Sick Peppered Cory- Help Please

Hi all, I’m hoping for some help with my sick Cory.

Yesterday I was doing a water change and partial gravel clean and noticed that one of my Cory’s was stuck to the filter intake by his tail. He looked fine, so I dislodged him, but he fell to the bottom of the tank on his side and didn’t move. He honestly looked dead, but he wasn’t floating. I removed him from the tank into a bucket thinking he was either dead or about to die and he just laid there on his side. After a few minutes though I saw slight movement, so I turned him right side up and gave him a bit of a jiggle and he swam a little bit to get away from me. Then stayed still, but with his gills moving and his whiskers twitching.

I set up my quarantine tank and moved him in and checked on him through the evening. He seemed to get a little more lively, but not a lot. This morning he is the same- alive, but not moving unless I prod him. He seems a little worse than last night. 

I’m quite worried- he doesn’t seem to have any physical symptoms, he looks totally fine, but clearly isn’t. The other Cory’s (and other fish) in my tank are behaving normally- very lively and active. Does anybody have any tips or ideas?

It’s a public holiday here so nothing is open locally, but I could drive to one of the big fish stores about 1.5 hours away if anybody thinks there is medication or treatment or something that could help. I dosed the quarantine tank with API Stress Coat+ when setting up.

I have a 50 litre lightly planted community tank with a dwarf gourami, 8 Harlequin Rasboras and 3 Peppered Corys. Ammonia, nitrates and nitrites are all at 0. My tank has been cycled with all happy fish for 6 months after upgrading from a smaller tank with just the gourami which had been running for 6 months before that. The most recent change was a single new Rasbora that I added 2 months ago. I’ve also had a little bit of algae recently which I’ve been controlling with water changes- i suspect it is because I have a very bright house and it is mid summer (I’m in Australia).

The only notable other thing was that when I tested last night my PH was high- about 8. This was strange as my pH is usually really consistent. I used a combo of pH down and some rainwater (which has a low pH) for the water change and got it back to 7 before filling my emergency tank.

Happy New Year. 

I agree with everything that Hampalong has suggested.
The cory *may* be weak or unwell, and hence why he was sucked in against the filter intake. However, there's no clear indication of what is wrong, and medicating him for something that isn't clearcut would be of little benefit and is more likely to weaken him further and potentially irreversibly (ie be fatal).
I've had fish that have experienced stress (eg getting trapped in an ornament, or having been pursued in-hindsight-for-too-long around the tank to catch and isolate in a quarantine tank) and it does take a few days for them to recover from this.
Consequently, I would also agree with the "wait and see" approach.

H's suggestions of moving the filter position up so that intake is above substrate level, and avoiding the various products, are wise.

Is he eating? One food I've found helpful for a weak/ailing fish is Hikari First Bites - if put in below surface level, it disperses into the water and fish inevitably ingest it - helps strengthen them if they're unable to make the effort to retrieve or have little desire for other food.

Best of luck and keep us posted.

Welcome to the forum, btw.

When fish sleep it’s not a deep sleep. They can still react to danger if they have to. They can also drift around a bit. It’s likely it could have drifted into the intake while ‘half-asleep’ as it were.