A 50-gallon tank is big enough for a community of mid-sized fish, a small group of larger species, a paludarium or a saltwater reef. This guide covers the 50-gallon-class tanks we link to (two acrylic models listed as 50 gallon, plus a 40-gallon combo if you are short on space), the equipment a 50-gallon setup needs, and what you can realistically keep in it.
Planning a 50-gallon goldfish tank? That volume suits about three to four fancy goldfish, using the common rule of 20 gallons for the first fish plus 10 for each additional one. It is too small for common or comet goldfish, which are usually advised 65 to 75 gallons for a pair. The stocking section below has the details.
- SeaClear 50 Gallon Acrylic Combo (36 x 15 x 20 in)
- SeaClear System II Acrylic Aquarium (listed as 50 gallon, 36 x 15 x 16 in)
TABLE OF CONTENTS
All You Need to Know About 50 Gallon Fish Tanks
| PRODUCT | FEATURES | LATEST PRICE |
|---|---|---|
  1. SeaClear 40 Gallon Acrylic Aquarium Combo Set (36 x 15 x 16 in) |
| Check Price |
  2. SeaClear System II Acrylic Aquarium (listed as 50 gallon, 36 x 15 x 16 in) |
| Check Price |
  3. Eheim Jäger Aquarium Thermostat Heater, 300W |
| Check Price |
  4. Penn-Plax Cascade 700 Canister Filter (185 GPH, tanks up to 65 gallons) |
| Check Price |
  5. Aqueon LED Hood, Black, 36 Inch (21108) |
| Check Price |
Before you click through, check these points on the product pages:
- The first row is the SeaClear 40-gallon combo (36 x 15 x 16 inches), a smaller option than the 50-gallon tanks. The black 50-gallon combo (36 x 15 x 20 inches) is the one reviewed below.
- The SeaClear System II is listed as a 50-gallon tank, but its listed 36 x 15 x 16 inch size works out to about 37 gallons of water. Treat it as a roughly 37-gallon tank when you stock it.
- The Penn-Plax Cascade 700 is rated for tanks up to 65 gallons. The “700” is liters per hour, which is about 185 gallons per hour, not 700 GPH.
- The Eheim Jäger heater linked in the table is the 300-watt model, which is more than most 50-gallon tanks need (see the heater section).
A 50-gallon aquarium holds enough water to forgive small mistakes and gives you room for a good-sized community, a school of active fish or a planted layout. It works for community tanks, single-species tanks and paludariums, all covered below.
Rectangles are the standard shape, but you can also find cubes, bow fronts and hexagons. Two “50-gallon” tanks can have very different footprints, so check length and depth, not just the label.
Plan on regular partial water changes and occasional glass and substrate cleaning. A pump or siphon makes draining easier, and our guide on cleaning and maintaining the tank covers the routine. Bottom feeders such as plecos (check the adult size of the species you buy, because some outgrow a 50-gallon) or Corydoras pick up leftover food, but they do not replace water changes.
Prices change often, so use the Check Price buttons for current numbers. Budget for more than the tank itself: a heater, filter, lighting, a stand, substrate, a water test kit and dechlorinator all add to the cost.
50 Gallon Fish Tank Dimensions
A US gallon is 231 cubic inches, so 50 gallons is 11,550 cubic inches of water. A common glass 50-gallon measures about 36″ long, 18″ wide and 19″ high on the outside. The SeaClear acrylic tanks reviewed here have a different footprint: 36 x 15 inches, and they are 20 inches high (50-gallon combo) or 16 inches high (System II and the 40-gallon combo).
Length matters most. A longer tank gives fish more swimming room and more surface area for oxygen exchange, which is why a 4-foot 50-gallon often suits active fish better than a cube.
Weight is the other number to plan for. Water weighs about 8.3 pounds per gallon, so 50 gallons is roughly 415 pounds before you add the tank, substrate and rock.
The Best 50 Gallon Tanks Reviewed
SeaClear 50 Gallon Acrylic Combo Aquarium (36 x 15 x 20 in)
SeaClear 50 Gallon Acrylic Combo, Black
A 50-gallon acrylic tank sold as a combo set with a light fixture.
This is the black 50-gallon SeaClear combo, listed on Amazon at 36 x 15 x 20 inches. It is sold as a combo set with a light fixture, so check the listing for exactly what is included, such as bulbs and hood. Plan to add your own filter and heater, which lets you choose the brands you prefer.
Acrylic is lighter than glass and more impact resistant, which helps when you are moving or setting up a tank this size. The trade-off is that acrylic scratches more easily than glass. Clean it with acrylic-safe pads and never use metal blades or abrasive scrubbers.
