###### Abstract  
This paper studies the combined effects of viscous dissipation, first and second-order slip and variable transport properties on phase-change hydromagnetic bio-nanofluid convection flow from a stretching sheet. Nanoscale materials possess a much larger surface to volume ratio than bulk materials, significantly modifying their thermodynamic and thermal properties and substantially lowering the melting point. Gyrotactic non-magnetic micro-organisms are present in the nanofluid. The transport properties are assumed to be dependent on concentration and temperature. Via appropriate similarity variables, the governing equation with boundary conditions are converted to nonlinear ordinary differential equations and are solved using the BVP4C subroutine in the symbolic software MATLAB. The non-dimensional boundary value features a melting (phase change) parameter, temperature-dependent thermal conductive parameter, first as well as second-order slip parameters, mass diffusivity parameter, Schmidt number, microorganism diffusivity parameter, bioconvection Schmidt number, magnetic body force parameter, Brownian motion and thermophoresis parameters. Extensive computations are visualized for the influence of these parameters. The present simulation is of relevance in the fabrication of bio-nanomaterials for bio-inspired fuel cells. m pacs: 97.10.Kc, 97. In the most general case, the melting heat transfer problem is a moving boundary problem, and powerful computational methods are necessary for a solution (adaptive grid methods, volume-of-fluid methods, front tracking methods, phase field approaches etc.). An alternative approach is, however, to focus on boundary-layer flow in melting phase-change problems in which the melting effect can be simulated as a boundary condition which circumvents the need to solve the full field equations in real time. Although less accurate, this approach has its merits since it does provide a reasonable approximation for the wall heat transfer rates. [PERSON] and [PERSON] [7] theoretically determined the effect of melting on heat transfer via convection between a body which is melting and the surrounding fluid. It was shown that melting has the effect of retarding heat transfer rate. [PERSON] and [PERSON] [8] investigated steady laminar flow over a flat plate in the case of melting heat transfer. They found that melting has the effect of inhibiting the rate of heat transfer and reducing the local Nusselt number. The Chebyshev spectral method was used by [PERSON] and [PERSON] [9] to compute solutions for melting stagnation point flow of a micropolar fluid in a permeable material with heat absorption effect, noting a reduction in surface shear stress with stronger melting effect and the reverse response in the local Nusselt number. [PERSON] [10] employed the lattice Boltzmann method to solve the problem of slip flow in a microchannel of a copper, silver and aluminium oxide with water-based nanofluid. [PERSON] et al. [11] investigated phase-change forced convection flow from a metal plate in porous regime, noting the strong influence of melting parameter on the local heat transfer rate at the melt interface with the solid. [PERSON] [12] obtained perturbation solutions for phase-change convection in swirling flow from a disk, observing a significant modification in temperature, velocity, torque and wall heat transfer with the ratio of injection (melt) rate and viscosity parameter. [PERSON] et al. [13] computed solutions for magnetohydrodynamic melting flow and convection from a planar spinning disk, identifying that the melt rate for which a steady state solution exists is reduced with stronger magnetic field. [PERSON] et al. [14] used the D2Q9 Lattice Boltzmann method (LBM) to study numerically the free convection melting with radiative heat transfer applied to solve the coupled heat transfer during phase change process involving natural convection and radiation.