Why do fish sink to the bottom of the tank?

It could be doing lots of things like:when its sleeping,or it just might be sick.You need to wait just in case it wakes up.If it doesn't wake up after 12 hours(It matters on how long it has been there), you need to take it to the vet to get it treated or to see whats wrong.I hope my answer helped you.Good Luck!

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