Should you be worried if your Betta fish looks like its scales and fins have been attacked even when it is alone?

Yes!!! Any time your betta does not look and act healthy and happy, you should be concerned. Do an immediate 100% water change. Treat for ich and fungal infestation. Repeat the 100% water change every third day along with the treatments. If the fish does not show signs of improvement, begin treating for bacterial infection. Hopefully the fish will recover and regrow its scale and fins.

Always keep your betta in clean water. A healthy betta requires a weekly 100% water change. Do not over feed.

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I don't know but that answer didnt sound entirely right to me.

Never give your fish a 100% water change

but don't think im saying don't change the water, you should change about 20% of the water out. If your fish ain't looking to good then i suggest you do it every day. this gives your fish time to relax after each change.

Never start dumping random fungal/infectection treatments in your tank when you don't know whats wrong in the first place

this stresses out the fish and can make problems a whole lot worse.

It depends what you mean by attacked.

If it has white dots/fluffy lookin stuff then you should treat for ich

If there is a yellowish dusty kinda thing then it is probably a disiese called Velvet which can be easily cured unless it has already progressed a great lengh?

You could also try using Aquarium salt in your tank if you don't already. The fish will live longer because the salt has a kind of natural/theriputic effect on the fish