concerned for gourami

[Jennifer]

My blood red/flame gouarmi has a dark, dark blue line from his anus down his pelvic/anal fin...not on his body, on his fin only. I don't remember him having that blue line or seeing one starting and I wonder if his belly/chest is turning blue also (however i always doubt myself though when I think a fish is getting sick...I think his belly/chest has always been a silvery/blue colour and his dorsal fin is a shimery dark blue so I was wondering if its possible he's just getting more colouring on his other fin). He doesn't appear to be in distress and doesn't show any other symptoms of a bacteria/fungus disease. He is eating well and is still happily swimming around, tending to his bubble nest.

I am still concerned though because I have always had trouble diagnosing fish illness before its too late...now I am paranoid. So if anyone thinks the above sounds like the beginning of an illness let me know asap so I can treat!!!

thanks