I was wondering are mood disorders caused by fungus ?

No: Fungal infections generally do not affect mood, unless you are focusing on having a fungal disease and that is bringing you down. Mood disorders are mostly caused by abnormalities or changes in brain chemistry. See a psychologist or a psychiatrist for help with those problems. An Infectious Diseases doctor can help if there is a fungal infection present.

There is: no scientific evidence of a causal linkage to fungal infections , but being sick with any illness can certainly affect your mood.