From the Large Typicon, chapter 32:

Let it be known, that during the lents of the Holy Apostles, Nativity of Christ, and Dormition of the Holy Theotokos, on Tuesdays and Thursdays fish is not allowed. [On those days] only food with oil and drinking wine is allowed. On Monday, Wednesday, and Friday we do not eat neither fish or food with oil, but we fast until the 9th hour and consume food once a day with raw foods.

From the same typcion, chapter 34:

During the fasting periods before the feasts of the Holy Apostles or the Nativity of Christ, fish is not to be consumed other than on Saturdays and Sundays. However, laypeople can eat fish on Tuesday, Thursday, and weekends twice a day.

Nomocanon, rule 223:

Durings the lents of the Holy Apostles, Nativity of Christ, and the lent of the Holy Theotokos, we eat raw food three times a week: on Monday, Wednesday, and Friday. On those days we abstain from eating fish, food with oil, and drinking wine, except in the cases of sickness of feebleness. On those days we consume Sochivo (refers to foods without oil), just like during the first 5 weeks of the Great Lent. Those, who want to please God, eat fish and food with oil only on Saturdays and Sundays.

Typicon of the Solovestky Monastery:

During the lent of the Holy Apostles, as well as during the Nativity lent before the feast of St. Nicholas, we eat fish on Tuesdays and Thursdays once a day, on Saturdays and Sundays twice a day.

Matthew Blastares, compilation 800, and rule 19 of Patriarch Nicephorus:

During the lents of the Holy Apostles and St. Philip, monastics are ought to eat once a day in the evening on Wednesdays and Fridays. However those who engage in physical labor can eat twice a day: after the 6th hour and then later in the evening.