Discus should really be kept in a species only tank - some possible tankmates (due to the higher temperature required/different water parameters) are certain Corydoras and Cardinal Tetras (really wouldn't combine them with Yellow Labs, very messy ending).
Africans + Discus = Dead discus fat africans. africans ae aggressive and are kep in LARGE numbers to keep aggression down were as some disus are kept with peaceful and high tempreture liking fishsuch as corydas and cardinals. there are hundreds of tankmates avaliable for discus just lok around the forum.
hi,
labidochromis caeruleus, or yellow lab are from a different continent, need different water type, life style. their mbuna, from malawi, africa ,love rocks and rock hard water, over crowding, boisterous, graze algae, completely different needs to the discus, so no you cant mix the two. are they what you have in your tank now, mbuna