Yes that is a sailfin this is a 33g i know its a little small of a tank for him but he has adjusted just fine to the tank, I have had him for about 7 months now but I may lose him tonight, as I have been bringing down my salinity in the tank with fresh water changes, I did one last one today to bring the salinity back to normal and now I have stressed him out big time, he is laying on his side breathing really hard, LFS said it was because I brought the salinity down a little too fast and he is stressing out because of it. This was my girlfriends fish so she is freaking out big time and I am worried for him as well,, guys at the LFS said they have had tangs do this as well and that they are over reacting to the change in the water. I will keep all posted.