Should I be worried about the white pimple on my A. borellii?

[flori]

My Apistogramma borellii male has this white thing on his back, right next / at the lower end of his dorsal fin.

It looks like the "white head" of a pimple minus the red, swollen area of a human's pimple.

To me in person it looks less fluffy than it does in the pictures, but I'm not sure who's "wrong", me or the camera.

The tank is 23 gal, with him and a female plus 12 Paracheirodon simulans.
The values are:
ph 6.4
gh 4
kh 3
EC Tds 128
No2 0
No3 10
Temp 77F

My best bet (which isn't worth much) whould be he cut himself chasing the female around and has some fungus there now?

What else could it be and should I do anything other than regular water changes?

 

[Mike Wise]

I can't see the damage well enough in the photos. It might be a damaged scale or lymphocystis, a viral infection that generally clears up with top notch water quality and nutrition. Antibiotics don't work on viral infections.

 

[flori]

I can't see the damage well enough in the photos. It might be a damaged scale or lymphocystis, a viral infection that generally clears up with top notch water quality and nutrition. Antibiotics don't work on viral infections.

Unfortunately I couldn't get a better picture of it. There's no other spots like that and nothing on any other fish, and I think it got a bit smaller. Since the fish is behaving normally I'll just assume it's a damaged scale or other small injury for now, keep up the water hygiene and feed him lots of fresh brine shrimps which he loves, as all fish seem to do