Fish accelerates, weight, 2/3 length what is F in Newtons (N)?

Question

A fish has a length of 1.5 m and a mass of 63 kg.
It accelerates from 3.0 m/s to 6.3 m/s.
Assume there is no drag force.
F is exerted until 2/3 of the fish's length has left the water.
What is the magnitude of F? In Newtons (N)?

Answer 1

v1^2-v0^2=2*a*x
v1=6.3
v0=3
a=?
x=2/3*1.5=1m
==>
a=15.345
f=m*(a+g)
f=63*(15.345+9.81)=1584.765N

Answer 2

You cannot calculate F = ma with the data given, you need the amount of time it takes to emerge 2/3 from the water.