Changy can he swim around and switch between top and bottom? Because i lost 2 guppies for swim bladder disease and i got a 3rd one sick, pretty bad isn't? When I realised the 3rd one was sick and my water parameters was fine i went to my fish shop to have a chat, and they got plant of treatments for swim bladder disease which I couldn't use the strongest ones because it would kill my shrimps. So they suggested me to use a physiological salt called Aqualibrium from Interpet.
I started using this on the aquarium and the fish reacted on the 2nd day, he previously was hiding and when the light was on he was scared and staying between the shadows and after the salt he was swimming around. But u can not use this salt on a high concentration for more then two weeks because some plants can start feeling it and die, although I didn't have any problem with that.
On the 3rd week he start hiding again, I increased he salt on the water and doing some researches online I found that some people give mash peas to the fish with swim bladder disease, because ur fish can be sick for many many reason and it each fish reacts in a different way. I had one that couldn't sink in the water and the others two were staying on the bottom. So the peas help the fish if the problem were over feeding.
Weird it may sound it worked for me, the salt combined with the peas. For the peas I take just one on a glass with water and hit on microwave for 1 min or 1 min and 1/2, u take the skin off and smash it. It need to be really really tiny to fit on their mouth, they love it they go crazy to eat it.
Not sure if is the ideal solution not being sure if ur fish got swim bladder disease, the the salt perhaps is a good idea.
Interpet Aqualibrium Salt: Amazon.co.uk: Pet Supplies
I have the blue one.
Hope it is helpful, good luck.