What Size Tank Does a Bristlenose Pleco Need?
Adult standard length 5 inches. A 31 × 12 inch base, about 19 US gallons, is enough for a couple; a group needs larger.
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 | 5 in | Seriously Fish |
| Minimum aquarium base | 31 × 12 in | Seriously Fish |
| Approximate volume | 19 US gallons | Seriously Fish |
| Group / social | Sufficient for a couple of specimens; larger for a group | Seriously Fish |
| Filter rating | 290-360 liters per hour | Seriously Fish |
| Filter rating in gallons per hour | 76.62-95.11 gph | Calculated from the published liters per hour ÷ 3.785 (Seriously Fish; 1 US gallon = 3.785 liters) |
| Temperature | 77-86°F | Seriously Fish |
| Heater on the profile | 125-150 watts, assuming a room around 68°F | Seriously Fish |
| Aqueon bands that contain about 19 gallons | 50 watts for 5-20 gallons, and 100 watts for 15-40 gallons | Aqueon |
Full breakdown: what size filter for a 20 gallon tank.
How to size it
Share the cory footprint, not the cory heater. Seriously Fish uses 31 × 12 inches and about 19 US gallons, and it says that is sufficient for a couple of specimens, with a larger tank for a group. The 20 gallon long search is the shopping match for a 31 inch base. Adult standard length is 5 inches, longer than the bronze cory's 3.0 inches, on the same floor.
Four times about 19 gallons is 76, and five times is 95. The converted rating meets that turnover. Nothing on the profile marks this flow as gentle.
The temperature is hot for a 19-gallon tank: 77-86°F, with 125-150 watts, assuming a room around 68°F. Aqueon still classifies about 19 gallons as a 50 watt tank (5-20) and a 100 watt tank (15-40). Both of those ratings are below 125. The 150 watt Aqueon band does not start until 30 gallons, so a 150 watt line on the species profile is not the same claim as Aqueon's 150 watt band. Report the gap; do not invent a wattage in between.
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Accessory: a 125 watt heater, the bottom of the profile's 125-150 watt span. Aqueon's bands for about 19 gallons are 50 and 100 watts, as the table shows. Shop a 125 watt aquarium heater on Amazon
Related pages
- Stocking calculator
- What size tank a bronze cory needs
- What size tank a German blue ram needs
- What size heater a 29 gallon tank needs
FAQ
What size tank does a bristlenose pleco need?
Seriously Fish lists a minimum base of 31 × 12 inches, about 19 US gallons, for Ancistrus sp., and calls that sufficient for a couple of specimens. A group needs a larger tank. Adult standard length is 5 inches.
What filter rating is listed for a bristlenose pleco?
Seriously Fish lists 290-360 liters per hour for Ancistrus sp. on the 31 × 12 inch base. Dividing by 3.785 gives 76.62-95.11 gallons per hour. Four times about 19 gallons is 76 gallons per hour, and five times is 95.
Why is the bristlenose heater above the Aqueon bands for 19 gallons?
Seriously Fish lists 77-86°F and a 125-150 watt heater, assuming a room around 68°F. Aqueon lists 50 watts for 5-20 gallons and 100 watts for 15-40 gallons. About 19 gallons is inside those two bands, and both are below 125 watts.
Sources
- Seriously Fish, Ancistrus sp.. https://www.seriouslyfish.com/species/ancistrus-sp/. 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.