hi i recently purchased 2 swordtail fish at my local pet store. they've been fine up untill around 3 days ago. the female fish started hiding away in darkness and not eating, i do not know if she has been attacked or has a illness has the end of her dorsal fin + caudal fin has chunks out of it and now the male is hiding with her and he has like a white soar dorsal fin. my local pet store as tested my water today and said its spot on. any advice thanks