Opaline Gourami Skin Problem

Hi - My Opaline Gouramis are having problems recently and struggling to find out what to do. Going to try and put as much details on here as possible and see if anyone has any ideas... The tank has been set up for 1.5 years and I have had the gouramis for about 1 year - they have been fine until now.


Tank size: 140 Litres
pH: 7.2
ammonia: 0
nitrite: 0
nitrate: 40 mg/l
kH: 5d
gH: 20d
tank temp: 26
External filter
Airstone
Lots of real plants

Fish Symptoms (include full description including lesion, color, location, fish behavior):

Male Gourami has "flaky skin" is the best I can describe it - it started as patches around its head, but seems to be spreading. The area is discouloured (see pic later) and I can see bits falling off.


Volume and Frequency of water changes: I change water about every 2-3 weeks and last did a change yesterday (about 1/3rd)


Chemical Additives or Media in your tank:

Only really water conditioner for when I do the changes


Tank inhabitants: 6 Zebra danio, 6 zebra loaches, 1 flying fox, 5 neon tetras, 2 black neons & the 2 Opaline Gourami's

Recent additions to your tank (living or decoration): Nowt

Exposure to chemicals: Nowt

Digital photo is attached



The photo looks like its covered in something but it isn't - its not fungus - not sure what to do really.

All the other fish seem to be ok except the other gourami which has a redish "bloody" spot on one side near its tail - it looks as tho its cut itself on a rock - not sure if thats related really.

The ill one just seems to rock backwards and forwards near the top of the tank unless its feeding time - where he just acts normal and feeds well.

Anyone any ideas at all?

Peeling skin can be a numbers of things from bad water quality, parasites to bacterial.
Can't see the pic to be honest the head regions is the patch white with any red in it.
The sore on the tail will need a bacterial med.
Anys signs of flicking and rubbing.