Ich and fin rot ? How to treat, if that's even what it is?

[Morgand]

I have a 6 year old shibumkin that I have had in a 15 gallon tank since December. Prior he was in a smaller tank.
Everything was fine up until I introduced six tiny tetras into the aquarium. Within a week he developed what looks like ich, subsequently leading to what looks like fin rot.
I have treated him with API super ick cure . And done multiple water changes. The ammonia levels in my tank are non existent and my water is pristine. Although he seems to be getting worse. I have since purchased melafix and have given him one dose. Slightly concerned about medicating with both at the same time and their efficiency
Any advice would be appreciated ?
I have also heated the water to about 27°C. I am aware I could add salt but that's another scary idea ?
And I have also removed my carbon filters while the medication is doing its thing .
Please help !? I have attached two photos of his current state .

 

[libertybelle]

Welcome to the forum;.

The obvious thing to point out is that is a big (and potentially much much larger) fish in a tiny tank. Even if it’s not huge yet those guys get between a foot and a foot and a half. At six years old he’s probably already pretty large.

The red streaks are a classic sign of ammonia burn (sometimes they take a couple days to show up; maybe you had an unnoticed spike?) so I’d recheck all water parameters ASAP and post the actual numbers here. (Ammonia nitrite and nitrate at a minimum)

Adding tetras was an odd choice as they’re warm water fish; shubunkins like cooler water and the tank was already too small for that fish long term to begin with.

The water is being kept too warm for the goldfish which is likely stressing it out and as an added bonus red streaking can also be a symptom of bacterial infection. If that’s the case the warm water is making it even worse; bacteria love warm water and stressed fish!

 

[Morgand]

Adding tetras was by suggestion of fish store worker but I have since removed them to a warmer environment while my shubunkin tank sits at 22°C.
With the expectation of today to help rid the ich (I thought).
My ammonia nitrite etc levels are not the issue . My water changes have cleared up any potential for that .and I'm testing regularly.

Side note , since adding melafix only 8 hours ago he has perked up a wee bit .
I will get a larger tank in the mean time.

 

[libertybelle]

No offense intended but often people say their parameters are fine and it still turns out to be part of the issue once we get into it.

If they really are fine then we’ve ruled out that and can move on but It would really help to have some basic details such as the actual test result numbers and your water change schedule etc. It’s just the process of elimination questions we have to go through when diagnosing fish issues and deciding next steps.

unfortunately pet store workers give notoriously bad advice! Getting the fish back to it’s preferred temperature and into a bigger tank will likely help. As I said, bacteria love warm water so cooling things down can help with infections a lot if that’s what the problem is and lowering the fishes stress levels will help it’s own immune system help you.

How long has the fish been back at the cooler temp? I assume you raised the temperature when you got the tetras which was that same time the trouble started?

 

[Morgand]

I only had the temperature raised for about half the day today. I have since taken the heater out and I imagine with in a few hours it will be ideally cold again. I live in a very cold climate .
I did not bring the temperature up for the tetras.
I have attached a picture of my most recent ammonia test.

 

[Morgand]

The trouble started about 3 days after introduction of the new fish.

 

[Autumnsky]

How are things going?