Quick answer: Most pet-store tetras are small schooling characins. Adult size, not stripe color, should set tank length. Keep one species in a real school and match the published maximum length.
These 20 common store tetras are small schooling characins with FishBase maxima from 2.0 to 13.2 centimeters. This page compares 20 tetra species from published records and we did not keep, breed, or age these fish.
How we chose these 20 types
A species had to pass two gates before it entered this page.
Our research team analyzed FishBase summaries for fish sold under a stable U.S. common name, and we kept a species only when FishBase published a maximum length. We left out dyed color morphs sold as separate types, Mexican cave tetras, and mixed bags with no species name.
That rule is why Buenos Aires tetra appears here, because FishBase lists its maximum at 13.2 centimeters total length. Many store cards skip that record and treat the fish as a mid-size tetra.
We also skip “best tetra” ranks, because size and tank length are the useful split.
The 20-species size map
FishBase maxima for these 20 types span 2.0 to 13.2 centimeters. Ten species sit under 4.0 centimeters, and three sit above 7.0 centimeters.
Use the table to pick a size band first, then read the care notes for that band.
Standard length (SL) stops before the tail fin, while total length (TL) includes the tail. Do not mix those numbers as if they were the same measure.
| Common name | Scientific name on FishBase | FishBase maximum | Measure |
|---|---|---|---|
| Ember tetra | Hyphessobrycon amandae | 2.0 cm | SL |
| Green neon tetra | Paracheirodon simulans | 2.0 cm | SL |
| Neon tetra | Paracheirodon innesi | 2.5 cm | SL |
| Flame tetra | Hyphessobrycon flammeus | 2.6 cm | SL |
| Cardinal tetra | Paracheirodon axelrodi | 3.0 cm | SL |
| Black neon tetra | Hyphessobrycon herbertaxelrodi | 3.2 cm | SL |
| Glowlight tetra | Hemigrammus erythrozonus | 3.3 cm | TL |
| Penguin tetra | Thayeria boehlkei | 3.6 cm | SL |
| Lemon tetra | Hyphessobrycon pulchripinnis | 3.8 cm | SL |
| Silvertip tetra | Hasemania nana | 3.8 cm | SL |
| Serpae tetra | Megalamphodus eques | 4.0 cm | SL |
| Emperor tetra | Nematobrycon palmeri | 4.2 cm | SL |
| Pristella tetra | Pristella maxillaris | 4.5 cm | TL |
| Rummy-nose tetra | Petitella rhodostoma | 5.0 cm | TL |
| Bloodfin tetra | Aphyocharax anisitsi | 5.5 cm | TL |
| Diamond tetra | Makunaima pittieri | 6.0 cm | SL |
| Red-eye tetra | Bario sanctaefilomenae | 7.0 cm | SL |
| Black skirt tetra | Gymnocorymbus ternetzi | 7.5 cm | SL |
| Congo tetra | Phenacogrammus interruptus | 8.0 cm male / 6.0 cm female | TL |
| Buenos Aires tetra | Psalidodon anisitsi | 13.2 cm | TL |
FishBase also flags extra size notes on a few rows.
- Glowlight tetra: FishBase calls 3.3 centimeters questionable and also cites 4 centimeters total length.
- Penguin tetra: FishBase also cites reports of 6 centimeters total length.
- Lemon tetra: FishBase lists a published weight of 1.36 grams.
- Silvertip tetra: FishBase lists a published weight of 1.3 grams.
Convert only after you know the measure type.
- 2.0 cm is about 0.8 inch.
- 8.0 cm is about 3.1 inches.
- 13.2 cm is about 5.2 inches.
Nano tetras at or under 3 centimeters
These five types stay short enough for a planted nano tank if the school is the only midwater fish.
FishBase maxima in this band run from 2.0 to 3.0 centimeters standard length.
- Ember and green neon tetras both reach 2.0 cm SL. FishBase dates the ember tetra’s IUCN Least Concern listing to 7 November 2018.
- Neon tetra reaches 2.5 cm SL, and flame tetra reaches 2.6 cm SL.
