Fish wound

Question
I've had my 40gal tank cycled for 4 months, the tank for 5.
I have 4 goldfish, 2 pearlscales & 2 black moor.
I use an Aquaclear 50 filter.
pH is 6.9, ammonia is .00, nitrites 0.0, nitrates 2.0ppm
I change 35%(15gal) of the water about once every 10 days.
__________________________________

My fish seems to have developed a wound. It's not open or bleeding, but it looks quite painful and my poor fish looks almost like hes suffering from mild swim bladder trouble too (cant seem to fight a very small current, going bottom up (not belly up) ). I've linked some pictures, and I'm wondering if it looks like my pleco has been snacking on this poor fish at night or something. None of the other fish have any sores or troubles, just this pearlscale. I've added melafix to the water along with a fresh 35% water change and salt (1tbsp per 5 gal) & taken the pleco out of the tank just in case and put him in my roommates tank. Please let me know what you think could've caused this and what else I can do for him!!!

Answer
Hi Kerry;

I answered your question on the one with the photo links, but just thought of something else too. It's possible the pleco has been sucking him and the area became infected. Goldfish put out more slime than other fish do and plecos as well as other suckerfish sometimes like to eat it. (Yuck) Moving him was a good idea for now. It might be nothing, but then again...you never know.

Melafix and salt are very good to use right now, but as you will read in my other answer he probably needs more. Keep up with the diligent work, read my other answer and hopefully he will feel better soon.

At Your Service;
Chris Robbins