It's either an external protozoan infection or excess mucous.
Fish have a thin layer of clear mucous/ slime over their body. When they are stressed by something (chemicals in the water or disease organisms), they produce more mucous and it can appear as a cream or white film over their body or fins.
The best treatment for excess mucous is doing a 75% water change and gravel cleaning the substrate every day for 2 weeks.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.
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Fish rubbing on objects in the tank are usually infected with external protozoan parasites that bite the fish and irritate it. The fish tries to brush the parasites off by rubbing on objects in the tank.
Poor water quality or chemicals in the water can also cause fish to rub on objects.
External protozoan infections can be treated with salt, Malachite Green, Copper and a few other chemicals. Salt is safest. Malachite Green causes cancer.
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Furan 2 is an anti-biotic and will not make any difference to external protozoan infections.
Anti-biotics should only be used on known bacterial infections that have not responded to normal fish medications. Improper use or mis-use of anti-biotics can cause drug resistant bacteria that can kill people, birds, animals and fish.
Anti-biotics like Furan 2, can also wipe out your beneficial filter bacteria and cause the tank to cycle again.
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How long have you had the fish?
Have you introduced anything new to the tank in the 2 weeks before this started?
What sort of filter do you have?
How do you clean the filter?
How do you clean the sand?
What is the ammonia, nitrite, nitrate and pH of the tank water (in numbers please)?
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Test the tank water and then wipe the inside of the glass down with a clean fish sponge. Do a 75% water change and gravel clean the substrate every day for 2 weeks and post some clear pictures during that time. If the cream/ white areas get worse we can look into adding salt or chemicals but do some big water changes first and tell us how you clean the filter.
Hold your phone horizontally when filming or taking pictures so the image fills up the entire screen and not just a small section in the middle.
