We're gonna need some more details. Tank size? Parameters? Tank mates? Filtration? Any other fish having problems? Also, check to see if he is already dead. Does the tank smell? You can just try lightly poking him to see if he moves.
Tank size 37 gallons, lives with other platys, mollys, dwarf gourami, neon tetras, rubberlip Pleco, Julii Corys. Parameters were perfect last time i checked. Filtration is good i have penguin biowheel 350. No other fish are having problems. He is dead i just wanted to know if there was anyway i could revive him. Thank you