a common salt treatment is 1-3 part per thousand, that is 1-3 grams per litre of water.
so for you 2 grams per litre would be a good start.
the ocean is around 35 ppt. most freshwater fish can tolerate up to 5ppt easy enough so definately dont be worried about 2ppt. so if you have a 200 litre tank then you can use 400 grams of salt. dont use table salt.
just keep an eye on it. salt can be used to reduce a nitrate spike too.
Guys Its been more than a week since i have been changing the water once every 3 days and plus i have been adding salt and anti fungal medicine also. i have increased the air supply also. but my arowana doesn seem to recover. its gill covers are still opening and don seem to stick back.
any suggestions beyond at this stage?
It is safe to add salt. 1 table spoon for 10 gallons (can go up to a table spoon for 5 gallons also - i use 1 for 5). Add salt to the water during water change. MAKE SURE you dissolve the salt first.
MAKE SURE it is rock salt and not iodized/fluorized salt
Lastly, do you use dechorinator? Should always let the water to stand for at least couple of hours before adding it to aquarium.
Picture of a gill curl would be addition to the database
