Kuhli loach with hole near gill

One of my kuhli loaches is sick and I genuinely have no idea what's wrong. This is my first tank I'm running by myself, he's only been in there a week, and any help you can give on whats wrong and how to help would be greatly appreciated. This started 1-2 days ago but the hole is very recent.

Tank size: 200L (50 g)
tank age: 3 months
pH: 7.2
ammonia: 0.25
nitrite: 0
nitrate: 0
kH: 53 ppm
gH: ?
tank temp: 25°C


Fish Symptoms: heavy breathing for a while now very slow breathing, originally swimming really fast in a circle then staying still in the open, now just lying on the ground breathing shallowly, has skin peeling near gill and a hole on one side.

Volume and Frequency of water changes: 1-2 times a week 20 to 40 percent, 50 percent once a month

Chemical Additives or Media in your tank: log, some rocks, gravel, pink baby tears, ambulia, swords, adding water conditioner after water changes, adding liquid carbon every other day.

Tank inhabitants: 5 kuhli loaches, 10 cardinal tetras, 2 Pakistani loaches, 1 bristlenose, 2 corys, 1 rummy-nose, 1 tetra of some description, and a mild snail infestation.

Recent additions to your tank: the kuhlis, Pakistani loaches, and the cardinals have only been in there for a week.

 

Looks like the problem might be a bacterial ulcer. Unfortunately the prognosis isn't very good.
Loaches usually don't do well with meds.
You might try a botanical such as Microbe lift Artemiss.

 

Looks like the problem might be a bacterial ulcer. Unfortunately the prognosis isn't very good.
Loaches usually don't do well with meds.
You might try a botanical such as Microbe lift Artemiss.

Could it hurt my other fish? Like is it contagious or anything?

Thanks for your response btw, even if it dies its good to know why.

 

The tankmates are probably okay.
Don't allow them to graze on an infected corpse.

 

The tankmates are probably okay.
Don't allow them to graze on an infected corpse.

Ok thank you so much for your help!