Charcoal fire is the same word used in 18.18; it occurs nowhere else in the New Testament.

The word used for fish is the same word used in 6.9,11. Although in Chapter 6 the word seems to have the meaning “dried fish” or “pickled fish,” in this and the following verse the reference is evidently to the fresh fish which had just been caught. The English word fish may be either singular or plural when applied to food, but the Greek text uses a singular here (New American Bible “a fish”). It is possible to understand the Greek text to mean that both the fish and bread were on the fire, but most translations indicate that only the fish were being cooked.

Quoted with permission from Newman, Barclay M. and Nida, Eugene A. A Handbook on the Gospel of John. (UBS Handbook Series). New York: UBS, 1980. For this and other handbooks for translators see here .