We consider the coupled chemotaxis–Navier–Stokes system with logistic source term
{nt+u⋅∇n=Δn−∇⋅(n∇c)+rn−μnα,ct+u⋅∇c=Δc−nc,ut+(u⋅∇)u=Δu+∇P+n∇Φ,∇⋅u=0
in a bounded, smooth domain Ω⊂ℝ3, where Φ∈W2,∞(Ω) and where r≥0, μ>0 and 1<α<2 are given parameters. Although the degradation here is weaker than the usual quadratic case, it is proved that for any sufficiently regular initial data, the initial-value problem for this system under no-flux boundary conditions for n and c and homogeneous Dirichlet boundary condition for u possesses at least one globally defined weak solution. And this weak solution becomes smooth after some waiting time provided 65≤α<2.