2 Issues In Brackish Puffer Tank

So Squiry, my orange saddleback has been acting "off" a few days now, not eatting, and has this "dry skin" looking patch on his upper lip.
Hes still active, but is towards the top of the tank more then normal.
While I've been trying to figure that out, today I came home and found my smaller green chromid like this...
I'm Not sure what the white Mark's are.


Stats...
40b
Waterchange 10-20 gallons a week
Numbers 0,0,10
Is cycled (finally)
2 orange saddleback puffers
2 green chromids
Some guppies the puffers haven't eatten


I'm trying to upload a video

 

Do you know your salinity level ..
Although nitrates seem fine and I am sure cycled finally your not looking to hear about water changes but I can't imagine less then 50% 2X a week with the two puffs in a 40b?
You are shaking the bottles and everything like directions say for the nitrate test ??Many who don't shake get zero so 5 sounds close [sorry to sound or repeat stupid stuff] .
How about carbon ?
Is there room for a large amount of carbon somewhere in filter in leu of water changes ?
You see no aggression between puffs and chromids ?

 

No 0 aggression between the 2, the chromadis have a bit between themselves, I added some carbon to the filter 2 days ago, the algie bloom is killen me, I hate cloudy water.
My salinity I keep at about 1.012 and tank is at 78°.
Ya I shake all the bottles ALOT because I've read everyone's horror stories

 

Oh I also run a hob AND sponge filter in the tank

 

How is Squiry doing?

 

How is Squiry doing?

 

? What happened?

Is Squiry the same fish as Squirt? If so then I know what happened...

 

Yes he is

 

Ooooh ok. I thought maybe you had another one. Sorry for bringing it up again.