Tail and fin rot problem

[miinhuey]

I just set up my aquarium a week only. Last two days I found that my spiny eel has serious affected by rot tail and died already. This morning, I found that my blue gourami and mable angel seem to be having the same problem but it is at the begining stage. Both of them are passive compared to their normal self, floating at the top of the aquarium. My tank is 36 incies, I have put 3 capsul of antibody with 3.5 cups of anti parasite formula by Danios. Do you all think that I need to add in salt also? If yes, how much should I put? Help me. This is my first time having an aquarium. Oh ya, after I put all the above mentioned medicine, it seem to have a lot of bubble at the top of my aquarium. Also all a long my aquarium water are crsytal clear as i used tension gon and live water also.Thanks in advance