i have 90 gal.1convict, 1 puffer, 1jewel,1electricyellow, 2pleco,1balashark,9glofish, 5tigerbarb,1catfish. have had these all for over year. i noticed 1 day fish were not so active then they didnt eat(which is so unlike them) i checked water and took it to the petstore to be checked. it came up fine. but my fish were not acting normal. i had done a treatment for velvet the month before and they seemed better. i did a 30-40% water change..convict died and a tiger barb died. waited a week noticed alittle algae in tank and was told because tank was in front of my window that might be causing algae therefore my sick fish. so i decided i had better move it. i got water ready in other tanks to put fish while i moved tank started moving fish into other tanks. all started dying. i lost shark, barb and glofish. so i just put the ones that were still alive back in tank and filled it back up. last night i heard splashing and puffer was dive bombing the bottom of tank then head over tail spins to the top and back down. today he is fine. jewel is listless. i dont know what to do. i have moved them once before and cleaned entire tank before so i have transferred them twice with no problems. yes i have been adding salt to tank for year since i got puffer. never any problems with other fish until now.