Sick SAL

[toastyoasty]

Hello-

I am having a problem with my poor South American Lungfish. He is currently about 18 inches long, being grown out in a 55 gallon until a bigger tank is set up for him. For the past several weeks, the area around where his gills would be, if he had gills, has been getting rather swollen. I've been keeping an eye on him but he hasn't seemed to be having any problems.
I cleaned out my tank today and he was still swimming about without problems. I went out for the evening with my family, and when I came home several hours later, he was belly up at the surface, just floating around. I started messing with him a bit and it took a while before he came to and started swimming around at the surface again. He tries to swim down, but then just ends up bobbing back up to the surface, belly up.
I don't know what the proper way to treat him would be. I have aquarium salt, should I dose the tank with some of this? Or is there a kind of food I should try to get him to eat to get his correct buoyancy back?
Please help! He is my favorite fish and I don't want to lose him :[

 

[Wiggles92]

I'm not sure what is wrong with your SAL, but you may have better luck finding a solution if you post this is the "Freshwater Diseases and Health Issues" forum.

Adding some aquarium salt (1 tbsp per 10 gallons) to the aquarium may help. Be sure to mix it in with some water from the aquarium in a separate container before adding it.