Whats wrong with my fish? Picture included

[Ender024]

Hello, Ive had this pangasius sutchi for around 10years. Recently this abrasion that has developed on top of it hasnt gotten any better or healed. At first I chalked it up to it ran into something again as it has a tendency to do but it isn't healing. Can someone identify what the problem is by looking at the picture included and tell me what I need to do to fix it?
Sorry about picture quality

Water temp 78 degrees
150 gallons
4 angel fish
dozen minnows
6 tiger barbs
p sutchi 15"

fresh water

been up for 10 or more years

no live plants

eheim cannister filter, recently cleaned, not sure the gph but its more than adequate

some natural light

substrate recently vaccuumed, all the other fish are ok

hikari pellets as food

no unusual behavior

 

[convict360]

Need a better pic bro, have you checked all your water parameters?

Wild guess might be from overzealous canister cleaning, killing filter bacteria and crashing cycle, in which case ammonia and nitrites may be wreaking havoc on him. But that's just a supposition, will get a better idea from the test results

 

[Ender024]

Alright, I won't be around the tank till Saturday and ill bump this then when i can give an update and better picture

 

[convict360]

Alright, I won't be around the tank till Saturday and ill bump this then when i can give an update and better picture

Cool, was going to say water changes would be advisable until the pics arrive; but I'm assuming if you're away from the tank, no-one would be able to do that for you

 

[Ender024]

 

[Ender024]

In the last picture you can see something beginning to form on the gill. Please help, I've had this guy since he was an inch long fish in a walmart tank 10 years ago and have recently found a fish store to take him in, I just need to get him healthy

 

[convict360]

Aquanero