Summary: We use the tanh method for solving several forms of the fifth-order nonlinear Korteweg-de Vries (KdV) equation. The forms include those of

*P. D. Lax* [Commun. Pure Appl. Math. 21, 467–490 (1968;

Zbl 0162.41103)],

*K. Sawada* and

*T. Kotera* [Prog. Theor. Phys. 51, 1355–1367 (1974;

Zbl 1125.35400)],

*D. Kaup* [Stud. Appl. Math. 62, 189–216 (1980;

Zbl 0431.35073)],

*B. A. Kupershmidt* [A super KdV equation: an integrable system, Phys. Lett. 102A, 213–215 (1984)],

*M. Ito* [J. Phys. Soc. Jpn. 49, 771–778 (1980)], and other related special cases. Abundant solitons solutions are derived. Two necessary criteria are established to build up reliable strategies that govern the relation between the parameters of the equation. Previously known solutions are recovered and entirely new bell shaped solitons are determined.