The Marineland Contour 5 Gallon Kit is a self-contained nano aquarium designed for small freshwater fish setups, bettas, shrimp, and nano fish. It comes with a hidden rear filtration system, a clip-on LED light with adjustable settings, and a curved front panel that gives it a distinctive, modern look. For its price ($65-85 depending on where you buy it), it's one of the more polished entry-level nano kits available, though like most all-in-one systems it has a few limitations worth knowing about before you buy.
This review covers what the Contour 5 includes, how well the components perform, what I'd upgrade or change, which fish and setups work best in it, and how it compares to competing nano kits at a similar price point.
What Comes in the Marineland Contour 5 Gallon Kit
The box includes the tank itself (curved glass front, black plastic rear filter housing), a clip-on LED light fixture, filter cartridges (Marineland's rite-size Z cartridge), and a foam insert for the filtration chamber. That's it. No heater, no thermometer, and no substrate.
The curved front glass is 5mm thick and produces a clean, distortion-free view that's actually one of the better features of this tank. The black rear panel hides the filtration compartment and equipment neatly, which gives the tank a cleaner look than most competitors at this size.
The tank dimensions are approximately 11.8 x 11.8 x 17.3 inches (L x W x H). The tall, narrow format works well for bettas that prefer some vertical swimming room and is an interesting alternative to the typical wide, shallow nano designs.
The LED Light
The clip-on LED provides two settings: a bright white/blue daylight mode and a lower-intensity "moonlight" blue mode. The daylight mode is bright enough for low-to-medium light plants like Java fern, Anubias nana, and Java moss. It won't grow high-light plants like glossostigma or some stem plants effectively, but for a beginner planted tank with easy species it works fine.
The clip mount attaches to the rear of the tank and positions the light directly over the water. One practical downside: the light doesn't have a timer, so you need either to manually switch it or use a smart plug (a Kasa KP115 costs about $18) to automate the photoperiod.
How the Filtration System Performs
The Marineland Contour uses a rear filtration chamber accessed through a removable top panel. The filter pulls water through slots at the back of the display section, runs it through a foam pre-filter stage and then through a Marineland Rite-Size Z cartridge, and returns clean water through a surface skimmer slot near the top.
The flow rate is gentle, around 45 GPH. This is appropriate for bettas (which are stressed by strong flow) and shrimp but may be insufficient for heavy stocking. The surface agitation the return outlet creates is enough for adequate oxygen exchange in a lightly stocked 5-gallon tank.
The Cartridge System
The included filter cartridges use a carbon-embedded floss cartridge design. The cartridges work adequately but have a known limitation: replacing the cartridge when it's dirty removes the beneficial bacteria that have colonized it. This resets part of your biological filtration each time you change the media.
The better approach, which many Contour owners use, is to leave the cartridge in place longer (only replace when it's visibly falling apart) and add a small piece of biological media to the rear chamber. A couple of ceramic rings or a small sponge insert kept in the rear chamber provides stable bacterial colonization that doesn't need replacing. This significantly improves the biological filtration capacity for the size.
For a broader look at aquarium equipment options at different price points, the Top 5 Aquarium Equipment guide covers what experienced hobbyists reach for most often.
What You'll Need to Add
The Marineland Contour 5 Gallon Kit is a good starting point but you'll need a few additional items to set up a functional aquarium.
Heater
The kit includes no heater, and for tropical fish (including bettas, which need 76-82°F) a heater is not optional. The Cobalt Aquatics Flat Neo-Therm 25W is purpose-built for nano tanks and maintains temperature within +/- 0.5°F. It fits neatly inside the rear filter chamber of the Contour 5, keeping it hidden from view. The Eheim Jager 25W is another solid option, though it's slightly larger and may be visible in the display section if you can't fit it in the rear chamber.
Avoid the no-name heaters sometimes bundled in budget nano kits. Temperature accuracy is the most important spec in a heater and cheap heaters frequently fail to hold stable temperature.
Thermometer
A stick-on external thermometer like the Coralife Digital Thermometer ($10-12) gives you a continuous temperature reading without inserting anything into the tank. Digital inline thermometers are more accurate if you prefer.
