The headword -- which appears in the accusative case in the quotation given -- is unglossed here, but (with different accentuation) has a gloss in Hesychius ("bark of trees, or light wood"). According to LSJ, fello/s is Quercus suber, or something made of cork, such as floats on a fishing-net.
[1] Greek Anthology 6.192.5-6 (Archias); cf. beta 365, tau 1014. [Adler inserts the comma after fello/n, i.e. taking the "always" with what follows.] See further excerpts from this epigram, the dedication of a retiring fisherman, at gamma 54 and iota 68.