  Cluster galaxies are affected by the surrounding environment, which
influences, in particular, their gas, stellar content and morphology. In
particular, the ram-pressure exerted by the intracluster medium promotes the
formation of multi-phase tails of stripped gas detectable both at optical
wavelengths and in the sub-mm and radio regimes, tracing the cold molecular and
atomic gas components, respectively. In this work we analyze a sample of
sixteen galaxies belonging to clusters at redshift $\sim 0.05$ showing evidence
of an asymmetric HI morphology (based on MeerKAT observations) with and without
a star forming tail. To this sample we add three galaxies with evidence of a
star forming tail and no HI detection. Here we present the galaxies $\rm H_{2}$
gas content from APEX observations of the CO(2-1) emission. We find that in
most galaxies with a star forming tail the $\rm H_{2}$ global content is
enhanced with respect to undisturbed field galaxies with similar stellar
masses, suggesting an evolutionary path driven by the ram-pressure stripping.
As galaxies enter into the clusters their HI is displaced but also partially
converted into $\rm H_{2}$, so that they are $\rm H_{2}$ enriched when they
pass close to the pericenter, i. e. when they develop the star forming tails
that are visible in UV/B broad bands and in H$\alpha$ emission. An inspection
of the phase-space diagram for our sample suggests an anticorrelation between
the HI and $\rm H_{2}$ gas phases as galaxies fall into the cluster potential.
This peculiar behaviour is a key signature of the ram-pressure stripping in
action.
