I have a problem... 30 gallon tank... Found dead angel fish today. Tested water and ph 6.0, usually 7, so put 2 tsp baking soda and salt added water with dechlorinator... Now fish swimming crazy...
Tank has large koi angel(favorite) swimming funny
Fancy goldfish
5 neon tetras
Blue dwarf gourami
5 angels( smaller)

Any help much appreciated!!!!