- Cardinal tetra reaches 3.0 cm SL and still belongs with this nano set for tank mates.
A planted floor helps these small bodies hold color and hide. Our guide to the best substrate for a planted aquarium covers root-friendly bases.
Do not add a large tetra from the bottom of the table to this tank. Buenos Aires tetra’s FishBase maximum is 6.6 times the ember tetra’s 2.0 centimeters.
Mid-size tetras from 3 to 6 centimeters
These types need more swim length than a cube kit can give.
FishBase asks for groups of 5 or more on several of these species, and it lists tank lengths of 60 or 80 centimeters.
- Glowlight tetra reaches 3.3 cm TL, and FishBase lists a 60 cm tank plus groups of 5 or more.
- Penguin tetra reaches 3.6 cm SL with the same 60 cm tank and group note. FishBase says its eggs hatch in about 20 to 24 hours.
- Silvertip tetra reaches 3.8 cm SL, and FishBase lists a 60 cm tank plus groups of 5 or more.
- Lemon tetra reaches 3.8 cm SL in males and 3.6 cm SL in females.
- Serpae tetra reaches 4.0 cm SL, and FishBase dates its IUCN Least Concern listing to 4 March 2021. FishBase also notes fin biting when too many fish crowd a feeding spot.
- Emperor tetra reaches 4.2 cm SL. FishBase lists pH 5.0 to 8.0, groups of 5 or more, and an 80 cm tank.
- Pristella, rummy-nose, and bloodfin tetras reach 4.5 cm TL, 5.0 cm TL, and 5.5 cm TL.
- Diamond tetra reaches 6.0 cm SL, and FishBase lists groups of 5 or more plus an 80 cm tank.
- Black neon tetra reaches 3.2 cm SL, so plan it with the glowlight group, not with Congo tetras.
Sixty centimeters is about 24 inches, and eighty centimeters is about 31 inches.
The Fluval Flex Aquarium Kit, 15 US Gal is 16 inches long per Fluval’s U.S. product page. That 41 centimeter length is shorter than FishBase’s 60 centimeter minimum for glowlight, penguin, and silvertip tetras.
Use the Flex 15 only for the nano band, and do not stretch mid-size schools into a 16-inch box.
Aquarium driftwood gives these midwater fish a break line and a dimmer backdrop, but it does not replace tank length.
Large tetras that need long tanks
Four types in this set outgrow a short community box and need real frontage.
FishBase maxima here are 7.0 centimeters standard length and up.
- Red-eye tetra: 7.0 cm SL. FishBase lists groups of 5 or more and an 80 cm tank.
- Black skirt tetra: 7.5 cm SL.
- Congo tetra: 8.0 cm TL for males and 6.0 cm for females. FishBase lists groups of 5 or more and a 100 cm tank. It also lists pH 6.0 to 8.0, hardness 5 to 19 dH, and 23 to 26°C.
- Buenos Aires tetra: 13.2 cm TL. That is the longest published record in this set.
One hundred centimeters is about 39 inches, and Congo tetras need that frontage on FishBase’s aquarium note.
Do not house these fish with African cichlid types that want hard, alkaline water. Congo tetra’s FishBase pH band starts at 6.0, which is a different chemical plan.
Black skirt and Buenos Aires tetras are deep-bodied and fast, so they can crowd smaller neons at feeding time. Keep them in their own size class.
Care rules that hold across types
School size and water checks matter more than stripe pattern.
FishBase repeats the same social note on glowlight, penguin, silvertip, emperor, diamond, red-eye, and Congo tetras: keep groups of 5 or more.
Use that as a floor, not a ceiling. One leftover tetra from a bag of six is a stressed fish, not a “centerpiece.”
API’s Freshwater Master Test Kit page says to test weekly, and it also states that a pH of 7.0 is neutral.
- Test ammonia, nitrite, nitrate, pH, and high-range pH on the schedule the API booklet lists.
- Keep the four included test tubes clean so color cards stay readable.
- Do not guess pH from the fish’s color.
Seachem’s Prime page states the dose in plain numbers.
