Greetings in The Lord, all.
For the Coptic tradition, there are 3 or 4 'degrees' of fasting, depending on how you would be dispensated; As a general and very central rule, fasting can only be taken seriously if it is guided by an elder to help you on the way so fruits may actually result instead of the harms that can arise from unguided fasting.
first degree fasts are Great Fast (Lent), Wednesdays and Fridays(all throughout the year except in the Holy Fifty(Eastertide), and if Theophany or Nativity fall on wed. or fri.), and Nineveh's Fast (3 day fast, always 2 weeks before Lent begins). Generally abstinence is to be observed until sun set(i have heard a muslim scholar tell me once that muslims took on this practice for their month of Ramadan), then vegan food is only allowed; no dairy, no seafood during these fasts, veg oil is always allowed but generally people never use it during holy week and the stric do not use it on wednesdays and fridays.
Second degree fasts are Nativity (advent) and Apostle's fast (this fast can vary in length since it depends on the amount of days between Holy Pentecost and and July 12th(feast day of Sts Peter and Paul). Traditionally these fasts never had allowed fish or seafood in them, but they do now, but Papa Shenouda frowns at any use of fish and seafood during fasts(as was the slightly older tradition).
Then of course there is Dormition fast, which most people fast first degree(Axion Esteen indeed, mostly holy Theotokos!) out of their love for the Theotokos, but the church does present it as a second degree fast(abstinence is not required till sunset).
Again, all of this is general/minimal rule, akrivia is dispensated depending on the level of the faster and the wisdom of the spiritual guide.
an interesting side point regarding the use of oil in the Greek tradition however! A professor of mine, his late father of blessed memory was a teacher at the Thessalonika school of theology, and he once told me that the latter told him the oil was restricted on the 'holier' days since it used to be stored in oilskins, thus veg oil was viwed as something contianing animal substance because it was stored in animal skins. I find tha kinda cool and wanted to share it.
rememeber me in your prayers,