  This paper deals with the two-species Keller--Segel-Stokes system with
competitive kinetics $(n_1)_t + u\cdot\nabla n_1 =\Delta n_1 -
\chi_1\nabla\cdot(n_1\nabla c)+ \mu_1n_1(1- n_1 - a_1n_2)$, $(n_2)_t +
u\cdot\nabla n_2 =\Delta n_2 - \chi_2\nabla\cdot(n_2\nabla c) + \mu_2n_2(1-
a_2n_1 - n_2), c_t + u\cdot\nabla c =\Delta c - c + \alpha n_1 +\beta n_2$,
$u_t= \Delta u + \nabla P+ (\gamma n_1 + \delta n_2)\nabla\phi$, $ \nabla\cdot
u = 0$ under homogeneous Neumann boundary conditions in a bounded domain
$\Omega \subset \mathbb{R}^3$ with smooth boundary. Many mathematicians study
chemotaxis-fluid systems and two-species chemotaxis systems with competitive
kinetics. However, there are not many results on coupled two-species
chemotaxis-fluid systems which have difficulties of the chemotaxis effect, the
competitive kinetics and the fluid influence. Recently, in the two-species
chemotaxis-Stokes system, where $-c+\alpha n_1+\beta n_2$ is replaced with
$-(\alpha n_1+\beta n_2)c$ in the above system, global existence and asymptotic
behavior of classical solutions were obtained in the 3-dimensional case under
the condition that $\mu_1,\mu_2$ are sufficiently large. Nevertheless, the
above system has not been studied yet; we cannot apply the same argument as in
the previous works because of lacking the $L^\infty$-information of $c$. The
main purpose of this paper is to obtain global existence and stabilization of
classical solutions to the above system in the 3-dimensional case under the
largeness conditions for $\mu_1,\mu_2$.
