How long does fish sauce or oyster sauce last once opened?

Thanks!!

Likewise, my bottle lasted about 4 years (in the fridge) and I only tossed it out due to guilt of keeping it so long.

I've once had a bottle of fish sauce for several years (4 or 5 years). Never went bad. No need to refrigerate.

Oyster sauce, I do keep in the fridge. Never had a bottle for longer than a year so I don't really know if it's good or not after a year.

I'll echo nutcakes here. The sugar level in the Oyster Sauce will allow to last a very long time one to two year sounds like. As for the fish sauce, the salt level in it will allow to last as long as you, maybe longer. Keep both in the refrigerator for the maximum shelf life.

I use StillTasty.com for such questions (someone here mentioned it.) but it is my understanding that Fish Sauce lasts indefinately. I'd keep the oyster sauce a year or two, then replace.