A lowboy aquarium is a tank with a wide, shallow footprint and a low height, typically 12-18 inches tall with a disproportionately wide length and depth. In the aquarium hobby, lowboy tanks are used most often for display corals and anemones (because of even light distribution at shallow depth), for bottom-dwelling fish species that use horizontal space rather than height, and for bare-bottom frag tanks in reef systems. They're not commonly sold as off-the-shelf products, which means most lowboy setups are either custom-built or sourced from specialty aquarium manufacturers.
If you're looking at lowboy tanks, you're probably setting up a coral frag system, a killifish or shell-dweller tank, or a shallow reef display. This guide covers the different uses, tank dimensions to expect, how to set one up, and what to consider for filtration and lighting.
What Defines a Lowboy Tank
There's no universal standard for "lowboy" dimensions, but in practice it means a tank where the height is much less than the length. Common examples:
- 24 x 24 x 12 inches (about 30 gallons)
- 36 x 24 x 12 inches (about 45 gallons)
- 48 x 24 x 12 inches (about 60 gallons)
- 72 x 24 x 12 inches (about 90 gallons)
Compare these to a standard 75-gallon tank, which is 48 x 18 x 21 inches. The lowboy version at 48 x 24 x 12 holds similar volume but at half the height and wider depth.
Some hobbyists use the term "long low" to describe these tanks in the freshwater planted tank context, particularly popular in Japan where shallow, wide planted tanks (influenced by the Nature Aquarium style of Takashi Amano) have been popular since the 1990s.
The Main Uses for Lowboy Tanks
Coral Frag Systems
This is the most common use for lowboy tanks in the reef hobby. Coral frags (small fragments propagated from parent colonies) are placed on frag plugs or tiles and need high, even light intensity to grow. The shallower the water, the less light intensity is lost to depth.
A typical frag tank is a bare-bottom lowboy (no substrate, for easy cleaning) with strong lighting, high flow, and either its own filtration or connection to a main system via a manifold. Dimensions like 48 x 24 x 12 or 72 x 24 x 12 are common for serious frag operations.
The wide, shallow format means you can fit many more frag plugs at the surface where light is strongest, compared to a deep tank where frags on the bottom receive a fraction of the surface intensity.
Anemone Tanks
Anemones prefer shallow, high-flow environments with intense light. A lowboy with 12 inches of water depth puts an anemone much closer to the light source than a standard 24-inch-deep display tank. Clownfish hosting anemones do particularly well in lowboy setups because the entire tank is essentially "shallow" water where the anemone can choose placement.
Freshwater Biotopes
In freshwater, lowboys work well for recreating shallow water biotopes: shallow streams, rice paddies, and tidal zones. Species like killifish, rice fish (Oryzias spp.), and certain small rasboras and danios that live in shallow water in nature display more natural behavior in a low tank than in a standard-depth aquarium.
Aquatic plants in a lowboy also grow differently: stem plants reach the surface faster and begin emersed growth above the water, which can be cultivated as part of a paludarium-style setup.
Shell-Dwelling Cichlids
Tanganyikan shell-dwelling cichlids (Lamprologus ocellatus, Neolamprologus brevis) are tiny fish that live on the sandy substrate of Lake Tanganyika in shells. They use almost no vertical space. A lowboy tank can house multiple shell-dweller colonies with enough horizontal territory for each pair, whereas a tall standard tank wastes all the height that these fish simply don't use.
Filtration Considerations for Lowboy Tanks
Filtration for a lowboy needs to be calculated based on volume but also adapted to the shallow water column.
High Flow for Reef Lowboys
Reef lowboys need strong water movement to prevent detritus from accumulating and to provide the high-oxygen environment corals prefer. Flow rates of 30-50 times tank volume per hour are typical for frag tanks. For a 45-gallon lowboy, that means 1,350-2,250 GPH of total flow.
Powerheads like the Sicce Voyager or Tunze Turbelle Stream provide high flow with a relatively compact footprint. Position them at opposite ends of the tank for cross-flow that prevents stagnant corners.
Sump vs. Hang-On-Back Filtration
For a standalone lowboy (not connected to a main system), a small sump underneath the stand is the cleanest option. The sump holds the return pump, a small protein skimmer, and any media reactors out of the display area. A sump also provides additional water volume, which helps stabilize parameters in a shallow tank.
Hang-on-back filters work for freshwater lowboys but look bulky on a low tank. They also create a return flow pattern that can disturb the substrate unevenly. A canister filter with a spray bar return spreads the flow more evenly and keeps the equipment out of sight.
