I felt shy of asking about prostatic fluid from the Apostle ﷺ because of Fatimah. I, therefore, asked al-Miqdad (to ask on my behalf) and he asked. He (the Holy Prophet) said: Ablution is obligatory in such a case. (Using translation from Muslim 303b)  

أَنْ أَسْأَلَ النَّبِيَّ ﷺ عَنِ الْمَذْيِ مِنْ أَجْلِ فَاطِمَةَ فَأَمَرْتُ الْمِقْدَادَ فَسَأَلَهُ فَقَالَ «فِيهِ الْوُضُوءُ»