get blue gloves. they will be easier to see if you accidentally cut off a bit of them and need to retrieve it from the food

They aren’t cut proof by any means but they will help with the smell on your hands.

I work in environmental/hazardous waste investigation and remediation. The color of the nitrile gloves doesn't make a difference in the chemical resistance of them. A sharp hook or knife will go through the nitrile just as readily as your skin. I recommend buying nitrile coated cut resistant gloves. These are made of fabric with kevlar strands woven through them and then dipped in nitrile primarily for grip. You can wear standard nitrile gloves underneath them for chemical/smell protection. The kevlar woven gloves are good for accidental slips with a sharp object but may not stand up to intentional cutting/puncturing. There are different grades of cut and puncture resistance depending on the weave.

As another commenter noted they come in different thicknesses. I think they also vary in quality, and the quality fades with age. I got some mechanic gloves which tore if you looked at them but they were thick. I’ve got some surgical gloves you can practically stab with knife and not puncture and they’re thin.

Your reasons for using gloves are good, but I have a pet peeve about people using gloves as a panacea (likely inflamed by people using them during covid). When you’re using gloves for cooking, every time you would wash your hands is a time you need to change gloves. That means you need to change gloves a lot. I almost never see people changing out with the frequency that’s necessary.

People who work selling fish wear latex gloves, the same ones for washing dishes, that you can buy at the supermarket for a euro.

Black are usually thicker, so they last longer.

Medical is blue so that a single drop of blood is highly visible, and to be changed often to prevent contamination.

Black was used for the opposite reason, easy to hide stains and thicker so that they can be worn longer or even taken off and put back on.

Because black was thicker it was more expensive....

So people started selling thin black ones, and now color doesn't matter. You need to pay attention to thickness, and it really doesn't matter.

If you're worried about cuts get safety gloves and put them on over the nitrate gloves. You don't need one on your knife hand.

The color doesn't make any difference with how the gloves function. The color is aesthetic or in some cases, organizational, e.g. green for food handling and blue for medical.

Nitrile gloves come in different thicknesses, which changes how strong they are and how tactile. For food handling, the thinnest 2-3mm is usually fine; you still get good feeling through them and they're cheap so you can swap them out to avoid cross contamination.

If cutting fish, you may want slightly thicker gloves, like 4-5mm or 6-7mm, so they hold up better. But if solely for smell/fluids contact, the 2-3mm should do you.