Undergravel Considerations
Lowboy tanks do not work well with undergravel filters because the shallow depth means the filter plates take up a proportionally large fraction of the tank height. Skip undergravel filtration for lowboys.
For top-rated filtration and equipment recommendations, check out the Best Aquarium Equipment guide, or the Top Aquarium Equipment roundup for curated picks organized by category.
Lighting for Lowboy Tanks
This is where lowboys shine, literally. With only 12 inches of water depth, you can achieve very high PAR (photosynthetically active radiation) at the substrate with lower-powered fixtures than a standard deep tank would require.
For Reef Lowboys
A single AI Prime HD or Kessil A80 Tuna Blue can cover a 24 x 24 inch section of a lowboy with adequate reef intensity. For a 48 x 24 inch lowboy, two AI Prime HDs or one Kessil A360X provides strong, even coverage. Because the corals are only 12 inches below the light, you run the fixture at lower intensity than you would over a 24-inch-deep display, which extends LED driver life.
PAR at the bottom of a 12-inch lowboy under a single AI Prime HD at moderate output is typically 150-300 depending on mounting height, which is well within the acceptable range for most SPS and LPS corals.
For Planted Freshwater Lowboys
The same lighting logic applies: high PAR at depth is easier to achieve in 12 inches of water than 18 inches. A Finnex Planted+ 24/7 over a 12-inch deep lowboy produces enough light for demanding carpeting plants without the heat and energy cost of high-powered fixtures.
CO2 injection for a planted lowboy can use a smaller setup than a standard tank of similar volume because the shallow depth means CO2 distributes to the substrate more easily.
Substrate and Aquascaping in Lowboy Tanks
The wide, shallow footprint of a lowboy changes how aquascaping works.
With only 12 inches of height, there's limited vertical dimension to work with. Aquascape design in lowboys focuses on horizontal composition: foreground, midground, and background still exist but are more compressed vertically. Use hardscape (rocks, driftwood, dragon stone) with moderate height that doesn't reach too close to the waterline.
For reef lowboys used as frag tanks, bare bottom is simplest for maintenance. Frag plugs rest directly on the glass or on frag racks that hold them at adjustable heights.
For freshwater lowboys, a 1.5-2 inch substrate layer is sufficient. Deeper substrate beds in a 12-inch tank eat up vertical space that the fish need.
Buying a Lowboy Tank
Mass-market aquarium manufacturers rarely offer lowboy dimensions as standard products. The options for sourcing:
Custom glass or acrylic shops: A local glass shop that does aquarium work can build any dimensions you specify. A custom 48 x 24 x 12 glass tank typically runs $200-500 depending on glass thickness and location.
Specialty aquarium retailers: Companies like Crystal Aquatics, JBJ, and some regional specialty stores offer non-standard dimensions including lowboys and custom shallow tanks.
Used market: Search for "frag tank," "coral tank," and "shallow aquarium" in addition to "lowboy" on Craigslist and Facebook Marketplace. Many reef hobbyists sell frag tanks when they upgrade or leave the hobby.
Rubbermaid-style tanks: For functional frag systems where aesthetics are secondary, large Rubbermaid stock tanks and storage totes are used routinely. A 100-gallon Rubbermaid Stock Tank has the shallow, wide profile of a lowboy and costs $80-120 from farm supply stores. They're not pretty but hold water, are easy to drill for plumbing, and are extremely durable.
FAQ
What's the minimum depth for a lowboy fish tank? For fish, 10 inches is about the practical minimum. Below that, fish are crowded vertically and can't swim naturally. For frag or anemone tanks without fish (or with very small fish), as shallow as 8 inches works. Most practical lowboys run 12-18 inches.
Can I use a standard aquarium hood on a lowboy? Probably not, because commercial hoods are designed for standard tank widths and heights. For lowboys, open-top configurations with clip-on lights or pendant lighting are more practical. If you need a cover to prevent jumping fish, custom-cut acrylic panels or egg crate light diffuser grating work well as DIY covers.
Are lowboys harder to maintain than standard tanks? Evaporation is higher proportionally because more water surface is exposed. Top-off with an ATO (automatic top-off) unit if your lowboy is part of a reef system. Access is easier than a deep tank because you don't have to reach as far down. Algae scraping is simpler for the same reason.
What fish are best suited for lowboy tanks? Bottom-oriented fish that don't use vertical space: corydoras catfish, loaches, killifish, rice fish, gobies, mandarin dragonets (in reef lowboys), shell-dwelling cichlids. Avoid fish that need significant vertical swimming space: angels, discus, and tall-swimming species are better suited to standard-height tanks.