How many fish can a 5 gallon tank support?

A 5 gallon fish tank can support between 5-10 small fish depending on the species. Some good options for a 5 gallon tank include:

  • Betta fish
  • Guppies
  • Tetras
  • Rasboras
  • Danios
  • Endler’s livebearers
  • White cloud mountain minnows

Factors that determine stocking capacity

There are several factors that determine how many fish a 5 gallon tank can safely support:

  • Fish size – Smaller fish take up less space and have lower bioloads.
  • Fish behavior – Aggressive or active fish require more space.
  • Filtration capacity – More powerful filters can handle higher bioloads.
  • Tank dimensions – Taller tanks allow more water volume.
  • Decorations and plants – More decor provides more hiding spaces.
  • Water changes – More frequent changes support higher stocking.

Recommended stocking levels

Here are some general recommendations for stocking a 5 gallon fish tank:

  • 1 betta fish
  • 6-8 small tetras, rasboras, or danios
  • 8-10 guppies, endler’s, or white cloud minnows
  • 1 dwarf gourami with 6-8 small fish
  • A pair of dwarf cichlids
  • 5-6 female bettas in a sorority

It’s best to start with a lower number of fish and gradually increase over time while closely monitoring water parameters. This allows the tank’s ecosystem to adjust and build up beneficial bacteria.

Stocking a 5 gallon tank for beginners

For beginner aquarists, here are some good options for stocking a 5 gallon tank:

  • 1 male betta
  • 6 neon tetras
  • 6 harlequin rasboras
  • 8 guppies (1 male and 7 females)

These fish are relatively hardy, readily available, and have low care requirements. A single betta with some snails or shrimp also makes for an easy beginner setup.

Ideal tank conditions

To support fish health, aim for the following water parameters in a 5 gallon tank:

  • Temperature between 72-82°F depending on species
  • pH between 6.5-7.5
  • KH between 3-8 dKH
  • Ammonia and nitrites at 0 ppm
  • Nitrates below 20 ppm

Use a quality heater, thermometer, liquid test kit, and filtration optimized for small tanks. Perform 25% weekly water changes and monitor parameters regularly.

Maximizing tank capacity

Here are some tips for maximizing fish stocking in a 5 gallon tank:

  • Choose small, peaceful community fish under 2 inches long
  • Use an efficient filter rated for 5-10 gallon tanks
  • Add live plants like java fern, anubias, mosses
  • Include hiding spots like rock caves and driftwood
  • Use a protein skimmer to remove waste
  • Perform 30-40% weekly water changes
  • Supplement with bacterial additives
  • Spread out feedings and don’t overfeed

Best fish for a 5 gallon tank

Here are some of the top fish species that can thrive in a properly maintained 5 gallon tank:

Betta Splendens (Betta Fish)

Bettas are a popular choice for small tanks given their bright colors, flowing fins, and minimal space requirements. Males must be kept alone, while females can be kept in sororities.

Ember Tetra

At just an inch long, ember tetras comfortably fit in groups of 6-8 in a 5 gallon tank. They add a nice pop of reddish-orange.

Neon Tetra

While slightly bigger at 1.5 inches, neons can still work well in a 5 gallon in a small school of 6 fish. They are very peaceful and add bright blue-red stripes.

Sparkling Gourami

These tiny gouramis grow to just over an inch long. A mating pair or small group makes an interesting focal point with their iridescent blue stripes.

Endler’s Livebearer

Endler’s are a smaller and more colorful strain of guppy, averaging under an inch long. A trio of 1 male and 2 females adds lively activity.

Celestial Pearl Danio

Also known as galaxy rasbora, these fish stay under 1 inch and have a stunning spotted pattern. A 5 gallon can hold 6-8.

Pygmy Corydoras

One of the few bottom dwellers suited to small tanks, pygmy cory cats reach just over an inch long. Keep 6 or more together.

Fish to avoid in a 5 gallon

Here are some fish that tend to be unsuitable for a 5 gallon tank:

  • Goldfish – Require at least 20 gallons and produce lots of waste.
  • Angelfish – Grow too large upwards of 6 inches tall.
  • Rainbowfish – Active swimmers that need at least 10 gallons.
  • Silver dollars – Grow over 6 inches and very active.
  • Cichlids – Most species grow too big or are too aggressive.
  • Large plecos – Produce lots of waste and can surpass 1 foot long.
  • Oscar fish – Need 75+ gallon tanks.
  • Tiger barbs – Nippy fish that should be in larger schools.
  • Discus fish – Require pristine water conditions and 50+ gallons.

It’s also best to avoid large snails like mystery snails that have high bioloads. Shrimp and smaller snails are better 5 gallon inhabitants.

