Petco stocks a reliable range of aquarium heaters from Aqueon, Fluval, and Tetra, covering most freshwater and marine tank sizes from 5 to 75 gallons. If you need a heater today, Petco is a solid option for standard submersible glass heaters in the 50 to 300 watt range. For larger tanks, specialty heaters, or titanium models better suited to marine setups, online retailers and Amazon typically offer better selection and pricing.
This article breaks down what you'll actually find at Petco, compares the major brands, and explains what to look for in an aquarium heater regardless of where you buy it.
What Heaters Does Petco Actually Carry?
Most Petco stores stock heaters from three brands: Aqueon, Tetra, and Fluval. The exact inventory varies by store, but here's what you'll typically find:
Aqueon Heaters at Petco
Aqueon is one of the most consistently stocked brands at Petco. Their submersible Pro heater line comes in 50W, 100W, 150W, 200W, and 300W versions. These are glass submersible heaters with an external adjustable dial and a built-in indicator light that shows when the heater is actively heating.
The Aqueon Pro heaters are well-regarded for accuracy, typically maintaining temperature within 1 to 2 degrees of the setpoint. The 100W model is priced around $25 to $35 in-store. These work well for freshwater tanks up to about 50 gallons, but I'd use them with caution in saltwater tanks where glass breakage from thermal shock or livestock contact is a real risk.
Tetra Heaters at Petco
Tetra submersible heaters are often the budget choice at Petco. The HT30 (30W for tanks up to 10 gallons) and HT50 (50W for tanks up to 30 gallons) are common. These are pre-set to 78 degrees F and can't be adjusted, which makes them very simple but inflexible. Fine for a betta tank or a tropical community tank where 78 degrees is your target temperature.
Tetra also makes a more advanced line, the HT Submersible Heater, which is adjustable. These are competent but have mixed reviews on long-term reliability.
Fluval Heaters at Petco
Petco often carries the Fluval E series, one of the more sophisticated options available at pet stores. The Fluval E100 (100W) and E200 (200W) have LCD displays that show both actual water temperature and set temperature simultaneously, which is genuinely useful for monitoring at a glance. They also have a temperature alarm and a safety shut-off.
The Fluval E200 retails around $50 to $65 at Petco, which is on the higher end, but the dual-display feature and accuracy justify it for hobbyists who care about stability.
What Petco Doesn't Carry (and Why It Matters)
For saltwater tanks, reef tanks, or larger setups, Petco's in-store selection falls short. You typically won't find:
Titanium heaters: Far more durable than glass in marine environments. Brands like Finnex (TH-300S) and Aquatop are available online but rarely in Petco stores.
In-line heaters: These mount on the output line of your canister filter, so the heater never enters the display tank. Popular options like the Hydor ETH 200 or Fluval M200 are primarily online products.
Large wattage units: Petco occasionally stocks 300W heaters but rarely anything larger. Tanks over 75 gallons typically need 400 to 600 watts of heating, which means sourcing online.
Controllers and probes: Precision temperature controllers like the Inkbird ITC-306A, which turns a dumb heater into a smart one with more precise control, are not found at Petco.
For reef heaters specifically, check the Best Reef Tank Heater guide to see which models work best in saltwater environments, and the Best Aquarium Equipment roundup for broader comparisons.
How to Size an Aquarium Heater
The standard rule is 3 to 5 watts per gallon, but that doesn't account for ambient room temperature. If your house stays at 68 to 70 degrees F, you need more wattage than if it stays at 72 to 75 degrees.
Practical sizing: - 5 to 10 gallon tank, average room temp: 25 to 50W (Tetra HT10 or Aqueon 50W) - 10 to 30 gallon tank: 50 to 150W - 30 to 55 gallon tank: 150 to 200W - 55 to 75 gallon tank: 200 to 300W - 75 to 125 gallon tank: 300 to 500W (usually two heaters) - Over 125 gallons: Two heaters totaling at least 5W per gallon
For tanks over 55 gallons, I always recommend two heaters. Running two heaters set to the same temperature means if one fails stuck-on, the other heater doesn't need to compensate, so the temperature only climbs slightly before you notice. If one fails stuck-off, the other keeps the tank warm enough until you replace it.
Adjustable vs. Pre-Set Heaters
Pre-set heaters (like the Tetra HT series) lock in a fixed temperature, typically 78 degrees F. They're simpler, have fewer failure points, and are fine if your target temperature matches the preset.
Adjustable heaters give you control over temperature setpoint, which is necessary for tanks requiring specific conditions: goldfish prefer 65 to 72 degrees F, discus need 84 to 88 degrees F, and some marines are better at 76 degrees than 80. Any adjustable heater sold at Petco will have a dial from roughly 68 to 88 degrees F.
One thing to verify with any adjustable heater is whether the dial markings are accurate. I've tested Aqueon and Fluval heaters and found them to be within 1 to 2 degrees of the dial setting, which is acceptable. Cheaper no-name heaters can be off by 5 degrees or more.
Using a Separate Temperature Controller
Even good heaters benefit from a separate temperature controller. The concept is simple: you plug the heater into the controller, set the controller to your target temperature, and the controller uses its own probe to cycle the heater on and off independently of the heater's own thermostat.
The Inkbird ITC-306A (~$35 online) is the most popular affordable option. It has two outlets (cooling and heating), a clear display, and audible alarms. Using one with any heater from Petco effectively turns a $30 heater into a more reliable and accurate system than any individual heater's built-in thermostat.
Heater Placement Tips
Placement significantly affects how evenly your tank heats. The best position for most heaters is horizontal or at a 45-degree angle near a powerhead or filter output where flow carries warm water through the tank. Vertical placement near the intake of a strong return pump also works well.
Avoid placing heaters: - In the dead corner of a tank with no flow - Directly on the substrate, where sediment can cover the temperature sensor - Close to the water surface, where they can run partially exposed if the water level drops
In saltwater tanks and reef tanks, heaters in the sump (rather than the display) are preferred. This keeps glass heaters out of reach of corals, snails, and hermit crabs, all of which can break or move a heater against the glass.
FAQ
Are Petco heaters good quality? Aqueon and Fluval heaters available at Petco are reliable options for most freshwater setups. They're not cutting-edge but they're consistent and widely used. For marine tanks, titanium heaters purchased online are a better long-term investment.
Can I use an aquarium heater from Petco in a saltwater tank? Yes, but glass heaters carry more risk in saltwater tanks because the minerals and livestock interactions increase the chance of cracking. Titanium or shatterproof heaters are safer for marine use.
How do I know if my heater is accurate? Use a separate thermometer, not the heater's built-in indicator. A $10 digital thermometer with a probe gives you actual water temperature to compare against your heater's setpoint.
How long do aquarium heaters last? Most quality heaters last 2 to 5 years with normal use. Replace preemptively every 3 years on tanks with expensive livestock rather than waiting for failure. Heater failure in either direction, stuck-on or stuck-off, can be fatal to fish.
Conclusion
Petco is a convenient source for Aqueon and Fluval heaters in the 50 to 300 watt range, which covers most freshwater tanks. For marine tanks, large setups over 75 gallons, or if you want titanium heaters and independent controllers for better reliability, shop online where selection and pricing are better. Always pair a heater with a separate digital thermometer, consider using two heaters on larger tanks, and replace heaters proactively before they fail.