How long to use salt with maimed goldfish?

[Jim Sinclair]

It's been just over a month since I realized my adult goldfish were chewing up the baby goldfish that I'd thought were safe with them because they were too big to be swallowed all at once. The injured little fish have been in a convalescent tank with salt added at 1 tablespoon per 5 gallons of water, with daily partial water changes and the salt replenished with the new water. They're all still alive, all swimming, and all eating. One has changed color. The fish that had the damaged bulging eye, and the fish that spent about 3 days lying on the floor of the tank, have both recovered to the point that I can no longer tell which fish they were. Some of the tail fins seem to have healed/regrown to some extent. Others have not. I wonder if it's a function of how much of the fins were left in the first place, and maybe the ones that were completely amputated have nothing left to grow back? The one that lost both eyes is still blind, obviously, but does not seem to have any difficulty swimming or finding food.

Here they were at feeding time last night (the particles in the water are sinking food):

My question is whether I should still be adding salt when doing water changes, or if it's time to stop adding salt? How long is it good for goldfish to be salted after being injured?

 

[Colin_T]

As a general rule you add salt for 2-4 weeks. If the salt has not fixed the problem after 2 weeks it isn't going to and there is no point continuing treatment with it.

Salt is used to help reduce the number of disease organisms in the water and give the wounds time to heal. It usually takes about 1 week for most wounds to heal over properly so no bacteria or fungus can get into them. The 2 weeks of salt normally gives the fish enough time to heal the wounds and for new tissue to start growing back.

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Dose rates for salt are below.

You can add rock salt (often sold as aquarium salt), sea salt or swimming pool salt to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres of water. If there is no improvement after 48 hours you can double that dose rate so there is 2 heaped tablespoons of salt per 20 litres.

If you only have livebearers (guppies, platies, swordtails, mollies), goldfish or rainbowfish in the tank you can double that dose rate, so you would add 2 heaped tablespoons per 20 litres and if there is no improvement after 48 hours, then increase it so there is a total of 4 heaped tablespoons of salt per 20 litres.

Keep the salt level like this for at least 2 weeks but no longer than 4 weeks otherwise kidney damage can occur. Kidney damage is more likely to occur in fish from soft water (tetras, Corydoras, angelfish, gouramis, loaches) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers, rainbowfish or other salt tolerant species.

The salt will not affect the beneficial filter bacteria but the higher dose rate will affect some plants. The lower dose rate will not affect plants.

After you use salt and the fish have recovered, you do a 10% water change each day for a week. Then do a 20% water change each day for a week. Then you can do bigger water changes after that.