It's not white spot or gill flukes.
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You should not add medications unless you know what the problem is. All medications harm the fish and mis-use of medications can cause drug resistance in various diseases.
Never use more than 1 medication at a time because you can poison the fish.
The first course of treatment for any sick fish is test the water and do a big (75%) water change and gravel clean the substrate. The water change dilutes nutrients and disease organisms in the tank and buys you some time to work out what is going on.
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The fish appears to have bits of fin and tail missing, as well as scales.
What other fish are in the tank?
How long have you had the Glowlight tetras for?
How long has the tank been set up for?
How often do you do water changes and how much do you change?
Do you gravel clean the substrate when you do a water change?
What sort of filter is on the tank?
How often and how do you clean the filter?
What is the ammonia, nitrite, nitrate and pH levels in the tank (in numbers please)?
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The following link has information about what to do if your fish get sick. It's long and boring but worth knowing. I recommend printing it out and reading it in bed to help fall asleep.
https://www.fishforums.net/threads/what-to-do-if-your-fish-gets-sick.450268/