Zebra Danio, scale problems??

[Vikki.]

I'll try attach some pictures but basically one of my zebra danios' scales are sticking out near his tail and under his chin (best way i could describe it) and his gills are a darker red than usual.
I've only noticed this today but hes been getting lighter in colour the last few days. I was thinking dropsy but hes definately skinnier than usual - although hes been eating normally.
Maybe stress from the other fish?

Any help would be great so whatever it is can be treated.
Thanks guys!

 

[jpappy789]

Could you get some readings on ammonia, nitrite, and nitrate at the very least? Also a full stocklist and tank size would be great.

I do see what looks kinda like pine-coning but not at the typical "dropsy" stage.

 

[Vikki.]

its 180 litres with 6 zebra danios, 5 honey gouramis, 2 yoyo loaches and a common plec (who's hopefully being rehomed soon!)
I'm waiting on a new test kit to be delivered atm but the last test i did (about a week ago) was ammonia 0 nitrites 0 and nitrates around 30 but since then I added 3 of the gouramis.
I'll do a wc today and see how it goes.
I'm just hoping its not going to affect the other fish. Would it be worth putting him in qt or would that be too much stress and make him worse?
He's eating normally and hanging around with the other guys so no change in behaviour.

 

[Vikki.]

It might just be this one time but he's refused to eat. He came to the surface with all the others and even when i put a small bit of soaked flake in front of him he didn't eat it whereas normally he'd be biting my finger off :/
I've got a 15 litre qt ready, its got a small heater but no filter though, would that be okay if I kept on top of the WCs?
Also I've done a 30% wc on the main tank today.

 

[Vikki.]

He died jumped in the top of the filter (its one of the juwel ones that are attached to the corner of the tank)