Plecos and african cichlids would never meet in the wild if im correct. Can it be done? Absolutly. Should you? Probably not. Its one of those things that some people do but really shouldnt Bristlenose plecos are most commonly kept with african cichlids.. And again, People keep plecos as algae eaters. A lot of african cichlids are algae grazers to begin with. So dependent on the type of african cichlid it is. It may not even be nessasary
Also if its your oscar that your refering as an 'african cichlid' its actually a south american cichlid
If thats the case then a larger pleco such as a common pleco or gibbiceps/sailfin then they in fact CAN be kept together
Although these larger fish need much more space as said above