This is a guideline about fishing in the Fjords in Norway.
We will break it down to fishing from the kayak and fishing from the shore. As fishing from shore is available at any time.

TIME
Fishing is time-consuming, so make sure you have enough patience and time to commit. While you might get lucky instantly, generally, you’ll need a few hours. Fish are also most active in the early morning and evening.
WEATHER
Fish are extremely aware of atmospheric pressure changes. When the weather changes rapidly—like before a storm—fish get confused and prioritize adjusting their body pressure over eating. The best time is typically a calm, cloudy day (low pressure), but sunny days (high pressure) can work too. The main thing to avoid is very windy conditions, as the fish likely won’t bite, and kayaking stability will suffer.
TIDE
Fish generally follow tidal patterns. A rising tide pulls more nutrition and baitfish into the fiord, this is making fish more active. This means you’re more likely to catch fish in faster currents (like behind rocks) rather than during total slackwater. While this is less critical in the Lysefjord than in places with stronger currents, it can still makes a difference.
Mackerel (Makrel)
Mackarel is active, fast and strong for it’s size. Usually found scanning coastlines in big bay areas for small fish. You will notice what looks like illogical current lines in the water if you are paying attention but that is really big stims of Mackarel moving around looking for food. Can also be found out in the middle of the fiord in superdeep water. Less likely but it is one of the few fish you can get by trolling in the middle of the fiord since they often swim quite close to the surface.

Cod (Torsk)
Fish that like to hang out at the bottom close to seaweed or steep cliffsides, generally quite slow. Normally hangs out in rocky areas with a lot of hiding opportunities.

Pollach (Lyrtorsk)
Probably the most common fish to get in Lysefjord in Norway. Lives near and in slanting rocky hills going down in the water and also on steep cliffsides.
Generally quite similar places that Cod hangs out in but will go further out from their hiding in the rocks and hunt in open water which makes it easier to catch them with fishing rods from shore.

Atlantic salmon (lax)
Those are very difficult to catch in the ocean and are low in population, and should be carefully released back if caught unless you know the specific standards so that they are legal to take them with you.

To fish from shore, it is best to grab a rod that can cast 15-60g lures, preferably bought from a store. Keep costs down by starting with cheap 25g lures due to fishing gear gets expensive fast!
Invest more only once you know it’s your new hobby.
Once equipped, head to any rocky shoreline. The easiest fish to start catching are Pollach or Mackerel.
You have two main options for shore fishing:
Use a single lure, typically spoon-like or a smaller imitation of a fish.
Use a tackle similar to the handline rigs. This gives you a shot at catching up to six mackerel in a single cast if you hit a school.
Trolling is fishing while paddling. There are two ways:
Bottom Trolling (Slow): Use a red weight and jigging tackles. Paddle slowly, trying to keep the weight bouncing on the seabed. Do not use a pilk bait; it will snag.
Surface/Mid-Water Trolling (Fast): Use a lighter weight (75-125g pilk or red weight) and paddle faster. Use lures like silver spoons or small, shiny lures to target active fish near the surface (like mackerel).
Casting from a kayak is the most difficult method, usually done with a handline or rod. While it allows for precision, reeling in a big fish on a rod from a kayak feels unsafe. It can work for specific surface targets like seatrout or salmon, but is best left for shore fishing.
As with everything else, how you fish depends on what you are fishing for.
Depending on how deep you want to fish and what kind of fish you are looking for, you will have to shift between these ways to find the best luck with catching fish.