Two new uncommon polyunsaturated amino ketones, (6Z,9Z,12Z,15Z)-1-[(2-phenylethyl)amino]octadeca-6,9,12,15-tetraen-3-one (1) and (6Z,9Z,12Z,15Z)-1-(diethylamino)octadeca-6,9,12,15-tetraen-3-one (2), were isolated from the Gangxi sponge Haliclona sp. The structures of new compounds 1 and 2 were determined by detailed analysis of their 1D-and 2D-NMR spectra, and high-resolution mass spectrometry.