A unified analysis of all existing solitary wave solutions - bright, black and gray - of the cubic-quintic nonlinear Schrödinger equation (CQNLSE) is made concretely, considering a monomode step-index optical fibre with third- and fifth-order nonlinearities in the anomalous dispersion frequency region. Different aspects of the effect of the fifth-order nonlinearity, such as the existence of bright and gray solitary waves in the same parameter range and dark solitary wave bistability are considered. The influence of the distributions modified by the nonlinearity radial fields on the quintic dispersion coefficient in the CQNLSE is calculated. The results obtained are applicable to the cases of spatial solitons and optical beam self-action in highly nonlinear media.