Tenochtitlan was built on an island in the middle of Lake Texcoco. The Aztecs didn't have any farmland, so they devised a way to create their own farmland, called chinampas.
The Aztecs wove giant reed mats and placed them on top of the water. They made a fence around the mat and placed mud, silt, and rotten vegetables on it. Then willow trees were planted on all sides of the chinampa. The willow trees grew very quickly and their roots bound the soil to keep it from washing away. The Aztecs planted corn, tomatoes, potatoes, chili peppers, and squash. The plants' roots would grow to the bottom of the lake so they would have an endless supply of water. The chinampas were manmade islands created by piling up mud and vegetation from the bottom of the lake. The size of the chinampas didn't matter; what mattered was if two canoes could pass between the chinampas. The mud that the Aztecs used to build the chinampas was rich in minerals and ideal for growing crops. Tomatoes, avocados, and chili peppers were unheard of in Europe until Spanish explorers brought some back from Aztec lands. The Aztecs didn't use any plows or any wheel-driven vehicles at all; they only needed and used a simple wooden digging stick and a wooden hoe for growing and harvesting crops.
Fishermen made fishing nets from the fibers of the maguey cactus and used them to catch fish, turtles, ducks, and frogs.