Given a constant $$k>1$$
k
>
1
, let Z be the family of round spheres of radius $${{\,\mathrm{artanh}\,}}(k^{-1})$$
artanh
(
k
-
1
)
in the hyperbolic space $${\mathbb {H}}^3$$
H
3
, so that any sphere in Z has mean curvature k. We prove a crucial nondegeneracy result involving the manifold Z. As an application, we provide sufficient conditions on a prescribed function $$\phi $$
ϕ
on $${\mathbb {H}}^3$$
H
3
, which ensure the existence of a $$\mathcal{C}^1$$
C
1
-curve, parametrized by $$\varepsilon \approx 0$$
ε
≈
0
, of embedded spheres in $${\mathbb {H}}^3$$
H
3
having mean curvature $$k +\varepsilon \phi $$
k
+
ε
ϕ
at each point.