Hi and welcome to the forum
Any chance of some pictures and short 60 second video of the fish?
If the pictures are too big for the website, set the camera's resolution to its lowest setting and take some more. The lower resolution will make the images smaller and they should fit on this website. Check the pictures on your pc and find a couple that are clear and show the problem, and post them here. Make sure you turn the camera's resolution back up after you have taken the pics otherwise all your pictures will be small.
If the video is too big for this website, post it on YouTube and copy & paste the link here. We can view it at YouTube. If you are using a mobile phone to take the video, have the phone horizontal so the video takes up the entire screen. If you have the phone vertical, you get video in the middle and black on either side.
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What is the ammonia, nitrite, nitrate and pH of the tank water?
How long has the tank been set up for?
How long have you had the fish for?
How often do you do water changes and how much do you change?
Do you gravel clean the tank when you do a water change?
Do you dechlorinate the new water before adding it to the tank?
What sort of filter do you have?
How often and how do you clean the filter?
Have you added anything new to the tank in the 2 weeks before this started?
Do you add plant fertilisers, supplements or anything else to the tank?
Are there any other fishes in the tank?
