How many black tetras for a 10 gallon?

When it comes to stocking a 10 gallon aquarium, black tetras are an excellent choice for these smaller setups. But how many of these fish can you keep in a tank this size? There are a few factors to consider when determining the ideal number of black tetras for a 10 gallon aquarium.

Quick Answer

For a 10 gallon tank, we recommend keeping between 6 to 8 black tetras. This number provides a good balance between having an active school of fish and avoiding overcrowding in a small aquarium. The actual number you can house may vary slightly based on additional tank inhabitants.

Black Tetra Care Guide

Before determining tank numbers, it’s important to understand some background on keeping black tetras. Here is a quick care guide for these fish:

  • Scientific Name: Gymnocorymbus ternetzi
  • Adult Size: Around 2 inches
  • Ideal Tank Size: 10 gallons minimum
  • Temperature Range: 72°F – 79°F
  • pH Range: 6.0 – 7.5
  • Hardiness: Easy to care for, good for beginners
  • Lifespan: Up to 6 years with proper care
  • Diet: Omnivore, eats flakes, pellets, live/frozen foods
  • Temperament: Peaceful schooling fish

Key takeaways include their small adult size, schooling nature, and moderate care needs. This profile provides a baseline for understanding general housing requirements.

10 Gallon Tank Considerations

When stocking any 10 gallon tank, there are a few important considerations to ensure healthy fish and aquarium conditions:

  • Avoid overstocking – 10 gallons gives limited space
  • Select peaceful community fish
  • Choose species with similar water parameter needs
  • Include 6-8 individuals of each schooling species
  • Aim for 1 inch of adult fish per gallon of water
  • Supplement filtration to handle bioload
  • Perform regular water changes and maintenance

Following these guidelines will lead to a thriving, balanced 10 gallon aquarium.

Black Tetra Group Size

Black tetras thrive in groups of 6 or more. This provides security, encourages natural schooling behavior, and prevents stress in these community fish. Groups smaller than 6 can lead to issues like:

  • Hiding and reclusive behavior
  • Increase aggression and fin nipping
  • Poor coloration
  • Lack of activity
  • Greater susceptibility to disease

For general schooling fish like tetras, bigger is better when it comes to group size and numbers. But tank size always limits group size potential, especially in smaller aquariums.

Recommended Black Tetra Numbers for 10 Gallons

Based on the 10 gallon stocking considerations and black tetra care and behavior needs, here are the recommended numbers for a 10 gallon tank:

  • 6 black tetras
  • 7 black tetras
  • 8 black tetras

This range allows for a proper school size without exceeding the general one inch of fish per gallon for tetras. Going below 6 black tetras risks schooling issues and stress. Exceeding 8 tetras can overload the bioload capacity of a 10 gallon tank.

6 Black Tetras

6 black tetras is the minimum recommended number for a 10 gallon aquarium. This group size provides security while leaving adequate swimming area. With their small size, this allows sticking close to the one inch of fish per gallon rule.

7 Black Tetras

Increasing to 7 black tetras adds additional schooling dynamics while still avoiding overcrowding. This provides more interaction and activity to enhance their natural behaviors. The extra inch of fish remains safely within tank capacity.

8 Black Tetras

A group of 8 black tetras fully maximizes numbers for a 10 gallon tank before risking issues. This creates a vibrant school that is active and entertaining to watch. Go above 8 fish and water quality can struggle to keep up.

Other Tank Inhabitants

The above numbers are based on housing black tetras by themselves. Adding other fish species or tank mates reduces the number of tetras the aquarium can support.

Some common options compatible with black tetras include:

  • Peaceful nano fish like guppies, neon tetras, endlers, and celestial pearl danios
  • Invertebrates like cherry shrimp, nerite snails, mystery snails
  • Bottom dwellers like corydoras catfish and otocinclus

Here are the recommended black tetra numbers when adding other inhabitants:

  • 5 black tetras with 1-2 nano fish or 5-10 small inverts
  • 4 black tetras with 3-4 nano fish or 5-10 small inverts
  • 4 black tetras with 2-3 small bottom dwellers

Make sure to research compatibility, space requirements, and the bioload of any added tankmates. Focus on creates a peaceful community with shared water needs.

10 Gallon Black Tetra Tank Setup Tips

In addition to stocking levels, tank setup is key to black tetra health and reducing aggression. Here are important guidelines for a 10 gallon black tetra aquarium:

  • Planted aquarium with live plants for hiding spots
  • Soft sandy or fine gravel substrate
  • Dim lighting to mimic natural habitat
  • Water movement from filter outflow
  • Addition of floating plants for cover
  • Natural wood, rocks, and decor for breaks in open water
  • Low water flow from filter

Focus on a simple, peaceful environment with plenty of plants and coverage. Perform regular partial water changes and filter maintenance to keep water clean.

Feeding Black Tetras

Black tetras are omnivorous and will accept a wide variety of foods. Offer a mixed diet to keep fish healthy and colors vibrant. Feed twice daily in small amounts that fish can consume within a few minutes. Good diet staples include:

  • Quality flakes and micro pellets
  • Live, frozen, freeze-dried brine shrimp, bloodworms
  • Daphnia, cyclops, mosquito larvae
  • Vegetables like zucchini, spinach, shelled peas

Vary their diet between prepared dried foods and supplemental live or frozen options a few times per week. This helps recreate their natural diet and grazing behaviors in the home aquarium.

Black Tetra Care Guide

While black tetras are hardy fish, you still need to provide proper care. Maintain the following in your 10 gallon black tetra tank:

  • 72°F to 79°F temperature range
  • pH between 6.0 to 7.5
  • Minimal water flow and low currents
  • 0 ammonia, 0 nitrites, and low nitrates
  • Weekly 15-25% partial water changes
  • Proper filtration from a hang-on-back or canister filter
  • Live plants and aquascaping that provides security

Test water parameters weekly and adjust as needed to maintain an optimal environment. Quarantine and properly acclimate any new fish additions.

Signs of Stress in Black Tetras

Look out for these signs of stress, aggression, or illness in your black tetra aquarium:

  • Loss of color or faded black stripes
  • Clamped fins
  • Hiding or reclusive behavior
  • Rapid breathing
  • Loss of appetite
  • Bullying or attacking tankmates
  • Swimming issues or floating
  • Skin lesions or raised scales

Identify and resolve the underlying issue, whether it relates to water parameters, aggression, or disease. Address promptly before health declines further or leads to mortalities.


When stocking black tetras in a 10 gallon aquarium, go with 6 to 8 fish for a healthy active school. Reduce numbers if adding additional species as tankmates. Follow housing, feeding, and care guidelines tailored to their needs. Monitor fish closely and have a quarantine tank ready for illnesses. With some planning and proper maintenance, a group of these lively tetras makes an excellent addition to smaller community aquariums.

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