  We present the results of a systematic search and characterisation of
jellyfish galaxy candidates in the multi-cluster system A901/2, at z ~ 0.165,
as part of the OMEGA survey. By visual inspecting ACS/HST F606W images looking
for morphological signatures of ram-pressure stripping events in
Halpha-emitting galaxies, we identify a total of 70 candidates. Out of these,
53 are clearly star-forming galaxies and 5 are highly probable AGN hosts, the
classification of the remaining galaxies is more uncertain. They have late-type
and irregular morphologies and most of them are part of the blue cloud with
only 4 being previously classified as dusty reds. The AGN activity is not
prominent in the sample and, of the few cases of galaxies hosting AGN, such
activity does not seem to be correlated to the gas stripping phenomenon. Our
jellyfish galaxy candidates do not have a preferential pattern of motion within
the multi-cluster system, although the most compelling cases appear to inhabit
the inner regions of the most massive sub-cluster centres. The sSFR of these
galaxies indicates that their star formation activity is enhanced, in contrast
with what is observed for the rest of the star-forming galaxy population in the
system. Half of the sample is forming stars at a higher rate than the
main-sequence for field galaxies and this behaviour is more evident for the
most compelling candidates. For some galaxies, the spatially resolved Halpha
emission appears to be as disturbed and extended as their continuum
counterparts. Our findings point towards a scenario where the ram pressure
stripping is triggering a period of intense and extended star formation
throughout the galaxy while it is also disturbing the morphology. This is the
largest sample of jellyfish galaxy candidates found in a single system
suggesting that cluster mergers might be the ideal environment for studying ram
pressure stripping effects.
