The filter is the life-support system. It removes physical debris and provides a home for beneficial bacteria that neutralize toxic fish waste.
For beginners, a 20-gallon tank is often recommended. Larger volumes are actually easier to maintain because water chemistry stays more stable. Freshwater Aquariums Basic Aquarium Setup and M...
Most tropical fish require a steady temperature between 75°F and 80°F. The filter is the life-support system