Featherfin Catfish - Bright White Marks And Lethargic

[testingtesting123]

Hi,
Since moving home recently my 6" featherfin catfish (synodontis eupterus) has had got some strange white blotches on his right side. I don't know if he's got agitated and cut himself against some rocks, but the marks seem to be getting worse not better.
He's not eating normally and not coming out from his hiding place in the evening as usual. I've not found anything similar googling, anybody come across this or got any idea what it is and how to fix it?
He's in a 36" tank (too small I know, I'm planning on a far bigger one soon, missus permitting) with 3 small clown loaches, 1 golden sucking loach, 4 small corys, a small redfin shark and more guppies than I remember buying. I'm in the UK and water quality's OK, I did a 90% water change last week when moving house.
The picture quality's not great as the photos were taken on my dodgy camera phone. The biggest mark looks like a reflection, but it's not.

Thanks in advance,
Dave

 

[WILDER]

Size of tank in gallons or litres.
Water stats in ammonia,nitrite,nitrate,and ph.
Sharp ornaments sand the sharp edges down with sand paper, then rinse the ornament under the tap.
Any signs of flicking and rubbing.
White marks like that can be bacterial to parasite, but usually bacterial.

 

[testingtesting123]

The tank is 28 gallons according to a calculator I just found on the net. pH is around 7 and I haven't got the kit to test for ammonia, nitrite, nitrate (just moved house, not had chance to buy yet). No problems with any other fish. Nothing with particularly sharp edges, no more so than normal rocks.
No flicking or rubbing.
Any idea what bacteria can cause this and how to treat it?
Thanks for the quick reply!

 

[WILDER]

The tanks overstocked.
Take a sample of your water to the lfs and tell them to write the readings down for you.
Overstocked tanks cause stress and ill health.
I would add a bacterial med to the tank.

 

[testingtesting123]

Just in case anybody happens upon this - these white marks were actually due to him burning himself on the heater!
I've now moved the heater, the marks have now healed and he's doing fine...

 

[WILDER]

Thats good news.
Thanks for the update.