They make 5 gal,5.5 gal,6 gal tanks,so you would have to go by the size in inches of the tank to find it`s size.I would say to stay with the 5 guppies.You can put more in but you woulf need a good filter that is over rated and lots of water changes and testing your tank a couple of times a week.If you have males and females then at some point you will have fry.Then you will need more room and more tanks.
Did you do your water change today
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