  Precise thermal expansion and magnetostriction studies of the intermetallic
compound Eu$_2$CuSi$_3$ in the temperature range between 5 and 300 K are
presented. A clear sign of magnetic second order phase transition at the
ferromagnetic Curie temperature $T_{\rm C}$ = 34 K indicates strong
magneto-structural coupling. Uniaxial thermal expansion data show a large
anisotropy between the magnetic easy $c$-axis and the hexagonal $ab$-plane,
which is associated with a strongly anisotropic magnetic coupling. A
spin-reorientation regime as well as a non-uniform energy scale are indicated
by Gr\"uneisen analysis of the data at low temperatures. Anomalous
contributions to the thermal expansion imply ferromagnetic correlations far
above in zero magnetic field. The magnetic phase diagram is constructed,
showing the evolution of short- and long-range magnetic order in magnetic
fields up to 15 T. The anisotropic magnetic field effect yields anomalous
magnetostrictive effects up to about 200 K.
