腐生 is read as ふせい (fusei) and means saprophagy.
ふせい
fusei
ふせいどうぶつ
saprozoa
ふせいしょくぶつ
saprophytic plant
ふせいきん
saprophytic fungus
いきぐされ
(fish) appearing fresh but actually gone bad
ふはい
corruption
くさる
to lose a bet
ふしょく
saprophagy
ふしん
taking great pains (to do)
ふようど
humus
くさり
rottenness
ふらん
decomposition
ふしゅう
smell of something rotten