fin rot question

[QUESTPACT]

so i have a double divider tank with 2 siamese fighting fish in it and the one guy has fin rot so here's my questions

1. how should i treat him
2. should i quaritine him / will the other fish be effected by it cause its the same tank just with a divider

 

[guppy]

First bump up the O2 levels and filtration as clean, well areated water is the best thing to clear up fin rot, second, treat the tank with either Jungle's fungus eliminator and tetracycline or with a combo of Maracyn and Maracyn 2. It will also help to do 30-50% water changes daily until cleared up and to raise the temp above 83F.