Many non-Japanese conflate sashimi and sushi; the two dishes are actually distinct and separate. Sushi refers to any dish made with vinegared rice, and while raw fish is one traditional sushi ingredient, many sushi dishes contain seafood that has been cooked, while others have no seafood at all.
It's the moisture and contaminents that break down the DOT 3 and 4 fluids which is the reason to change the fluid in the first place. If you don't change it, what happens is moisture enters the system via the vented fill caps on the brake master cylinder. This moisture along with dust, mixes and travels in the system eventually making it's way to the lowest points in the system.
Water in your brake fluid will lower you effective boiling point and degrade your entire systemâs performance. If you have air in your brake lines, this will also degrade your system since the air will compress easier than the fluid would have, thus less energy is applied to the clamping force on the rotor. This is why it is important to keep fresh, high-quality fluid in your system and make sure all air is properly bled out.