Pleco didnt make it HELP PLZ!

[zombiz]

Got home from work and found my pleco dead ( R.I.P Prometheus )

Can someone identify what is on him so i can treat it and hopefully save the others, no other fish is showing any sighs or symptoms but my rainbow shark is acting kinda odd, i dont know if hes sick or because i took all the fish out accept him and the plecos.

Aquarium Advice - Aquarium Forum Community - zombiz's Album: Possibly sick - Picture

Aquarium Advice - Aquarium Forum Community - zombiz's Album: Possibly sick - Picture

Aquarium Advice - Aquarium Forum Community - zombiz's Album: Possibly sick - Picture

 

[Fishie]

What's you water parameters?? Is your tank cycled? Any bullies? Tank mates?