Have a question I have a 55 gallon tank fresh water ..stones for substrate and live plants ..i do check water for ph and nitrates and ammonia weekly...lately I had 8 long fin tiger barbs which 2 now died without any signs..but my biggest concern I have one tiger barb who has his mouth frozen open and doesn't close and was very red near mouth . Recently I have been adding Api..E.M erythromycin and redness is slowly going away but his mouth is still open and worried if he can eat ...does anyone know what this issue might be plzzz?