Neon Tetra With Moving Lump

[ReiRei]

Currently have a Neon Tetra sitting at the bottom of the tank with a triangular bulge. Weird thing is that the buldge will dissapear, and grow again within seconds, and will keep doing that - like it's got something inside it.
 
60litre tank, Pearl Danios, Neon Tetra, Betta

 

[laurac94]

Parasites? I would suggest quarantining the fish immediately so it does not spread to other fish, if this is an option ;-)
Could be some type of worm, not really come across this problem before.

 

[TallTree01]

I agree: Quarantine it. Maybe give it salt baths?