The cheapest aquariums come from big-box retailers and online marketplaces, but price alone won't tell you if a tank will last

Walmart, Target, and Amazon stock aquariums in the $20 to $60 range for small tanks, and these are genuinely cheaper than specialty shops. Petco and PetSmart run frequent sales that undercut their regular prices by 20 to 40 percent, especially on 10-gallon and 20-gallon models. Facebook Marketplace and Craigslist often have used tanks for $10 to $30 — sometimes complete with filters and gravel — because people abandon the hobby and need the space.

The catch is that cheap tanks often have thin glass, poor seals, or frames that warp. A $25 tank that leaks in month three costs more in the long run than a $50 tank that holds water for a decade. The real savings come from knowing which brands hold up and which retailers actually discount without cutting corners.

Key Takeaways

  • Walmart and Target sell small aquariums for $20 to $40, and Petco and PetSmart discount their stock by 20 to 40 percent during sales cycles.
  • Used tanks on Facebook Marketplace and Craigslist run $10 to $30 and often include filters and substrate, but inspect the glass and seals before buying.
  • Aqueon, Tetra, and Marineland tanks are more reliable at budget prices than no-name brands, even if they cost $10 more upfront.
  • Avoid tanks smaller than 5 gallons — they cost less but are harder to maintain and stress fish more than larger models.
  • Check return policies before buying online; a leaking tank is worthless, and some retailers won't accept returns on aquariums.

Where to find the lowest prices on new tanks

Walmart and Target carry 10-gallon and 20-gallon aquariums year-round at $25 to $50. These are usually Aqueon or Tetra brand, which are reliable enough for the price. Stock changes by location and season, so call ahead or check the website to see what's in your store.

Petco and PetSmart run sales every 4 to 8 weeks that drop prices 20 to 40 percent off the regular tag. Sign up for their email lists or check their apps — the sales rotate between different tank sizes, so a 20-gallon might be on sale one month and a 40-gallon the next. These stores also price-match Amazon and Walmart if you bring proof, which can save you another 10 percent.

Amazon sells aquariums from $15 for a 5-gallon betta tank to $80 for a 40-gallon breeder box. Shipping is often free on orders over $25, but check the weight — a 40-gallon tank can cost $15 to $25 to ship if it doesn't may have access to for free delivery. Read the reviews carefully; cheap tanks on Amazon often have complaints about cracks or cloudy glass.

Used tanks: what to inspect and where to look

Facebook Marketplace and Craigslist list used aquariums constantly because people move, lose interest, or upgrade. A 20-gallon tank that cost $60 new often sells for $20 to $30 used, and many include the filter, heater, and substrate. The risk is that you cannot return it, so you have to inspect it in person before handing over money.

Before you buy, fill the tank with water in the seller's driveway or garage and let it sit for 10 minutes. Look for slow leaks around the seams and corners — even a drip means the silicone seal is failing and the tank will fail at home. Check the glass for cracks, cloudiness, or scratches deep enough to catch your fingernail. If the frame is plastic, flex it gently; if it bends or creaks, the tank may not hold its shape when full.

Ask the seller how long they used it and why they stopped. A tank used for two years and then stored is usually fine. A tank that was sitting in a garage for five years may have degraded silicone even if it looks clean. If the seller won't let you test it, walk away — a good deal is not worth a flooded living room.

Brands that hold up at budget prices

Aqueon makes 10-gallon and 20-gallon tanks that Walmart and Target stock. The glass is thicker than no-name brands, the seals hold, and they come with a basic hood and light. A 20-gallon Aqueon costs $35 to $50 new and will last 5 to 10 years with normal use.

Tetra tanks are sold at Petco, PetSmart, and Amazon. They are slightly more expensive than Aqueon but have better lighting and filtration options. A Tetra 20-gallon runs $45 to $65 and includes a filter rated for the tank size, which saves you $20 to $30 on a separate purchase.

