Question: how many litres of water per guppy?
Answer: A general guideline is 1 guppy per 4 litres of water. For purposes of the appreciation of guppies, a tank of around 45 litres (10 gallons) will be suitable for a sizable number of guppies to coexist in the tank. For breeding purposes, a smaller tank could be used due to the smaller number and number of fishes.