We continue studying the -Ricci vector field on a Riemannian manifold , which is not necessarily closed. A Riemannian manifold with Ricci operator T, a Coddazi-type tensor, is called a T-manifold. In the first result of this paper, we show that a complete and simply connected T-manifold, , of positive scalar curvature , admits a closed -Ricci vector field such that the vector is an eigenvector of T with eigenvalue , if and only if it is isometric to the m-sphere . In the second result, we show that if a compact and connected T-manifold, , admits a -Ricci vector field with and is an eigenvector of a rough Laplace operator with the integral of the Ricci curvature that has a suitable lower bound, then is isometric to the m-sphere , and the converse also holds. Finally, we show that a compact and connected Riemannian manifold admits a -Ricci vector field with as a nontrivial solution of the static perfect fluid equation, and the integral of the Ricci curvature has a lower bound depending on a positive constant , if and only if is isometric to the m-sphere .