Best Fish for a 5 Gallon Fish Tank
These species are well-suited to a 5-gallon aquarium in terms of adult size, bioload, and behaviour.
Betta Fish (1 male)
The definitive 5-gallon fish. One male betta thrives with a heater, gentle filter, and plants.
Cherry Shrimp (10β15)
A shrimp colony is perfect: low bioload, entertaining to watch, excellent algae cleaners.
Nerite Snails (2β3)
Algae-grazing snails that complement a betta or shrimp tank without overcrowding.
Endler's Livebearers (5β6)
Tiny, active, and colourful β endlers are one of the few schooling fish safe in 5 gallons.
5 Gallon Tank Dimensions & Weight
A standard 5-gallon aquarium measures about 16 Γ 8 Γ 10 inches (41 Γ 20 Γ 25 cm, L Γ W Γ H) and holds roughly 19 litres. Water weighs about 8.34 lb per US gallon (USGS water-density reference), so once you add glass, substrate and rock, expect a filled weight of around 65 lb. That is fine for a sturdy desk or dresser, but keep it off a wobbly shelf and out of direct sunlight, which drives algae fast in a small volume.
Best for: a single betta, a dwarf shrimp colony, or a small group of nano fish such as chili rasboras. Not for: goldfish, tetra schools, or anything that needs swimming length.
Fish to Avoid at This Size
These species require more space, produce too much waste, or have specific needs that a 5-gallon cannot meet long-term.
Stocking & Water Change Guidelines
Stocking: In 5 gallons stick to a single species. The nitrogen cycle is fragile at this volume β one betta or a shrimp colony, not both.
Water changes: 25β30% weekly for a betta; 15β20% every 10 days for a shrimp-only setup.
Cycle time: 3β4 weeks with a bacteria starter and daily ammonia dosing.
Equipment & Setup Cost
| Equipment | Recommendation |
|---|---|
| Filter | Small sponge filter or hang-on-back rated up to 10 gal (e.g., Aqueon QuietFlow 10). Low flow is critical β bettas dislike strong currents. |
| Heater | 25 W adjustable submersible heater (Eheim JΓ€ger or Fluval E25). |
| Lighting | 5β10W LED, 6β8 hrs per day. Low-light plants (java fern, anubias) thrive at this level. |
| Estimated Setup Cost | $50β$120 all-in (tank, filter, heater, thermometer, conditioner, lid, light). |
Frequently Asked Questions
How many fish can you put in a 5 gallon tank?
For a 5-gallon tank, a single betta fish is the ideal choice β it gets the full territory it needs. If you prefer community fish, a colony of 10β15 cherry shrimp or 5β6 endler's livebearers are the safest options. Avoid putting multiple species in a 5-gallon tank, as the small water volume makes parameter swings dangerous.
Is a 5 gallon tank good for a betta fish?
Yes β a 5 gallon tank is the recommended minimum for a single male betta fish. It provides enough water volume to maintain stable temperature and water quality, and enough space for the betta to swim, explore, and display its fins. Tanks smaller than 5 gallons make it difficult to keep ammonia and nitrite at 0 ppm.
What filter should I use for 5-gallon tank?
Use a sponge filter or a small hang-on-back (HOB) filter rated up to 10 gallons. Aim for a turnover of about 3β5Γ the tank volume per hour (15β25 GPH). Avoid filters designed for large tanks β the flow will be too strong for bettas and too disruptive for shrimp.
Can goldfish live in 5-gallon tank?
No. A single fancy goldfish needs a minimum of 20 gallons; a single-tailed (comet) goldfish needs 55+ gallons. Goldfish produce a large amount of ammonia and grow to 6β12 inches. Keeping goldfish in a 5 gallon tank causes chronic stress, stunted growth, and shortened lifespan.