  Millimeter-sized Ce$_2$Rh$_{3+\delta}$Sb$_4$ ($\delta\approx 1/8$) single
crystals were synthesized by a Bi-flux method and their physical properties
were studied by a combination of electrical transport, magnetic and
thermodynamic measurements. The resistivity anisotropy
$\rho_{a,b}/\rho_{c}\sim2$, manifesting a quasi-one-dimensional electronic
character. Magnetic susceptibility measurements confirm $\mathbf{ab}$ as the
magnetic easy plane. A long-range antiferromagnetic transition occurs at
$T_N=1.4$ K, while clear short-range ordering can be detected well above $T_N$.
The low ordering temperature is ascribed to the large Ce-Ce distance as well as
the geometric frustration. Kondo scale is estimated to be about 2.4 K,
comparable to the strength of magnetic exchange. Ce$_2$Rh$_{3+\delta}$Sb$_4$,
therefore, represents a rare example of dense Kondo lattice whose
Ruderman-Kittel-Kasuya-Yosida exchange and Kondo coupling are both weak but
competing.
