sory to hear it bro. i had a tig in my ray tank a while back and i too dosed the tank with nitro. the tig wasnt sick when i dosed the tank but within hours of hitting the tank with nitro he began to pant. the following morning i arose to see the tig beginning to show signs of red streaks that i then believed to be septicemia. theorizig that it was indeed septicemia i ran the full course of the nitro. withing 4 days he was DEAD!!!!
looking back and having read your post here is my NEW theory. i think that the TIGs are sensative to the fact that Nitro depletes the water of dissolved O2. TIG's need TONS of dissovled O2 to thrive. the longer i ran the meds the more the was starved for O2. the red streaks werent septicemia at all but the tig showing signs of O2 starvations stress. you know when humans go for a jog or go for a marathon sessions with their girlfriends how their faces turn red? well that red color you see is the blood vessels pumping extra blood to the skin to try to cool off since the body is in an elevated stress level and seeking extra O2.
i will never put nitro in a tank or anywhere near a tig ever again. hopefully my theory is wrong and u can save ur tig!!! i wasnt so lucky....
p.s i think IMHO that is too much salt. salt in high doses makes fish SH*T and you dont want him to loose more food than he has to. if he isnt eating, as i am pretty sure that he's not, then he has less reserves to heal himself. BTW... catfish farmers dip their cats in a salt bath so that they SH*T out as much food as possible before they cut them up for people food!