Fish either has lockjaw(which I doubt, gill flukes (which is possible) or may have swallowed an object it cant pass and has mouth opened to get maximum breathing.
I do not see a video.
looks like something is lodged. Is the fish eating ?
Pellets, yes! I bought some very small pellet food with the fish. They didn’t seem to love them and they’d try to eat them but spit them out (very hard little things that didn’t seem to soften up very easily). I’ve now been feeding them freeze dried mysis shrimp for the last few days. Both fish seem to get more excited for that food. Now that you mention it I didn’t notice the mouth issue until after I fed them pellets.
It’s definitely having difficulty. It will go to surface when food is floating but won’t visibly bite at the food. I believe I’ve seen it catch food in its gaping mouth when it’s floating in the water column but can’t be sure it’s been able to swallow. Wonder if I chase him around the tank a bit to get him moving quickly if that could dislodge whatever is the issue.
I chased him around a little bit using a net but wasn’t able to catch him to take a closer look. Turns out I should have been more careful about how many rock crevices there were when aquascaping lol. I also tried feeding some brine shrimp to see if it might coax him into eating. Basically there has been no change (maybe the pale white colour has gotten worse?). I’ve taken a little more video to look at but wondering if there is any other treatable ailments I should try treating? These are the only fish in the tank and I don’t have a QT yet. If there was anything I could add to the DT as a shotgun approach I’m wondering if it would be worth a try.
Sorry, I don’t have any other ideas, maybe somebody else will chime in.
