Swollen Mouth Praecox Rainbowfish Only Staying At The Top

[Sunny Doan]

Any help? My female praecox rainbow developed some weird swelling on her lower jaw and is only staying at the surface of the water. I just did a water change yesterday but im not sure what could be affecting her. The male praecox is doing fine and the guppy fry in there are doing great too. Water temp is at 80 degrees, but I brought it down to 75. 

[FrozenFins]

I would try aquarium salt do reduce swelling. But to be sure of the cause can you send water paramerters as well as the picture of fish?

[Sunny Doan]

Sorry for the late reply, Ive been busy with things here’s a picture of her. She’s now staying at the bottom of the tank here’s a picture. I’ve added salt and will be testing water later today.