Can mono not accompanied with a fever?

Possible: Not all mono infections are accompanied by a fever.

Probably not: Good to know facts about this infectious disease. So many rumors fly around the "kissing disease". It is known to be spread by saliva. There is a definitive test -monospot test - to DX it. A dr does an exam, if concerned they run the test. Don't diagnose yourself. Here's some good info - if you're still unsure you don't have it - see a doctor. https://www.ncbi.nlm.nih.gov/pubmedhealth/pmh0001617/.