5d theories can be at fixed points, in many cases exhibiting rather amusing properties. In this talk we will study several properties of these fixed point theories. In particular, we will describe how to put them supersymmetrically in curved spaces. As a consequence, we will discuss when a deformation to a Yang-Mills theory is possible. The latter typically exhibit a smaller global symmetry that that of the fixed point theory, which, from the YM point of view, appears as an enhanced symmetry. In this enhancement instantons play a pivotal role, and we will discuss several aspects of these.