Female Betta Fish With Red Spots In Fins

Hello I hace a sorority betta fish tank, they’ve all been in living in peace for one month approximately. Today I noticed that my alpha betta has some red spots in her fins, she didn’t had them yesterday, nor are they swollen and she has not changed her behavior or look sickI was wondering if you could help me to figure out what this must be, I’m worried it can be an infection.

 

Hi, can you please list ammonia, nitrite, and nitrate values? Just to rule out ammonia and nitrite poisoning.

 

Yes, my ammonia levels are below 0.02, nitrate 20 and nitrite 0, my water is very hard, because of the tap water conditions of where I live between 150-300 and Ph 8

 

Its naturaly coloration, two of my girls have it. White bettas can be marbled/koi so they can get random spots and specks of colors, including iridescent, red, blue, black...