McEve, what is the injury from, fighting? How large is the fish in the photo? Do you know the sex? Just in front of the dorsal seems to be where a male positions himself on the female during courtship.
Keep an eye on it and if it gets worse dilute ioding treatment directly to the fish sometimes does the trick.
Rehousing the group recently is the likely cause of the injury, there's likely to be a bit of infighting until things settle down.
Personally I think the fish should be ok providing a secondary infection doesn't set in but as you say the wound is still clean at the moment.
In a few days the redness of the wound should start to disapper as it begins to heal. If there is no improvement or you notice that it gets worse I would do as INXS has suggested.
I see you speak Swedish INXS Jod would probably be the right term here. That so dark red that it's almost black, and sting like h*** when applied? I remember we used it on horses...
She's not as red around the wound anymore, but now there's fungus on it. My eSHa better arrive soon...
24 hours later the red area has disappeared, but it's creeping up the first spine on her dorsal fin.
This is how she looks like after iodine treatment:
I'm worried about her (hmmm... him...? I never noticed how much odontodes the fish has before taking close up pics...) now. I'm unsure if I should have diluted the iodine? She moves around but doesn't look happy.
Should I repeat the treatment? And should I dilute the iodine?
I have a local fish group here in Inverness and the advice I got from the fish vet was to use malachite green for fungal infections and believe it or not to use mouth ulcer treatment with ADCORTYL on open wounds and infected areas as it contains an antibacterial antiseptic agent and will create a water resistant barrier over the wound.