What’s the white specks?

[ADawson23]

Good evening, was doing a 40% water change this evening and noticed on my juvenile Raphael cat a bunch of little white specks, I did some more looking around and noticed on my erwini cat a white mark in the middle of his head. The two typically hang out together. Never witnessed any aggression between the two. They share a 220 gallon with (all fish are juveniles) 2 oscars, 1 common pleco, 1 bushy nose pleco. The two oscars came from petco. They were the first fish in the tank (2 weeks alone before adding new fish)

On Saturday my wife and I ventured to a LFS and picked up the 4 other fish (mentioned above) along with some new plants and a large piece of driftwood. I properly acclimated the new fish to the tank. Added the plants and driftwood while waiting to add the fish. Sunday evening I performed a 25% water change. Tuesday I noticed that one of the oscars appeared to be “gasping” so I checked my WC (api freshwater master kit) and ammonia was .25 plus or minus, nitrite 0 and nitrates 30 to 40ish. I did a 75% water change. This evening checked the parameters again and ammonia .10ish, nitrite 0 and nitrates.15. I did a 30% water change and that’s when I noticed the issues.

So my question is, should I be concerned and need to treat for anything, or am I just being overly dramatic lol.

 

[ADawson23]

Water conditions after the 75% change. This evening went ahead and did a 30% water change

 

[WOLF2013]

To me those white spots look normal on the rapheals and irwini. Armored catfish tend to have them. All the doradids I have kept have had that. Probably their slime coat or something. The niger catfish in my profile picture has some of the white specks.