Tank cycling and preparation

Before adding any fish, a 5 gallon tank needs to go through the nitrogen cycle. This establishes beneficial bacteria that convert ammonia into nitrite then nitrate. Cycling typically takes 4-8 weeks and involves:

  1. Setting up tank with filter and heater
  2. Adding ammonia source and testing levels
  3. Allowing bacteria colonies to grow and begin nitrification
  4. Changing water to limit nitrate accumulation
  5. Adding fish once cycled with low ammonia and nitrites

quick start products containing live bacteria can help speed up the process. Be patient and only add a few hardy fish at first when cycled. Slowly increase stocking over several weeks.

Maintenance routine

Once the tank is established, maintain it with:

  • 25-40% weekly water changes
  • Vacuuming gravel to remove debris
  • Filter media rinsing or replacement every 4-8 weeks
  • Testing water 1-2 times per week
  • Prompt water changes if ammonia or nitrites above 0
  • Cleaning algae off glass and decor
  • Pruning or thinning plants when overgrown
  • Feeding once or twice daily with variety

The smaller the tank, the more diligent the care required. But a 5 gallon aquarium can thrive with proper maintenance and an appropriate bioload.

Setting up the tank

Use these steps when setting up a new 5 gallon fish tank:

  1. Assemble clean tank on stable surface away from direct sunlight
  2. Install filter and heater suited for 5-10 gallons
  3. Wash gravel, plants, decorations before adding to tank
  4. Fill tank with dechlorinated water at proper temperature
  5. Add bacterial supplement to help cycling
  6. Consider adding floating or fast-growing stem plants
  7. Test water parameters and adjust until stable
  8. Introduce hardy fish after 4-8 weeks of cycling
  9. Slowly increase community fish over several weeks

Take time fully preparing the tank before buying fish. An uncycled tank can quickly turn deadly with ammonia spikes. Patience leads to long-term success.

Suitable tankmates

When stocking community fish, ensure any tankmates are compatible in terms of water parameters, space requirements, and temperament. Some tankmates suitable for a 5 gallon include:

  • Snails like nerites help eat algae
  • Ghost or cherry shrimp add color and activity
  • African dwarf frogs can live underwater with fish
  • Small bristlenose or otocinclus catfish for algae control
  • Amano shrimp are larger but also eat lots of algae
  • Bamboo shrimp or vampire shrimp filter feed

Avoid fin-nipping species that may harass fish with long fins like bettas. Make sure any additions fit within the tank’s bioload limit.

Aquascaping a small tank

Carefully aquascaping a 5 gallon tank creates an attractive vista and improves fish health. Useful techniques include:

  • Slope substrate towards back to create depth
  • Use taller plants in back, short in front
  • Arrange hardscape like rocks or driftwood aesthetically
  • Group plant species together in clusters
  • Leave open swimming areas for fish
  • Direct filter output to prevent disturbing substrate
  • Establish plant carpet like dwarf hairgrass
  • Use Java fern, anubias on hardscape to prevent burying

Plan your layout and aquascape before filling the tank and disturbing the substrate. Advance planning results in a more professional look.

Low-maintenance plants

Certain aquatic plants are well-suited to small tanks since they grow slowly and don’t require much trimming. Some top low-maintenance plants include:

  • Java fern
  • Anubias nana
  • Cryptocorynes
  • Java moss
  • Marimo moss balls
  • Amazon sword
  • Water wisteria
  • Hornwort
  • Duckweed

Focus on slow growers that won’t quickly overrun the tank. Attach plants like java fern to rocks or driftwood instead of planting in the substrate.

Best filter for a 5 gallon

Filters optimized for small tanks include:

  • Sponge filters – Inexpensive and provide lots of surface for bacteria
  • Internal filters – Designed for tanks under 10 gallons
  • Mini canisters – Low flow good for bettas
  • HOB filters – Low profile hang-on-back models available
  • Nano filters – Very compact for nano tanks

Aim for a filter rated for 5-15 gallons that provides gentle water movement without too much turbulence. Moderate flow helps oxygenate the tank and distribute heat.

Heater options

Small aquarium heaters suitable for 5 gallons include:

  • 25-50 watt submersible heaters
  • Low wattage preset heaters
  • Mini mat heaters adhered under tank
  • Small sponge heaters built into filter

Select an adjustable heater matched to tank volume. Preset heaters maintain a fixed temperature. Always use a thermometer to monitor the actual temperature.


A 5 gallon fish tank can comfortably support a modest community of small fish species such as bettas, tetras, guppies, and rasboras. Limit fish length to under 2 inches and follow general stocking guidelines. Filter, heat, plant, and aquascape the tank appropriately for the fish species. Perform diligent tank maintenance and water changes to maintain water quality. Test parameters regularly and don’t overstock. With conscientious care and stocking, a 5 gallon tank can thrive for years.

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