I can't tell very well there in the pic, other than it looks sore.
Keep the water quality perfect 0 ammonia, 0 nitrite and under 30 Nitrates and Keep doing
pwc very frequently, keeping the water as good as possible. If it looks worse in a day or so then it would mean medicated treatment.
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New to FW fish? First tank in a long time or EVER??? Need some info on keeping fish?

Start here - Aquarium Advice Article
https://www.aquariumadvice.com/guide...ater-aquarium/
FW Favorites right now Clown Loaches, any shrimp - SW Vase Red Mangroves