These are Orthodox monks, so their fasts are different than Catholic rules (as is their calendar). As I recall from Grandma, it's an escalating fast, and different rules for different weeks. I never could keep her rules straight.
Until last week we were allowed fish. I think we are currently allowed olive oil and wine (my wife keeps track for us). Starting the 20th, it's just vegan fare. The 24th is no food or water at all, for those who are able.
That said, we are warned against being "Holier than thou." I have no idea what disciplines the monks follow and it is really not my business.
I have heard stories of monks eating meat whenever visitors arrived, both to show hospitality and so it does not appear they are showing off their ascetic practices.