A vertical spring scale can measure weights up to $180$ N

$.$ The scale extends by an amount of $11\mathrm{.}0$ cm

from its equilibrium position at $0$ N

to the $180$ N

mark. A fish hanging from the bottom of the spring oscillates vertically at a frequency of $2\mathrm{.}85$ Hz

$.$ Ignoring the mass of the spring, what is the mass m

of the fish?