HELP WITH FISH... I THINK IT'S DYING?

I have 2 male guppies, mysrtery snail, dwarf gourami, play, diamond tetra, flame tetra, corycatfish, swordtail in my cistern.

just like 20 minutes ago i looked in my cistern and one of my guppies was like stuck in the plant, so i get him out and he swam to the bottom and like layed on the ground. he tries to swim up but he like turns sideways then give up and sinks down again, then he will get caught in the filter... whats wrong next to him! Hes always a very active fish... please backing if there is any...
i think he is give or take a few to die ... bc i have had many fish and a couple of them did that and didn't label it in the end ...
Usually when a fish gets caught or approaching someone taps on the glass it puts them in shock, or it can even confer them brain damage. If hes going sideways more than likely hes going to die.
Answers:    aw i feel unpromising for him he keeps getting hurt. its a possiblilty he is dying cause he might have hurt himself when he get stuck in the plant so he might not be able to swim. he might of got stuck surrounded by the filter when he was trying to swim to the top. i think u should put him in a separate bowl beside just water in it, in need the other fish, and give him food and see if it can swim up to the top to eat it only to test and see if thats the problem.
Maybe he's injured. =/

Sorry about your fish. :(
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