What Size Tank Do Platies Need?
Adult standard length 2.0 inches. The published tank is 24 × 12 × 12 inches, about 14 US gallons.
Full breakdown: how many fish per gallon. Full breakdown: how many fish in a 20 gallon tank.
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The figures
| Figure | Value | Source |
|---|---|---|
| Adult standard length | 2.0 in | Seriously Fish |
| Minimum aquarium | 24 × 12 × 12 in | Seriously Fish |
| Approximate volume | 14 US gallons | Seriously Fish |
| Group / social | No group count is given on the profile figures used here | Seriously Fish |
| Filter rating | 215-270 liters per hour | Seriously Fish |
| Filter rating in gallons per hour | 56.80-71.33 gph | Calculated from the published liters per hour ÷ 3.785 (Seriously Fish; 1 US gallon = 3.785 liters) |
| Temperature | 68-79°F | Seriously Fish |
| Heater on the profile | 50 watts, assuming a room around 68°F | Seriously Fish |
| Aqueon band that contains about 14 gallons | 50 watts for 5-20 gallons | Aqueon |
Full breakdown: what size filter for a 20 gallon tank.
How to size it
Seriously Fish prints the platy tank as a box, not only a floor: 24 × 12 × 12 inches, about 14 US gallons. The floor matches the neon tetra, cherry barb, and harlequin rasbora minimums. The 12 inch height is stated for the platy, as it is for the guppy and the molly. Adult standard length is 2.0 inches. No group size is printed in the figures used here, so none is added.
The temperature is the part that is not shared. Platies are listed at 68-79°F with a 50 watt heater, assuming a room around 68°F. Neon tetras are listed at 70-77°F, also on 50 watts. Cherry barbs run warmer on the heater line (50-75 watts) even though the volume is the same. Aqueon still sees one tank size: about 14 gallons is inside 5-20, so 50 watts is the listed band, and it is just short of 15, so the 100 watt band does not apply.
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Accessory: a 50 watt heater, the wattage on the platy profile and the Aqueon band for about 14 gallons. Shop a 50 watt aquarium heater on Amazon
Related pages
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FAQ
What size tank do platies need?
Seriously Fish lists 24 × 12 × 12 inches, about 14 US gallons, for Xiphophorus maculatus. Adult standard length is 2.0 inches. The profile figures used here do not include a group count.
What filter rating is listed for platies?
Seriously Fish lists 215-270 liters per hour. Dividing by 3.785 gives 56.80-71.33 gallons per hour.
What heater wattage matches a platy tank of about 14 gallons?
Seriously Fish lists 68-79°F and a 50 watt heater, assuming a room around 68°F. Aqueon lists 50 watts for 5-20 gallons, which includes about 14 gallons. The 100 watt band starts at 15 gallons.
Sources
- Seriously Fish, Xiphophorus maculatus. https://www.seriouslyfish.com/species/xiphophorus-maculatus/. Accessed Oct 2, 2026.
- Aqueon, Heater Wattage Guidelines. https://www.aqueon.com/-/media/project/oneweb/aqueon/files/us/educational/aq_heater_wattage_chart.pdf. Accessed Oct 2, 2026.