Right pelvic fin does not fully extend down- mutation or will it heal?

[Trever]

I have a pair of bicolors I've had for 3 1/2 months.

Both are outwardly extremely healthy, good eaters, well paired in their own FOWLR tank, etc.

Yesterday I noticed the smaller one's right pelvic fin does not ever fully extend down from her body. It extends down partially. The length is fine, it just never seems to fully fan out and down the way the left one does.

I don't see any damage to the fin.

She swims fine AFAICT.

I reinstalled an egg crate partition to separate them, but after 24 hours, the fin seems unchanged. Usually nipped fins heal overnight.

I'm not sure if the fin is damaged or if the fin has always been this way and I just noticed. I am very attentive, so it seems unlikely I would not have noticed this (attentive but bad memory!).

I'll keep them separated for another day, but wondering if anyone has any relevant knowledge. Maybe these fins take longer to heal, maybe something like this happens and nothing to intervene about because it will always be that way, I don't know- any clues?

 

[Billldg]

It could be almost anything. Birth defect, injury, and so on. In all likelihood, it will not change. If its a injury, it may have just healed back that way, and if its a birth defect, then the same result. I have a Achilles tang with a left pectoral fin blemish. It works fine, but I know it will never change. I over look such small imperfections if the fish is healthy. I, and I am sure you are the same, love the fish the same no matter the imperfections. Its easy for me to see that my Achilles tang pectoral fin will not change as the fin is translucent and I can see the cartilage in the fin has grown to the imperfection, if that makes since. Not sure if you can see the same on a Bi-color as I have never owned one.