So I've got three black kuhli loaches, and one of them is ill. He is "stuck" to the surface of the water, just kind of dangling there until another fish bumps him, and then he'll try really hard to swim down, but just floats back up. I know these fish can swallow air and absorb oxygen through their intestines, and I saw this one doing it quite frequently, and now he seems to be full of air with no way to release it. The other two are just fine, and I don't think there is a water issue as there are plenty of fish swimming happily near the bottom of the tank. Any ideas or tricks to help the little guy? He seems quite uncomfortable and exhausted from trying to swim downwards and then inevitably floating back up.