South American Cichlids • GT hole in head?

[Boldingm]

Have a 100 gallon tank running 2 Fluval 407 canisters and a large sponge filter.
Water change done weekly atleast 50 percent half RO half tap .
Ammonia and nitrate levels always low to none tested with master kit ph kept at 7
Details out of the way my green terror may have hole in head if it is what should I do now .
I take pride in a clean healthy cycled tank and fish so I want to catch it and treat it now if possible .
Any input is appreciated thank you

[Auballagh]

Yes, it's possible your GT has a case of the dreaded disease..... But, I'm not completely sure that's what it is. All I can see is that one small spot, which could have been caused by mechanical injury in the aquarium. Have you had any problems in the past with your aquarium(s), and Hole In Head/HLLE disease?
And, have you actually tested and measured for Nitrates in your water? Typically, this disease is almost always associated with poor water quality. But from the weekly maintenance routine you describe, I'd say you're doing everything right to maintain high water quality in the tank.

[Boldingm]

The ammonia and nitrate never exceeds .25 and nitrate won’t exceed 5.0 ppm
Tested weekly before water change to make sure everything running smooth
Never had the issue before in smaller tanks I’m newer to cichlids so not sure.
But it seems to be a small pin hole kind of deep I noticed the spot before but at the time looked like a small scuff or scratch now it’s opened up.
Was thinking general cure with larger water changes with no carbon ,

[Auballagh]

All water conditions you describe for the aquarium sound good. And, since your GT is a young fish, it makes getting HiH/HLLE all the more unlikely. Do you typically use activated Carbon as part of the filtration media for your water? So anyway, if the fish has had this pinhole on his head for more than a few days, (not healing) it could be time to initiate treatment.
I like your plan to remove activated Carbon and conduct higher percentage water changes for the tank. Treating the tank with Metronizadole is typically done.
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And, is it possible to move your GT into a smaller quarantine tank? For a juvenile fish, something as small as a 20 gallon 'long' tank could work. But, placing your GT into a 30 to 40 gallon wide 'Breeder' tank might work best for this. If you can utilize a quarantine tank, the Metronizadole may be more effective, and you could also possibly administer Furan to prevent secondary infection. Provide established filtration, and a daily water change regimen of 80 to 90 percent are usually done with fish placed in smaller quarantine tanks. For longer quarantine periods, you may need to bump up the water temperature to around 80 degrees and treat with small doses of Epsom salt, (1 Tsp per gallon, is the recommended concentration).
Good luck with it, and I'm sorry to see anyone have to go through this.