Fresh water bony fishes maintain water balance by_.

Explanation

The correct answer is: Excreting a hypotonic urine. Freshwater bony fishes live in an environment where the water is less salty than their body fluids. This causes water to constantly enter their bodies through osmosis. To maintain osmotic balance and prevent their body from becoming overly diluted, they excrete large amounts of dilute urine. This process helps them eliminate excess water.Option A is incorrect because freshwater bony fishes absorb, rather than excrete, salt through their gills to compensate for the low salt concentration in their environment. Option B is incorrect because drinking water is not necessary; water naturally enters their bodies from the environment. Option D is incorrect because uric acid excretion is a method used by animals that need to conserve water, unlike freshwater fish that are constantly gaining water.