What is the volume of a fish swimming in seawater if a buoyancy force of 10.3 N acts on it?

The buoyancy force, i.e. the Archimedes force is directly proportional to the density of the fluid, the acceleration of gravity and the volume of the submerged body:
Fa = p * g * V
V = F / p * g = 10.3 / 10 = 1cm ^ 3

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