Pictures of the fish so we can confirm it is white spot?
Salt does not treat white spot.
When using heat to treat fish for white spot, you need to get the water temperature up to 30C (86F) and keep it there for 2 weeks, or at least 1 week after all the white dots have gone.
Use a thermometer in the water to measure the temperature.
If the goldfish were in cold water (less than 20C/ 68F), do not use heat because they don't tolerate a massive temperature rise over a short period of time.
If the goldfish are in water with a temperature between 20-24C (68-75F), then raise the temperature over a couple of days.
If the goldfish were in a warmish tank (24C+/ 75F) then you can use heat (30C) and raise the temperature over a 12-24 hour period.
Whenever you use heat or medications in the tank, increase aeration/ surface turbulence to maximise the oxygen level in the water.
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Before raising the temperature or using chemical based medications to treat a disease, do the following things:
1) Wipe the inside of the glass down with a clean fish sponge. This removes the biofilm on the glass and the biofilm will contain lots of harmful bacteria, fungus, protozoans and various other microscopic life forms.
2) Do a 75-90% water change and gravel clean the substrate. The water change and gravel cleaning will reduce the number of disease organisms in the water and provide a cleaner environment for the fish to recover in. It also removes a lot of the gunk and this means any medication can work on treating the fish instead of being wasted killing the pathogens in the gunk.
Make sure any new water is free of chlorine/ chloramine before it is added to the tank.
3) Clean the filter if it hasn't been done in the last 2 weeks. However, if the filter is less than 6 weeks old, do not clean it. Wash the filter materials/ media in a bucket of tank water and re-use them. Tip the bucket of dirty water on the garden/ lawn. Cleaning the filter means less gunk and cleaner water with fewer pathogens.
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If you use chemicals to treat fish, do the following things:
Work out the volume of water in the tank:
measure length x width x height in cm.
divide by 1000.
= volume in litres.
When you measure the height, measure from the top of the substrate to the top of the water level.
If you have big rocks or driftwood in the tank, remove these before measuring the height of the water level so you get a more accurate water volume.
You can use a permanent marker to draw a line on the tank at the water level and put down how many litres are in the tank at that level.
There is a calculator/ converter in the "FishForum.net Calculator" under "Useful Links" at the bottom of this page that will let you convert litres to gallons if you need it.
Remove carbon from the filter before treating with chemicals or it will adsorb the medication and stop it working. You do not need to remove the carbon if you use salt.
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The white spots fall off the fish after a few days and the parasites sit on the bottom of the tank multiplying. Just because most of the spots have gone, it does not mean the problem is nearly over.
The following link has information about white spot and how to treat it. Post #1 and 16 are worth a read.
This is a common question that is often asked, what is ich and how is it recognisable and what causes it? The real term is ICHTHYOPHTHIRIASIS. OR commonly known as white spot. It is an extremely comon parasite that affects aquarium fish. It is highly infectious and potentially lethal and...
www.fishforums.net
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After you have finished treating the fish, you can turn the temperature down and do water changes and gravel cleans like normal. You can also clean the filter like normal.
eg: Wash the filter materials/ media in a bucket of tank water and re-use the media. Tip the bucket of dirty water on the garden/ lawn.