A system for centralised water monitoring of a fish farm, the system comprising a plurality of fish tanks divided into a first and a second subgroup； and a first sample conduit (08) only connected to the first of the subgroups through a first set of pipe connections, and a second sample conduit (10) connected only to the second of the subgroups through a second set of pipe connections； each one of the pipe connections being connected to only one fish tank； the pipe connections being configured for water sampling from a selected fish tank of the first subgroup (04) into the first sample conduit (08) and from a selected fish tank from the second subgroup (06) into the second sample conduit (10). Water samples are received by a first and second sensor system (26, 24) from the first and second sample conduits for simultaneous measurements of the samples by the sensor system (26, 24).
