I have a 110 with 2 bola shark grown, 2 clown loaches, 1 rainbow shark, 1 pleco. Well the tank has been up and running for about 5 years with the same fish in it. My nephew brought me 2 goldfish he won at the fair tuesday and ive had 1 before for i just put the bag in for 30mins and let the fish go in the tank. the gold fish died with in 36 hours. the day after the gold fish died i noticed the bola sharks wouldnt spook and one of them the eyes looked cloudy. later that day the same shark was upside down i picked it up and got him going again and it would swim for a few sec and just give up and flip upside down. it died within a hour. last night I did a 40% water change and this morning the other bola shark was dead and the rainbow was swimming upside down sideways slowly. it died within a few hours. now the i added seachem kanaplex now the one of the clown loaches is acting up not swimming right. what is wiping out this tank?