Often while I’m cooking I also have a stockpot going. I feed it with bits and pieces of whatever I have at hand. It can be the end of a carrot, a head of a fish or bones from a piece of meat etc. My vegetable stock as described in the diagram, can be made just as shown or together with any kind of meat. The point is to use the parts of vegetables or meat that you normally don’t eat. However the ingredients must be fresh! With fish I would add some dill stalks and maybe lemon rinds.
I use my stocks to feed risotto, soups, cook beans in or to touch up stews. The use is really endless.