Help on countercurrent systems in fish!

[gabbym]

In a countercurrent flow system, what happens to oxygen diffusion when there is no concentration gradient?

All i know is that the answer is has to be different than the one about a concurrent flow (which is that diffusion can not occur).
So im guessing that diffusion does still occur?

wow im lost. please someone help me!

[AstusAleator]

If there is no concentration gradient then there is no diffusion. period.

[mith]

The currents system simply makes it more oxygenated compared to other systems, but if there is no gradient no system will have any effect.

[Darby]

The point of a countercurrent system is to maximize the gradient along the blood flow, so the two parts of the question don't really go together.