So...my two striped cories have been acting very lazy for a bit now, but especially over the past few days. Everyone else in the tank(including 3 other cories) are completely fine. Last night I noticed one of them had 'fainted' which was alarming.
I tested the water yesterday and and everything was fine - nitrites were the only thing over - 20 ppm(which was different, it's usually around 5), but nothing crazy. pH is always high due to the tap water, around 7.0 but that's how it's always been. I did a 30% water change this morning. I added prime and Flourish excel for the plants as I always do. I usually change water every Sunday but I've been crazy with work so a bit behind - a few days shouldn't hurt though.
The tank is right next to my desk and all of a sudden I notice one of them is, what looks like, having a seizure. Swimming in crazy circles, up to the top, hitting the surface, falling to the bottom. I grabbed my camera and recorded it so hopefully this will help diagnose/determine what I should do. You can see the other sick one around the 20 second mark just sitting at the bottom. The others are swimming like their hyper selves.
He then floated up to the top, lay there on his side for a few minutes, and then back down into the plants. He's still breathing very shallowy, head up tail down, between the leaves of a water sprite but otherwise not moving.
I don't have a second tank to isolated him in and I'm sure he's dying - and the second of the same type is still acting very lethargic on the bottom of the tank. Could something have happened to just those two? It's so strange, no one else seems different at all. So confused why it's just to this species. I have three other cories - two albinos and one unknown(weird grey color w/an orangeish top fin, very happy perky guy). Rest of tank are tetras and a couple shrimp.
I'm afraid it looks like a nerve problem - something with the chemicals I use on the water/plants?
Do I leave him to die, put him out of his misery, I'm so confused as to what just happened.
I uploaded the video, hopefully this will help diagnose the problem. I'd hate for this to happen to any others.
Cory catfish seizure - YouTube