Cardinal tetra not eating, behaving/looking fine

Hi everyone, so I’ve had quite a bit of a problem with cardinal tetras lately. You can read my previous post about this here: Giving up on cardinal tetras, can I add neons? | Aquarium Stocking Forum | 520978

From my last batch of cardinals and massive die off, 1 has survived in the QT tank. After the last death in the tank, the remaining fish got ich. I successfully treated the fish with Rid Ich plus and it’s been 8 days since I last medicated the tank with it and it’s been almost 2 weeks without visible symptoms of ich.
The fish itself has always been a glutton but for a few days now it’s stopped eating. I’ve caught it a few times picking at the food on the bottom once I went away, but still no voracity that it used to have.
It also now has suddenly looked “bigger”. From my experience with other cardinals, it looks gravid but I’d like confirmation it’s not dangerous bloating.
Besides these 2 things, the fish behaves and looks fine, it’s very reactive and has colored up nicely. I feel like it’s mostly stressed by being alone now for almost 2 weeks (it ate the most fiercely when it had company). My gut says itll be fine to add it to the main tank (where it’ll have other cardinals) but I want confirmation that it’s finally healthy.

Mandatory maintenance info, with the rid ich I changed the water 30% daily, now I’m doing 50% twice weekly. QT tank is cycled and parameters are perfect.

Picture of cardinal in question below, colors look off since the QT is a plastic storage tote

 

How many of them do you have left? Could it be that you have to little of them left and they are stressed? When my ember tetras died and only 2 left, they refused to eat so I bought more and they started eating again.

 

How many of them do you have left? Could it be that you have to little of them left and they are stressed? When my ember tetras died and only 2 left, they refused to eat so I bought more and they started eating again.

Thanks for responding. In the QT he’s the only one left after the massive mysterious die off (I’ve had really bad luck with cardinals lately). In my main tank there’s others so I was wondering if maybe he’ll perk up after seeing friends. Thanks for sharing your experience, helps me feel better about it.

Do you think the fish looks okay physically? Can’t tell if bloated or gravid

 

I think is gravid as it’s the whole part that looks swollen and not just like the front part. Might be wrong though.

 

I know it’s been a while but in case anyone uses this thread as a resource, the fish was definitely gravid. Swelling completely disappeared once added to the main tank with the other cardinals (including some excited males). Fish is perfectly healthy.