Pros:
- Lighter than a glass tank of the same volume.
- Clear acrylic gives an unobstructed view.
- The 15-inch depth makes it easy to reach the back of the tank.
Cons:
- Acrylic scratches more easily than glass.
- You may need to move the light fixture to feed the fish.
- The 36 x 15 inch footprint is narrower than many 50-gallon glass tanks, so match your stand to it.
SeaClear System II Acrylic Aquarium (listed as 50 gallon)
SeaClear System II Acrylic Aquarium, Cobalt Blue
An acrylic tank listed as 50 gallon (36 x 15 x 16 inches, about 37 gallons by volume) with a wet/dry filter compartment built into the back.
This is the SeaClear System II, an acrylic tank with a wet/dry filtration compartment built into the back. The compartment holds biological, mechanical and chemical media, and there is room for your own heater (and a protein skimmer if you convert it to saltwater).
Check the dimensions before you buy. The Amazon listing is titled 50 gallon but gives 36 x 15 x 16 inches, which works out to about 37 gallons of water (8,640 cubic inches), while other retailers list a SeaClear System II 50-gallon at 36 x 15 x 20 inches. Think of the linked tank as a 37-gallon option, and stock it for the actual water volume, not the label. Also confirm whether a hood and lighting are included, since they are not clear from the listing.
Pros:
- Acrylic is lighter than glass and more impact resistant.
- Built-in compartment for filter media.
- Room for a heater behind the main display area.
Cons:
- The linked listing is about 37 gallons by volume, not 50.
- The filter compartment takes up space inside the tank.
- Acrylic scratches more easily than glass.
Tank Equipment
Heater
Eheim Jäger Aquarium Thermostat Heater, 300W
A submersible thermostat heater. The linked listing is the 300-watt model.
A heater keeps the temperature steady, which matters more than the exact number. Most tropical freshwater fish do well in the mid-70s to around 80°F, but check what each species you plan to keep needs and make sure they overlap.
For wattage, a common rule is 3 to 5 watts per gallon. That is 150 to 250 watts for a 50-gallon tank, with the higher end for cool rooms. The 300-watt Eheim linked here suits a cold room or a larger tank.
Goldfish are the exception. Fancy goldfish do best at roughly 50 to 70°F, so a goldfish tank usually does not need a heater at all.
Filter
Penn-Plax Cascade 700 Canister Filter
A canister filter rated for tanks up to 65 gallons. The “700” is liters per hour, about 185 GPH.
Filters remove waste and also create the current in your tank. In a 50-gallon tank you can use a hang-on-back, internal or canister filter, as long as the flow suits your fish.
Look at the rated flow in gallons per hour, and keep in mind that manufacturer ratings assume a lightly stocked tank. A common starting target is a flow of at least 4 times the tank volume per hour (about 200 GPH for 50 gallons). The Cascade 700 is about 185 GPH, so it is at the low end for a heavily stocked tank. Goldfish and other messy fish do better with a filter rated for a larger tank.
Stand
A stand is not optional for a 50-gallon tank. With water, substrate, rock and the tank itself, the total weight is well over 500 pounds, so the stand has to be built for aquariums and rated for that load. A cabinet stand also gives you somewhere to store a filter, test kits and supplies.
Match the stand to the tank’s footprint. A 36 x 15 inch acrylic tank does not sit on a stand made for a 36 x 18 inch glass tank, so check the stand’s top dimensions before you order. The surface under it should be level and the stand should sit evenly on the floor.
Hood
Aqueon LED Deluxe Full Hood, 36 Inch
A 36-inch Aqueon LED hood, listed for glass top aquariums. Hoods are sold by tank length, so check that it fits your tank.
A hood keeps fish from jumping out, cuts evaporation and holds your lighting. Active fish, including many danios, barbs and goldfish, can leap through an open top.
Hoods are sold by length, so check the one you choose against your tank. A 36-inch hood suits a tank about 36 inches long. If you pick a tank with a different footprint, such as a 24 x 24 inch cube, the hood needs to match that tank.
50 Gallon Fish Tank Stocking Suggestions
Gallons are only part of the stocking question. Tank length, adult size, temperament and how much waste a fish produces matter just as much. Always check a species’ adult size and minimum tank before you buy, because juveniles in a store look much smaller than they will be in a year.
Can you keep goldfish in a 50 gallon tank?
Yes, but how many depends on the type. For fancy goldfish, a common guideline is 20 gallons for the first fish and 10 more for each additional one. That puts a 50-gallon tank at a ceiling of about four fancy goldfish, and three gives more margin. A pair of Orandas is comfortable.
Common, comet and shubunkin goldfish grow larger and swim faster. Guidance for two of them is 65 to 75 gallons, so a 50-gallon tank is too small for them in the long term and a pond is a better home.
