can hard water eventually cause diseases in goldfish?

Question

the goldfish we had started losing their scales and one even turned white, even though it was the same color as the other two.

Answer 1

No, hard water will not cause disease and isn't responsible for the fishes current state. There are a few bacterial skin infections that can cause the problems you are seeing. The color change could be totally normal and genetic, but could also be linked to a disease. I would suggest treating the tank with Tetracycline or with Maracyn 2 for 10 days and watch your water quality very carefully.

MM

Answer 2

No hard water will not harm your goldfish. Goldfish will loose scales when it comes time for breeding. They will also change colors when coming into maturity. Do you know if your fish are males and or females?

they can also loose scales due to a parasite, however changing color and loosing scales, do you notice any chasing going on? How about any worm like parasites beneath the scales?

Don't worry the scales will grow back. I would keep my eye on the fish If you notice any parasites beneath the scales, then I would treat. You can supplement their diet with things like Lettuce, mustard greens, turnip greens, collard greens, spinach, peas, endive, seaweed, cukes, kale, chard, broccoli, lima beans, green beans, etc. and feed aquatic plants (e.g. duckweed, azolla, salvenia, etc) or hair algae daily.

For their Carotenoids which are a family of pigments the fish can't make themselves and are obtained as part of the diet. These pigments result in red, yellow and orange colors. Fish have cells called chromataphores. Those cells convert lutein and carotenes into astaxanthin which is the red pigment.
sources include, brine shrimp, krill, spirulina, marigold flowers, paprika, sweet red peppers, yams, carrots, pumpkin

Watermellons and oranges are also good as well as proteins like chicken (chicken livers) beef (livers and parts) and pork as well as worms and bugs.

Answer 3

Are they losing a lot of scaes or just a couple? How long have you had them? My Goldfish freaked me out like this once when they molted into bigger fish. My pretty Orange one lost a bonch of scales behind his gills and started turning brown. I almost put him out of his misery when i found on the net that this is normal. However you need to figure out if it because of the age or if it is a bacteria. There is a bacteria that makes them lose scales.

Answer 4

I had goldfish in very hard water and they liked it. you have to find another cause.