  The results of three different searches for neutrino candidates, associated
with the IceCube-170922A event or from the direction of TXS 0506+056, by the
ANTARES neutrino telescope are presented. The first search refers to the online
follow-up of the IceCube alert; the second is based on the standard
time-integrated method employed by the Collaboration to search for point-like
neutrino sources; the third uses the information from the IceCube
time-dependent analysis reporting a bursting activity centered on December 13,
2014, as input for an ANTARES time-dependent analysis. The online follow-up and
the time-dependent analysis yield no events related to the source. The
time-integrated study performed over a period from 2007 to 2017 fits 1.03
signal events, which corresponds to a p-value of 3.4% (not considering trial
factors). Only for two other astrophysical objects in our candidate list, a
smaller p-value had been found. When considering that 107 sources have been
investigated, the post-trial p-value for TXS 0506+056 corresponds to 87%.
