Broken fish :C

I bought an Oranda last week, they separated him in the pet shop for me until yesterday, when I decided to go get him.
Either way, the first time I saw this fish, he was perfectly healthy and active and the tank they put him in was empty. But yesterday as I took him home, there were some small koi in the tank, and my poor Oranda had his dorsal torn to pieces, clamped close against his back and he was swimming rather slowly. I took him home (since I thought that it would get better as soon as he'd get out of there), and put him in my quarantine tank with some salt and medication against bacterial infection in case he'd have fin rot or any other infections because of his injuries. I'll be looking for some medicated food as well, but if this fish's gonna kick the bucket because of the people in that pet shop, they're gonna get a piece of my mind (and get him replaced) :C

I started looking at him, and noticed several abnormal swellings, two bigger ones on the sides of him and one smaller by the throat. I also saw that his caudal was torn as well. (In other words, I'm angry.)
This little fish of mine is rather hovering with head up, or head down by the bottom. Looks like he's struggling pretty much with anything he does.

I'll come back with my water parameters as soon as I'll get to testing it, but tell me what these swellings (and all the rest) are about! I don't think they are tumors or lymphocystis. I'd be happy about every piece of advice you've got.

 

Just wanted to add that the quarantine tank is 8 gallons, with sponge filter and an air stone.

 

Update: I tested the water chemistry, and it's flawless.
pH: 7.0
ammonia: 0
nitrite: 0
nitrate: 0

I popped down a few small pieces of tubifex for him, and he ate like he hasn't seen food in days!
I also discovered a few (like three) smaller black spots on his skin, might be some blackening due to healing. I'm pretty sure those koi he was introduced to weren't treating him too well.

(Sorry about the multiple posts, but there doesn't seem to be any "edit" button available as of now )

 

Alright, so it's a bacterial medication, containing a bit of methylene blue, acriflavine and phenylglycol. It is mainly for mouth-, fin rot and different bacterial infections. So yes, it's a liquid medicine. It should be dosed at a rate of 1ml per 20 liters of water every second day.

He seems to be alright at times as he's swimming about for a short while, but most of the time he's just crashed with the nose against the bottom, with barely any gill movements. Is it possible that it's too late?

 

That's exactly what I've been doing, how nice to have a confirmation at least! :'D
I've fed him twice with some freeze-dried tubifex, soaked before-hand so they'd be easier for him to eat.
Thank you so much for your advice, I'll be posting updates

 

I've been observing the fish all day, and he just seems to be getting worse... I honestly don't think that he'll make it 'til morning, but I'll be keeping my hope, and if he'll still be breathing by then, I'll add the second dose of meds

 

He died this morning, I found him with red chest, so he probably had some internal infections to boot...

Dawn:: Yes, I was thinking about that! And I'll be going there next Wednesday/Thursday sometime. Hopefully I'll get something back. Thanks for the advice though

 

Thank you, it's very nice to hear c':

 

Arr, he's buried already :'c Isn't it enough with another person as a witness maybe?
And, I actually don't think they're very professional in that shop... they don't seem to care much for the fish somehow. Which is the main reason I want to save the prettiest ones :'D

 

Ah, yes, I know a few people around forums and whatnot that have exactly the same thing In fact, I heard a sweet story from a friend that a person at a pet shop told her This person once bought all the feeder fish they had in a pet shop and kept them in the inflatable pool in the back yard to save them from getting eaten