HELP...ich on new bought aro

[NTH]

Hey guys.

I just bought a juvenile arowana about 4 inches.

On the 3rd day I fed it some crickets and it ate two. Later the afternoon I saw some ich developing on his head and 1 on the scales. The cotton like ich on the scale has a red tinge to it.

It is housed in a 822 tank. temp 25. I immediately added 1% salt which is about 420 grams of salt. I have raised the temp to 30 degrees.

It is still going up, currently 26-27degrees. Arowana is swimming around but opening mouth.

Will the drastic rise in temperate shock it even more?

Please help.
Thanks in advance