Oscar Aggression

[StylinT]

hey all im having alot of problems with my 2 oscars the last week or so i have them in a 100 gallon tank with a jack dempsey an 2 plecos an it has been liek this for months an now all of a sudden my oscars are causing havek in the tank chasing my plecos an jack an when i go to clean or move stuff in the tank the one oscar bites me (which hurts) they are about 7 - 8 inches long an i dont knwo what to do to deal with the agression
any help is Good