answer:Goldfish need about a 7.2 – 7.6 range. If the PH is lower, it could be due to excess waste in the water. This raises the Ammonia level, which is not a good thing. If the fish is suffering due to the PH level, it might be slimy, lethargic, not eating, have some blood smearing it’s fins, then it might die. Regularly changing the water should improve the PH level, and the ammonia level. It can also help to add a small pump, that would introduce air into the water. Goldfish don’t care if the water is hard, or soft. Hardness is the amount of dissolved minerals in the water, and it varies in different areas.