Managing Cooking Oils

I'm recently buying and cooking with some expensive oils. Like walnut and coconut oil.

I'm wanting to deep fry and pan fry using a fryer and a black skillet.

What's the best thing to do when done cooking to be able to utilize the same oil?

With cheap oils like corn, canola, sunflower I generally was just tossing it out because they were so inexpensive.

I'm also assuming once you've used a batch in a skillet for a fish that oil is probably not able to be used again.

I'm a bit surprised that you may want to use any of these oils for general cooking or frying, unless you do a lot of Indian recipes that require coconut oil. To me walnut oil is better used cold as a fragrant component of a special salad dressing. Or to carefully pan-roast for a very brief time walnut pieces for various recipes and cakes.
All I can suggest is the method we used in my native France when we fried frenched potatoes (frites) in peanut oil. By the way peanut oil is to me the best oil for sauteing and deep frying.
We filtered the oil after frying in a conic coffee paper filter inserted into a fine mesh metal sieve,or even directly into the sieve, and pour it in a clean glass jar with a metal lid (like a Ball jar). We would wait until the oil was cold, make sure that the lid was tightly closed, and store the oil in the refrigerator (lower level). We could use that oil 3 or 4 more times during a 3 months period.
Some people would throw a raw egg white in the frying pot or pan while the oil was still hot in order to coalesce all the tiny burned fried food debris in on single spot on the surface of the oil as an easy way to get rid of them before preserving the oil.

Thanks for your reply.

I had some hand made tofu and chose to tempura batter it. I used coconut oil to fry it in. Great taste.

I'll try the egg thing and get some Ball jars.