One of the most crucial aspects of aquarium care is lighting. The strength and quality of the light directly affect the plants and animals in the tank.
In winter, keep the aquarium close to light sources, ideally near windows facing south or east. In summer, position it further from direct sunlight, near west- or north-facing windows. If you can’t move the tank and must keep it by a sunlit window in summer, cover it to prevent overheating. Otherwise the water can become too warm and microscopic aquatic plants can turn the tank into a murky swamp. Use houseplants to filter the sunlight so only diffused rays reach the aquarium. Make sure the bottom of the aquarium is not lower than the windowsill.
In summer, replenish the oxygen in the aquarium daily; in winter, every other day is sufficient.
Fill a cup with aquarium water and pour it from as high as you can so it splashes onto a hard surface (like a rock, a board, or a floating cork). The smaller the droplets, the more air they capture.
Place or suspend a container above the aquarium so water drips into it. Aerate the water using a glass, rubber, or reed tube.
Water temperature is vital for fish health. Most local fish thrive around 14–17°C (57–63°F), while trout, perch, and burbot prefer cooler water around 10–14°C (50–57°F). Tropical fish need warmer water, ideally between 18–24°C (64–75°F).
Heat the water with submerged electric bulbs; use colored bulbs or shade them with plants. Avoid sudden temperature changes—most fish can’t tolerate them.
Don’t change all the water at once. Partially refresh the water about once a week in summer and twice a month in winter. Use a rubber tube: submerge one end in the aquarium and put the other end in a container lower than the tank to siphon out about a third of the water, then replace it with fresh water.
About a day after a water change, clean the aquarium glass inside and out, since a green film of microscopic algae tends to form. Use a stiff toothbrush for this task.
In summer, skip cleaning the glass facing the window or clean it only in spots—sunlight filtered through a thin layer of algae can actually benefit the fish. Don’t use sand to clean the glass. For external cleaning, use newspaper or wrapping paper.
Clean the bottom daily from debris, leftover food, and fallen leaves. The easiest way is with a rubber tube. Hold the top end a short distance above the water in your right hand while lowering the bottom end into a container placed lower than the aquarium. Suck air through the bottom end until water starts flowing. Move the top end around the bottom; the dirt will be drawn into the tube with the water.
To retrieve leftover food or an object from the bottom, use a glass tube. Cover the top opening with your finger, lower the bottom end to the item, then release your finger from the top. The water will carry the item into the tube. Cover the top opening again, remove the tube, and discard the water.
