Sunburst Anthias not swimming right

[Reflective]

So I've had a Sunburst Anthias in QT for 23 days now. It was eating and swimming great up until this afternoon. When I went to feed it, it wouldn't come out from under the rock. Then after watching for a while it tried to swim out, but went sideways then decided to go back under the rock. It tried to come out a couple times but would either flip sideways or upside down then it would go back to the rock.

Anything I can do for it?

 

[Piranhapat]

How much was he eating? Is he alone in QT or any other fish in there? Do you see if he was breathing heavy. Keep the lights off and see if he comes out. Try feeding him only when lights are off. They shy fish and they not bold. How big is he?

 

[Reflective]

I'm not sure of the exact amounts but comparing the eye dropper I use to a syringe from one of my test kits, he probably gets .5-1 ml over 4 feedings a day. I slowly feed over a minute or two so there isn't a lot of food floating around my QT tank.

There was a Black Cap Basslet in the QT with him. I actually took him out of QT and he is in a bucket right now with a chunk of cheato from my display tank and an airstone. Didn't have a filter pad that's been in the display tank long enough so thought the cheato might have some beneficial bacteria on it. He's currently under the airstone. I moved it once when I couldn't see him and he pretty quickly swam to get under it, but was definitely swimming sideways/upside down.

Wasn't/Isn't breathing heavy. He is about 2" I think. He hasn't been shy for quite a while. Always eager to eat when he would see me come in the room.

 

[Reflective]

I take that back, he probably gets .5ml per feeding. But again, I'm guessing. I just feed from the eye dropper for a minute or two and squeeze more out when they come back for it.

 

[Humblefish]

Is he currently being treated with any meds (or hypo), or has been exposed to any meds during the QT period? Have you double checked ammonia in the QT?

 

[Reflective]

No meds or ammonia.

 

[dbrewsky]

decompression issues affecting swim-bladder?

 

[Reflective]

How long does it normally take for those symptoms to show up?

 

[Reflective]

I have heard about an aquatic vet here in san Diego. If he is still alive tomorrow I might try that

 

[dbrewsky]

My understanding is most decompression related injuries tend to cause fatalities often before they reach the retailer, But I just thought I would throw it out there since they are a deeper water species

 

[Piranhapat]

I don't think it's that. You have him over 23 days. Hard to tell without see him. But either black cap scared him. Maybe becoming more aware and doesn't like lighting. Is the Qt tank cycled. Is the Nitrate good. What's salinity and has that changed.

 

[Reflective]

Didn't make it through the night. Double checked nitrites (0) and nitrates (<5 with API test kit, 0 with Salifert). SG is 1.025. I was doing water changes of about 20% every other day to get any poop out... Too much maybe? Never cycled the tank but I used a filter pad and HOB filter that had been in my display tank for month. I also did ammonia, nitrites and nitrates every time I did a water change... Maybe a mini cycle happened in between testing? I have an ammonia badge in the tank and it never changed from yellow.
Sad because yesterday morning he was doing fine/normal, then yesterday afternoon I didn't see him out when I got home and when I went to feed him so I knew something was wrong. The only times he ever hid was when I was doing a water change, then he'd come out within minutes of me finishing. Showed some aggression from him towards the black cap maybe two times when I was about to feed them, but otherwise the black cap hangs out in the rocks.
I still have the body. Quick glance and I don't see anything abnormal, but I don't really know what I'd be looking for. Is there something I could look for to give me more of an idea of what happened?
Thanks for the help

 

[Humblefish]

You could drop the body in FW to see if flukes emerge. Flukes turn white when exposed to FW, and will fall out of a fish (especially out of the gills) in less than 5 mins. If that doesn't yield any results, then I think you are just gonna have to chalk this up to an unexplained death. It sucks but happen sometimes. You never know what might have gone wrong with a fish internally. I don't think decompression issues or swim bladder disorder would have killed this quickly though.

I am sorry for your loss.