- Use 1 capful (5 mL) for each 50 U.S. gallons of new water.
- Each cap thread is about 1 mL.
- Prime can be dosed every 24 to 48 hours.
- It binds ammonia, nitrite, and nitrate for up to 48 hours.
- If ammonia or nitrite is above 2 ppm, Seachem says you may use up to 5 times the normal dose.
Hikari’s Tropical Micro Pellets page names tetras as a target fish, and the guaranteed analysis lists 43% minimum crude protein and 7% minimum crude fat.
- Feed two to three times daily.
- Give only what fish finish in a few minutes.
Fluval’s Bug Bites Tropical Granules page lists 40.0% minimum crude protein and 12.5% minimum crude fat. Granules are 1.4 to 2.0 mm, and Fluval says feed what fish eat in two minutes, two or three times daily.
Pick one daily food and stay consistent, and do not stack both pellets at every feeding.
Gear compared by listed maker specs
Match kit length and food size to the species band, not to the box art.
The table uses attributes the makers publish. It is not a rank list and it has no prices.
| Product | Maker | Listed use | Key listed spec |
|---|---|---|---|
| Flex Aquarium Kit, 15 US Gal | Fluval | Freshwater display kit | 15 U.S. gal / 57 L; 16 × 15 × 15 in; 132 U.S. GPH; 10.8 W; 7500 K LED |
| Freshwater Master Test Kit | API | Weekly freshwater tests | Four test tubes; pH 7.0 marked as neutral; tests ammonia, pH, high-range pH, nitrite, nitrate |
| Prime | Seachem | Fresh and saltwater conditioner | 5 mL per 50 U.S. gal; binds waste up to 48 hours |
| Tropical Micro Pellets | Hikari | Daily diet for tetras and other small-mouth fish | 43% min protein; 22 g, 45 g, and 80 g packs |
| Bug Bites Tropical Granules, 4.4 oz | Fluval | Daily tropical diet | 40.0% min protein; 1.4–2.0 mm slow-sinking granules |
Fluval’s Flex 15 page lists 54 LEDs and 2450 lumens, so that light is for plants and color, not for a Congo school. The tank is still 16 inches long.
Hikari packs start at 0.77 oz (22 g), which is enough to check pellet size on ember and neon mouths. Fluval’s 4.4 oz / 125 g Bug Bites bag is the mid shop size on that U.S. page. Seachem lists Prime in 50 mL through 4 L bottles, so dose from the 5 mL-per-50-gallon rule, not bottle size.
FAQ
How many types of tetras are there in pet stores?
Stores sell far more than 20 labels if you count color forms. This page covers 20 species that have both a common U.S. name and a FishBase maximum length. That is a buying set, not a full characin count.
What is the smallest common tetra?
FishBase lists both ember tetra and green neon tetra at 2.0 centimeters standard length. Those are the shortest maxima in this set. Neon tetra is next at 2.5 centimeters standard length.
What is the largest tetra on this list?
Buenos Aires tetra has the longest FishBase record here at 13.2 centimeters total length. Congo tetra is next among common stock, at 8.0 centimeters total length for males.
How many tetras should I keep together?
FishBase’s aquarium notes for glowlight, penguin, silvertip, emperor, diamond, red-eye, and Congo tetras say groups of 5 or more. Use five as the published floor. A larger school is safer in a tank that already meets the listed length.
Can I keep tetras in a 15-gallon cube?
Fluval lists the Flex 15 at 16 inches long. FishBase asks for 60 centimeters, about 24 inches, for glowlight, penguin, and silvertip tetras. Limit a 16-inch tank to the nano band: ember, green neon, neon, flame, and cardinal.
Do tetras need a planted tank?
They do not require plants to meet a FishBase length record, but small types use plants as cover. If you plant the tank, start with a substrate made for roots.
Can I mix tetras with African cichlids?
Not as a default plan, because Congo tetra’s FishBase pH range is 6.0 to 8.0 with 23 to 26°C water. Many African lake cichlids are kept harder and more alkaline than that band, so keep the two groups on separate chemistry plans.
