Originally Posted by Falina
Minimum recommended tank size for 1 goldfish is 30 gallons, + another 10 gallons for an extra fish.
Hope this helps.
I just wanted to make note that the 30 gallon is for starting
with a goldfish. A fan tailed goldfish grows to about 8 inches full grown, and by that time will need a minimum of 90 gallons. I have seen healthy fish grow from 1 inch to 6 inches inside of 2 yrs.
The other problem here that I didn't see mentioned is the oxygen content in the water. Aside from the waste affecting them (which will continue until the tank is fully cycled) so will the oxygen content. Goldfish consume more oxygen than the average fish, so adding an air stone will help a lot.
I agree with the others except with the 10 - 15 water changes in a day. If that should have been 10 = 15% of the tank water every day that would have been accurate. With that many and that kind of fish in that size of a tank... daily water changes will be needed to keep it going short term.
Another easy way to control the pH in your tank naturally, safer... add some peat moss to your filter. This will require a good liquid pH test kit. If you're using strip tests, please be aware that these are known to be extremely inaccurate and unreliable. You'll need to use liquid kits to get accurate results.
Another issue I see is flake food with fan tail goldfish. This is just inviting more problems. Fancy goldfish should eat sinking pellet food
and other sinking foods only. If they feed at the surface they gulp a lot of air, which in turn causes severe swim bladder issues that can be fatal.
As the others have said, messing with your pH with chemicals can quickly become deadly. Goldfish should be able to thrive in pH of 8.0 without any problems. If they were originally in softer water, then the shock of the change can cause problems, but they should be able to adjust to it easy enough. The average pH around here is 7.8 - 8.0 and I've been keeping goldfish for years. I currently have a 5 inch oranda that I rescued about 3 yrs ago. His pH is steady at 8.0 and he is thriving. The chemicals are a sure way to kill all of your fish really fast.