Mulch: "Now that you're a fishing pro, I'm sure you'll be coming around the waters here more often. You'll come across many animals and plants, so you should be familiar with how the food chain works! Go talk to Phlegma."
1- Talk to Phlegma
Phlegma: "You're interested in plants? Good! Most food chains start with plants. Well ... technically, the sun. Sunlight is important for plants to make their own food for energy. That's why my Greenhouse has a sunroof! Talk to Ruffnut by the Hatchery to see if she knows about the algae plants in the lake!"
2- Meet Ruffnut
Ruffnut: "Hey! Of course I know about algae! It kind of stinks sometimes, but the mosquitoes love it. Yuck! The males are herbivores; they only eat plants. The females are omnivores; they feed off of plants and animals. If you go to the lake, you'll see fish jumping! Mulch knows more about that!"
3- Meet Mulch by the Lake
Mulch: "Nice to see you back, [Your Viking's Name]. The fish are really active out there today eating those mosquitoes. The funny thing is, fish also eat breadcrumbs and worms. That's why we can use those things as bait. Fish are omnivores because they eat both plants and animals. Now why don't you catch a fish and feed your dragon?"
4- Catch a fish
Mulch: "There you go! Once you feed this fish to your dragon, this food chain will be complete!"