For about the past two days my one year old black skirt tetra has been swimming franticly upward right next to my bubbler to no avail. He can only make it about six inches from the bottom of the tank, and he's been sitting basically in the stream of the bubbler non-stop. He looks normal, no bloating at all. His gills are a bit reddish, but they have been for almost four months. I determined with my local fish shop owner that he had some kind of fin infection and we treated him with antibiotics. Most of his symptoms at the time (gasping for breath, Red Fin
and gill base) went away, but his gills still maintain a reddish color today. I've been fasting the tank for about two days now, but he's not making any progress. I don't have him in my qt as it doesn't seem infectious and it seems to stress him out more.
His inability to rise to the surface and his erratic swimming seem to suggest swim bladder issues, and I know that black skirt tetras are prone to constipation, but wouldn't he seem bloated if this was the issue?
My water is clear and I change it regularly, I have a functional filter. My tank also has three zebra danios, a Chinese Algae Eater
, and another black skirt tetra.