Panda Corycat Horns?

Hi, I've had my panda cory for almost a year now he spent most of his life in a 9 gallon, where he wasn't very active, due to some weird urgent disease that wiped out all of my tetras with perfect water parameters and melafix doing nothing, I moved him and the couple other cory cats I had into a 15 gallon tank, he still isn't super active, but he's growing what looks to be horns, or like whiskers on his forehead, it's kind of concerning and I'm worried it may be fungus, or it could be natural growth but I cannot find anything on the internet about it. I took a couple of pictures, again I am aware they're not in idea substrate but they don't often have to go far to find food as I place it close by. Again I just want to check if it's parasitic I am treating them all with it as a precautionary as the other tank became better after treatments, but if it's fungal I honestly, do not know how to treat it.

Those are his nostrils totally normal and healthy. They have a tube extension nostril and a hole nostril, that's normal for corydoras.

However, there is a bit of erosion around them, which can be due to bacteria. Should have sand substrate instead of gravel as he won't dig as hard into it to reach food that falls into it, this can lead to infections on their face area and prohibits them from sifting which is a natural behavior for them.

Do a good water change, keep nitrates below 20ppm, and don't bother with melafix (it's useless)

The aquarium water looks a little milky cloudy. If this is the case, check the ammonia and nitrite levels, and do a 75% water change and gravel clean the substrate every day for a week.

What sort of filter is on the aquarium?
How often and how do you clean the filter?

Melafix has a proven antibacterial ingredient, but the concentration of the ingredient is so low it won't do much. It's almost homeopathic, and useless.

I agree with @CassCats , but the nostril extensions are extra large. They may have been injured, but pose no danger. To me, they look like the Cory version of a fighter's cauliflower ears.