  In the present paper, we study the dynamics of a nine compartmental
vector-host model for Zika virus infection where the predatory fish Gambusia
Affinis is introduced into the system to control the zika infection by preying
on the vector. The system has six practically feasible equilibrium points where
four of them are disease-free, and the rest are endemic. We discuss the
existence and stability conditions for the equilibria. We find that when sexual
transmission of zika comes to a halt then in absence of mosquitoes infection
cannot persist. Hence, one needs to eradicate mosquitoes to eradicate
infection. Moreover, we deduce that in the case of zika infection pushing the
basic reproduction number below unity is next to impossible. Therefore, O_0,
the mosquito survival threshold parameter, and O, the mosquito survival
threshold parameter with predation play a crucial role in getting rid of the
infection in respective cases since mosquitoes cannot survive when these are
less than unity. Sensitivity analysis shows the importance of reducing mosquito
biting rate and mutual contact rates between vector and host. It exhibits the
importance of increasing the natural mortality rate of vectors to reduce the
basic reproduction number. Numerical simulation shows that when the basic
reproduction number is close but greater than unity, the introduction of a
small amount of predatory fish Gambusia Affinis can completely swipe off the
infection. In case of high transmission or high basic reproduction number, this
fish increases the susceptible human population and keeps the infection under
control, hence, prohibiting it from becoming an epidemic.
