Minnow with swollen gills, need help, and fast!

[Whitecloudminnowguy09]

Found out last night that one of my minnows was swimming almost sideways, with rapid breathing, and red gills, and swollen gills. I did an emergency 5 minute 1 tbs to 1 gallon aquarium salt bath, with an airstone inside. I have Kanaplex and API fin and body cure on hand. He made it through the morning. He is back in the tank, at the bottom of the tank, by a airstone. Still breathing, slower though. I need to know the next step.



Parameters are fine. 0 ammonia. 0 nitrite. 20 nitrate. (Going to check them again this morning)



Please help with advice, anyone! If he does die, would love to know what happened and why he got this. All of the other fish are fine. Thanks!

 

[Whitecloudminnowguy09]

Can anyone help me?! My ammonia is actually .25 ppm. I had a spike 2 years back, but the tank is super established and very cycled. Idk what my next step should be. It is 75% on its side right now. But still breathing. help!

 

[Rusty_Shackleford]

I would do an immediate large scale water change.

 

[Whitecloudminnowguy09]

I would do an immediate large scale water change.

Just did. And added kanaplex. The minnow looks a little better now. Thank you @Rusty_Shackleford