Nidaliidae is a family of soft corals in the phylum Cnidaria. Some members of this family are similar in appearance to gorgonians (sea fans). They are difficult to keep in the reef aquarium because they do not contain symbiotic zooxanthellae and therefore need to be fed on zooplankton. Others, in the genera Agaricoidea, Nidalla and Pieterfaurea, more resemble members of the family Nephtheidae and these are somewhat easier to keep in the aquarium.