Skin problem?

Dear Dirk
Could you please help me with the following discus problem?
This has been for a week but only just seen black spots today, none of the other fish have any symptoms. He is at the bottom of the pecking order and is being bullied alot.
I have attached photos (hope this helps)
I would appreciate your assistance.

Kind regards,

Jane

Where do you stay?: Cape Town
How long have you been keeping tropical fishes?: 3years
How long have you been keeping discus? Are these the first discus you keep? Almost one year
Description of the sick fish (age, size, breathing speed): 11cm, breathing normally
Describe the problem that the fish is having: (behaviour, breathing, excretion (droppings), food intake, colour): Scratches sometimes, droppings look normal, eating normally
Has the problem occurred before?: No
Have you treated the problem and how?: Dosed with salt
Have you had any other problems in the past? What were they? Did you treat for these problems? How? Yes, Flagelletes, treated with metro
When and where did you buy these fishes from and what size were they when you bought them?: 5cm Lps
What type of discus are these? Wild or hybrid and which type?:
Your aquarium (Size; what do you have in the aquarium such as logs, stones; plants; gravel; fertilizer use; CO2? etc.): 1.5m, wood, sword plants, stone, poolfilter gravel
Your filtration (Type and size of filter, what is in your filter, liters per hour) sump,
Aquarium hygiene: (how do you clean your aquarium and your filter, how often do you clean your filter, when last did you clean your filter, when last did you clean your gravel?) 25% twice a week, vacum everyday,
How many fishes do you have in your tank (discus, their size and other fishes): 7 discus, ranging from 10cm - 14cm, 6 rummynose, 5 cardinals, 2 bn ancistrus
When did you last buy any new fishes and from where were they bought?: Havent
Which food are you feeding and how often do you feed? feed 4x day, granules, flakes, brineshrimp
Water changes? How often, how much, what is the temperature of the water you use for water changes, what is the source of the water (tapwater, well water, borehole water, river water) :tap water aged, and heated
Do you prepare your water for water changes? Reverse osmosis, peat filtration, do you add peat extract?: no
Water description (smell and colour): clear and normal smell
Water parameters in your aquarium
Temperature of the water: 29/30
General hardness (GH):
Carobonate hardness (KH):
Nitrite (No2-):0
Nitrate (No3-):20
pH-value and how did you measure your pH: 6.5 Sera Liquid

 

Hi Jane,

These symptoms are not the result of disease but are the result of the wounds and damage that the other fishes are causing to the fish. The area where the marks are are exactly where fishes would bash with their mouths into other fishes. Other than putting this fish into another tank where he/she gets away from the other bullying fishes, there is nothing else that you can do. This should also not need treatment as discus heal very well after wounding, but you must realize that he/she is being bruised by the other fishes on an ongoing basis and this is not good in the long run.

On all the other conditions you are doing things perfectly correctly and the reason why this fish has not lost more condition and suffered more because of the bullying is because you are looking after your fishes so well.

Kind regards,

Dirk

 

Hi Prof,

Thank you so much for your help, I will have to consider what to do, because the pecking order changes from day to day and I couldnt keep him by himself.
Have a lovely weekend.
Kind regards
Jane