The Swordtail is a freshwater livebearer that is extremely popular in the fish keeping hobby. The average Swordtail reaches 5 when fully grown and can be housed in 10 gallon aquariums. However, youre more than likely going to have more than one Swordtail, and in that case, you will need a larger aquarium. When adding tankmates with your Swordtail, you want to choose similar in size peaceful community fish.