  We provide two 1-parameter families of indecomposable entanglement witnesses
in C4 {\otimes} C4. Following recent paper by Ha and Kye [Phys. Rev. A 84,
024302 (2011)] we show that these EWs are optimal and hence provide the
strongest tool in entanglement theory to discriminate between separable and
entangled states. As a byproduct we show that these EWs detect quantum
entanglement within a family of generalized Horodecki states.
