Question: 5 gallon tank how many guppies?
Answer: As long as your guppies have enough room and you treat them right, they should live to old age no problem. Just remember that you should not keep more than 1 inch, or 1.5 inches at most, of fish per gallon of water. Therefore, in a 5 gallon tank, keeping more than 3 or 4 guppies is not recommended.