Deanasue is right he doesn’t look good :/ If the tank is newly set up it could have been ammonia or nitrites. These are toxic to fish !! Moony42 is also correct maybe the fish been trapped :(:(:(
I have to agree with @Guppylover3x
It clearly will irritate the fish. Even with it being toxic, anything toxic will irritate the fish. It’s practically the same thing. You have received some very good advice.
I don’t think this fish will appreciate being kept in a tank. He/she probably feels very alone and isolated and probably has done since put in the tank. Anything self caught should be in the wild I think personally myself. These fish are not supposed to be kept in tanks. The fish probably misses...
Congratulations on the win! Where is guppylover3x’s tank of the month banner? It appears the users name was also spelt incorrectly in both TOTM posts. I can’t wait to see next months entries!