Since, loss in weight of the body in the liquid is equal to the weight of the liquid displaced by the immersed part of the body which is equal to Vσ g, where σ is the density of liquid and V is the volume of the body immersed completely in the liquid.
Since, density of tap water is less than that of sea water.
Hence, loss of weight is more in case when the body is fuly immersed in sea water as compared to that of tap water.