which implies a collision that in this case never quite happens.
The three angles named
Virgo lies 180 degrees from Pisces. Gemini and Sagittarius lie 90 degrees away on either side. No other sign forms a hard aspect to Pisces, so the list is fixed at three.
Virgo and Gemini belong to Mercury; Sagittarius shares Jupiter with Pisces in the classical scheme. The recurring complaint against Pisces from all three is the same one, phrased differently: that a thing was left unspecified when it could have been stated.
Virgo across the axis
The Pisces and Virgo axis divides one subject between correction and acceptance, sorting and letting be. The tradition has always read an opposition as attraction at least as readily as conflict, since the two signs share a mode and want the same ground from opposite ends.
Read that way, Virgo is the classic complement to Pisces rather than its opponent. Which of the two readings applies to a particular couple is not something an angle determines.
What a comparison actually finds
Squares are 90 degrees between signs of one mode and unlike elements, and how hard they bite depends on how close they are. Sun signs contain no such precision, so any list built from birth months is guessing at severity.
The contacts that matter are Saturn from one chart on the other's Moon or Venus, felt as warmth rationed; Neptune on a personal planet, which for a Pisces comparison is the one to watch, since it describes two people who have understood the same conversation differently; and hard Mars aspects, which describe how a quarrel escalates. The synastry calculator reads the real angles from two birth times, and synastry sets out the method.
The pairing over the ranking
The Pisces and Virgo page describes what the two accomplish and where they wear each other down, which is information a list position cannot carry.
Where both birth times are available the charts answer better than the sun signs did, in either direction.
Questions people ask about this
Which signs are difficult for Pisces?
Virgo opposite, Gemini and Sagittarius square. All three are mutable, as Pisces is.
Is Virgo a bad match for Pisces?
Not by the angle. The two divide one subject between correction and acceptance, and the tradition reads the axis as complementary as often as conflicting.
What is distinctive about mutable friction?
The disagreement is avoided rather than fought: positions shift and the subject is never settled.
Which contact matters most in a Pisces comparison?
Neptune on a personal planet, since it describes two people understanding the same exchange differently.