Under investigation in this paper is a generalized variable-coefficient fifth-order Kortewegde Vries equation, which describes the interaction between a water wave and a floating ice cover or the gravity-capillary waves. Via the Hirota method, Bell-polynomial approach and symbolic computation, bilinear forms, N-soliton solutions, Backlund transformation and Lax pair are derived. Infinitely-many conservation laws are obtained based on the Bell-polynomial-typed Backlund transformation. Soliton fusion and fission, and influence of the variable coefficients from the equation are analyzed: Both variable coefficients c(t) and n(t) are in direct proportion to the soliton velocities but have no effect on the amplitudes, while another constant coefficient a can affect the types of the interactions, in the sense of the elastic or inelastic. Elastic-inelastic interactions among the three solitons are presented as well. (C) 2016 Elsevier Inc. All rights reserved.