Accumulation of 2,4,6-trichlorophenyl-4'-aminophenyl ether (CNP-amino) in carp was investigated for 14 days. CNP-amino in carp could be divided into free CNP-amino [CNP-amino(I)] and bound CNP-amino [CNP-amino(II)]. 2. The bioconcentration factors (BCF) of CNP-amino(I + II) in carp were 90 +/- 38 (mean +/- SD, n = 3) for muscle, 402 for liver, 501 for kidney and 5368 for gallbladder after 14 days exposure. 3. 2,4,6-Trichlorophenyl-4'-acetamide phenyl ether (CNP-acetamide) was detected as metabolites of CNP-amino in muscle and viscera of carp.