Goldfish are messy, so use a filter rated for a larger tank, add surface agitation for oxygen, and do regular partial water changes. A wider tank with more surface area suits them better than a tall, narrow one. They prefer cooler water than tropical fish, so don’t mix them with tropical community fish.
What cichlids suit a 50 gallon tank?
Many dwarf cichlids and smaller cichlids, including some African and Malawi species, fit comfortably. Others do not. Peacock cichlids and many Malawi fish do better with more length, and large species are out of the question. A single adult oscar, for example, is usually given 75 gallons at the very least, and Seriously Fish lists a bare minimum of 143 gallons for one (see our guide to the types of oscar fish).
Which gouramis work in a 50 gallon tank?
Gouramis are generally calmer than most cichlids, though temperament varies by species and sometimes by individual. A 50-gallon tank gives you room for a small group of a peaceful species such as the pearl gourami or snakeskin gourami. Paradise fish are a different option. Check each species before mixing, and keep one male per species unless the tank is heavily planted.
Can you keep saltwater fish in a 50 gallon tank?
Yes, with limits. A 50-gallon reef tank suits small marine fish such as clownfish and gobies, which are commonly kept at this size. It does not suit a blue tang, which is usually given 125 gallons at a minimum and 180 or more as it grows. A mandarinfish is possible only in a mature tank, usually at least six months old, with a large population of copepods to feed it, because it eats almost exclusively live copepods.
Now that you know your stocking choices, here are the setup options.
Community Tank
One of the most popular choices for a bigger tank is a community aquarium. It combines several peaceful species, with some plants, that share the same water needs.
First decide on freshwater or saltwater, because that also decides the plants, lighting and equipment. Then pick fish with matching temperature and water chemistry and with different swimming levels, so some live near the top, middle and bottom. Don’t mix goldfish with tropical fish.
Species Only Tank
A species-only tank holds one type of fish, which suits larger fish or a group of schooling fish you want to see behaving naturally. A small group of angelfish is a common choice. Oscars and other Astronotus are not, because they outgrow a 50-gallon (see the oscar fish guide).
This setup also works for fish that don’t get along with other species. A betta fish should live without other males, and a school of cherry barbs in a planted tank is a peaceful alternative. Whatever you choose, check the space each species needs.
Paludarium Tank
A paludarium is part water and part land, with aquatic and terrestrial plants and animals. It can house freshwater or brackish fish, plus amphibians, snails and small crustaceans. Reptiles and turtles are possible too, but they have their own heat, lighting and space needs, and many aquatic turtles will eat fish.
The main advantage of the setup is variety. Plan the water and land areas around the animals you keep, and keep the stocking modest, since each animal needs its own space and conditions.
How To Set Up A 50 Gallon Fish Tank
Setting up a tank follows the same basic steps whatever you keep. The main differences are saltwater needs and the filter and lighting you choose.
- Decide on freshwater or saltwater, and pick fish first, so you can match the equipment to their needs.
- Rinse the empty tank with plain water. Don’t use soap or detergent.
- Choose the spot carefully. It should be level, away from direct sunlight and heat sources, near an outlet, and on a stand built for the weight.
- Rinse the substrate and spread it evenly across the bottom.
- Install the equipment: a powerful internal or external filter, a heater if your fish need one, and lighting. Add rock, wood and plants.
- Fill the tank, treat tap water with a dechlorinator and start the filter. For saltwater, mix and test the salt first.
- Cycle the tank before adding fish. Beneficial bacteria need to build up to turn ammonia into nitrite and then nitrate, which typically takes several weeks. Use a test kit, and add fish once ammonia and nitrite read zero.
- Add fish gradually, a few at a time, rather than all at once.
- Acclimate each fish. Float the sealed bag for about 15 minutes to match the temperature, then add small amounts of tank water to the bag every few minutes before releasing the fish.
Summary
A 50-gallon tank is a flexible size for beginners and experienced keepers. Maintenance takes more time than on a 5 gallon tank, mostly because of the larger water changes. It supports community, species-only and mixed land-and-water setups, and it is large enough for a stable, forgiving system.
Common mistakes to avoid:
- Stocking by the size fish are in the store instead of their adult size.
- Adding fish before the tank has cycled.
- Putting goldfish in with tropical fish, or common goldfish in a tank under 65 gallons.
- Using a stand that is not rated for roughly 500 pounds or does not match the tank footprint.
- Buying a hood or heater without checking its size and wattage against the tank.
Of the tanks above, SeaClear’s Combo Aquarium is a lightweight acrylic option for most freshwater setups, as long as you add your own filter and heater.
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