Substrate
The Contour 5 works with any standard aquarium substrate. Eco-Complete or Fluval Stratum (about 4-5 lbs for a 5-gallon tank) support planted tanks well. Pool filter sand at $7-10 for a 50 lb bag is an inexpensive, clean-looking option for a non-planted betta setup.
Best Fish and Setups for the Marineland Contour 5 Gallon
Single Betta
A single betta fish in a planted 5-gallon is the most popular use case for this tank, and one where the Contour performs well. The gentle flow rate doesn't buffet the betta's fins, the tall format gives vertical swimming space, and a small heater in the back chamber maintains temperature easily. Java fern attached to the included black background rock or a small piece of driftwood, with a couple of Anubias nana plants, creates a natural environment with minimal maintenance.
Bettas are territorial and should be kept alone in this tank.
Shrimp and Nano Fish
A community of Neocaridina shrimp (cherry shrimp, blue dream shrimp) thrives in a 5-gallon planted setup. Add a small school of 6-8 chili rasboras or ember tetras for a peaceful nano community. The gentle filtration flow is appropriate for shrimp, which are sensitive to strong currents.
Avoid active fish like danios or guppies that need more swimming room, and skip any fish that grow larger than 1.5 inches (they'll quickly outgrow a 5-gallon).
Quarantine Tank
The Contour 5 makes an excellent quarantine tank for new fish before introducing them to a larger main tank. Its compact size, easy cleaning access through the top, and self-contained filtration make it practical for short-term quarantine use.
Comparing to Competing 5-Gallon Nano Kits
Aqueon LED MiniBow 5
The Aqueon MiniBow 5 ($50-60) is slightly cheaper with a more rounded aesthetic. Its filtration is functional but the cartridge system has the same limitations as the Marineland. The LED in the MiniBow is less adjustable and doesn't have a moonlight mode. Overall the Marineland Contour edges it out on build quality and aesthetics.
Fluval Spec V 5-Gallon
The Fluval Spec V ($80-100) is the main alternative and a step up overall. It includes a more powerful return pump (65 GPH vs. 45 GPH in the Contour), a better LED with adjustable brightness, and a superior biological filtration design. The tradeoff is that the stronger flow can stress bettas more than the Contour. The Spec V is the better choice for planted tanks or shrimp setups where stronger circulation and better lighting matter; the Contour is the better betta tank.
Check out our guide to Best Aquarium Equipment for a broader look at nano and full-size tank options.
FAQ
Does the Marineland Contour 5 Gallon need a heater? Yes. The kit doesn't include one, and tropical fish including bettas need water temperatures between 76-82°F. Without a heater in most homes, the tank will run at room temperature, which drops too low in fall and winter. The Cobalt Aquatics Flat Neo-Therm 25W fits cleanly in the rear filter chamber and keeps temperature stable without being visible.
What fish can I keep in a 5-gallon aquarium? Suitable options: one betta fish (alone), a colony of dwarf shrimp (10-20), a small school of nano fish like chili rasboras, ember tetras, or pygmy corydoras (6-8 fish). Avoid cichlids, larger tetras, goldfish, and any fish over 2 inches at adult size.
How often does the Marineland Contour 5 need water changes? For a single betta with light feeding, a 25-30% weekly water change keeps water quality good. For a shrimp-only tank with live plants, every 2 weeks is often sufficient. Nano tanks accumulate waste faster proportionally than larger tanks because of lower total water volume, so consistent small changes are better than occasional large ones.
Is the Marineland Contour 5 suitable for saltwater? No. It's designed for freshwater and does not include a protein skimmer, circulation pump, or lighting spectrum appropriate for saltwater. For a saltwater nano, the Innovative Marine Nuvo Fusion 10 or the Fluval Sea EVO XII are purpose-built options with appropriate equipment included.
Conclusion
The Marineland Contour 5 Gallon Kit is a genuinely well-designed nano tank at its price point. The curved glass, hidden filtration, and adjustable LED make it one of the more attractive and practical all-in-one options in the under-$100 category. The main things to add are a 25-watt nano heater and a stable biological media insert in the rear chamber to improve filtration. Set up correctly with a single betta or a small shrimp colony, it runs reliably with minimal maintenance and looks sharp on a desk or countertop.