There is no exact answer to the question of how many Sparkling Gourami should be kept in a gallon of water. The general rule of thumb is that you should have one fish per 10-20 gallons of water, but this may vary depending on the size and temperament of your particular species. It's important to research each type of fish before making any decisions about stocking levels, as some species require more space than others and overcrowding can lead to stress or illness. Furthermore, it's also essential to consider factors such as filtration capacity and temperature when deciding how much stock a tank can handle - certain types will need warmer temperatures or higher oxygen levels than others, so make sure these points are taken into account when planning your aquarium setup.