Marineland makes smaller tanks (5 to 10 gallons) that are durable and compact. They cost $20 to $40 and are good for betta fish or a few small community fish. The glass is reliable, though the included filter is basic.

Avoid tanks with no brand name or only a retailer's house brand (like Aqua Culture at Walmart). These are the cheapest upfront but often leak within a year. The money you save on the tank gets spent replacing it.

Tank size and what it costs you

A 5-gallon tank costs $15 to $25, but it is harder to maintain than a 10-gallon. Water temperature swings faster, ammonia builds up quicker, and fish get stressed. You end up buying more water treatments and doing water changes more often. A 10-gallon costs $20 to $35 and is much easier to keep stable.

A 20-gallon is $30 to $60 and gives you room for more fish or plants without the maintenance burden of a 5-gallon. If you are new to aquariums, a 20-gallon is often the cheapest option in the long run because it requires less intervention and fewer replacement parts.

A 40-gallon breeder tank or larger costs $60 to $150 but is only cheaper if you plan to keep it for years. If you are testing the hobby, start with a 10 or 20-gallon and upgrade later.

What to check before buying online

Read the return policy. Some retailers, including Amazon, will not accept returns on aquariums if they have been filled with water. Others allow returns within 30 days as long as the tank is dry and undamaged. If a tank arrives cracked or leaks on the first fill, you need to know you can send it back.

Check the shipping cost and weight. A 40-gallon tank weighs 50 to 60 pounds and may cost $20 to $40 to ship, which erases the savings from a sale price. A 20-gallon weighs 25 to 30 pounds and usually qualifies for free shipping on orders over $25.

Look at the photos and read the reviews. If multiple reviewers mention cracks, cloudiness, or leaks, that tank has a real problem — it is not a one-off. If the photos show the tank sealed in a box with air pillows, that is a good sign. If the photos show it loose in a larger box, it may arrive damaged.

Timing your purchase for the best prices

Petco and PetSmart run sales in cycles. Watch their websites or apps for 4 to 8 weeks and you will see the pattern — one month a 10-gallon is 30 percent off, the next month a 20-gallon is 40 percent off. If you are not in a hurry, wait for your tank size to go on sale rather than buying at full price.

Walmart and Target do not discount as heavily, but they run seasonal promotions around back-to-school (August) and after the holidays (January). These are when people set up new tanks, so stock is highest and prices are competitive.

Used tanks are cheapest in spring and early summer when people move and clean out their homes. Fall and winter see fewer listings because people are less likely to sell in cold months.

Frequently Asked Questions

Is a $20 aquarium worth buying?

A $20 tank from Walmart or Target is worth buying if it is an Aqueon or Tetra brand and at least 10 gallons. A $20 no-name brand or a 5-gallon tank will likely leak or fail within a year, which makes it more expensive than a $40 tank that lasts five years.

Can I use a used aquarium without cleaning it first?

Rinse the inside with hot water and wipe it dry, but do not use soap or chemicals — they leave residue that harms fish. If the tank smells like algae or mold, soak it in a 10 percent bleach solution for an hour, rinse thoroughly with hot water five times, and let it air dry for a day before filling.

What should I do if a tank leaks after I buy it?

If it leaks within the return window, contact the retailer with photos and your receipt. If you bought it used, you have no recourse — that is the risk of buying secondhand. If it leaks after the return period, you can try resealing it with aquarium silicone, which costs $5 to $10 and takes a day to cure.

Are tall tanks cheaper than long tanks?

Tall tanks (20-gallon high) and long tanks (20-gallon long) cost about the same, but long tanks are easier to maintain and better for most fish. Tall tanks are harder to reach the bottom and create dead zones where waste builds up. Buy the long version if both are the same price.

Should I buy a tank kit with filter and heater included?

Kits save money upfront — a 20-gallon kit with filter and heater costs $60 to $80, while buying separately costs $80 to $120. The filter and heater in kits are basic but functional. If you plan to upgrade later, a kit is a good starting point. If you want better equipment from the start, buy the tank alone and choose your own filter.