Time to euthanize or is this treatable?

[rebe]

Noticed this on one of my panda corydoras less than a minute ago. I got these fish 11 days ago, and they're being quarantined with some rasboras I got on the same day. This must have grown within the last 2-3 days.

The clip below is from 3 days ago when I took all of the corydoras out to inspect them, no sign of this at the time.

 

[Colin_T]

The white fluffy stuff sticking out the side of the catfish is Saprolegnia fungus and can be easily treated with salt. The fish gets injured and the fungus gets into the wound. No need to euthanise.

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SALT
You can add rock salt (often sold as aquarium salt), swimming pool salt, or any non iodised salt (sodium chloride) to the aquarium at the dose rate of 1 heaped tablespoon per 20 litres (5 gallons) 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.

Keep the salt level like this for 1 week.

The salt will not affect the beneficial filter bacteria, fish, plants, shrimp or snails.

After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.

If you do water changes while using salt, you need to treat the new water with salt before adding it to the tank. This will keep the salt level stable in the tank and minimise stress on the fish.

When you first add salt, add the salt to a small bucket of tank water and dissolve the salt. Then slowly pour the salt water into the tank near the filter outlet. Add the salt over a couple of minutes.

 

[rebe]

@Colin_T Thank you for the advice and instructions. I did add the salt you suggested today, and he seemed fine. I sadly just found him dead in the tank

Should I wait a week before starting to reduce the salt with water changes? Or is it pointless to keep the salt levels up if there aren't any fish with signs of fungal infections?

This seems to be a poor quality group of fish. I bought 14 of these corydoras pandas and 11 days later I've lost 3 of them.
The first was the smallest of the group, and he was missing part of his tail (from when I got them, not an injury suffered in my QT.)

The second fish seemed to have died during the night, and had no signs of illnesses or infections of any kind.

The third fish was this one, with the fungus.
This group will be getting a longer period of quarantining than I usually do.

 

[Colin_T]

Keep the salt in there for a week before diluting it out. If there are any minor infections the salt should stop them developing.

The fish that died today also had no barbels. Check the others to make sure they don't have red barbels (bacterial infection) and hopefully they should be ok.

 

[rebe]

The fish that died today also had no barbels.

Yes, I noticed after I brought them home that many of them had no barbels. I wasn't quite sure if they were just growing because they seemed young. I thought they must have been kept on an unsuitable substrate before I got them, unless there are other causes of bacterial infections that erode the barbels.

My tank has a soft play sand substrate so I don't think that would cause bacterial infections.
I've kept the water clean, no signs of ammonia, nitrites or any nitrates above tap water level (7ppm).

 

[Colin_T]

Fish that size should have full length barbels so they were probably kept on a bad substrate that damaged them. It might be why you are having trouble with them now, they were housed badly before you got them.