Penguin tetra care guide
Also called: False penguin tetra, Hockey stick tetra, Blackline penguinfish, Penguin fish
The penguin tetra is a lively, 2 in (5 cm) shoaling fish with a black stripe that bends into the lower tail like a hockey stick, and it swims slightly head-up. Keep six or more in a 20 gallon (76 L) tank with a lid.
Penguin tetras need a tank of at least 20 gallons (76 L), a group of 6 or more, and water at 22–28°C (72–82°F) with a pH of 6–7.5. They grow to about 5 cm (2 in) and are peaceful.
Plan a tank with penguin tetrasSee all tank mates
Penguin tetra quick facts
| Scientific name | Thayeria boehlkei |
|---|---|
| Family | Acestrorhamphidae |
| Origin | Upper Amazon in Peru and the Rio Araguaia, Brazil (most are farm-bred) |
| Adult size | 5 cm (2 in) |
| Minimum tank | 20 gallons (76 L), at least 60 cm (24 in) long |
| Temperature | 22–28°C (72–82°F) |
| pH | 6–7.5 |
| Hardness (GH) | 3–15 dGH |
| Group size | 6 or more (shoaling fish) |
| Temperament | Peaceful |
| Swims at | Middle |
| Diet | Omnivore |
| Care level | Easy |
| Lifespan | 3–5 years |
| Safe with shrimp? | Mostly (eats baby shrimp) |
| Safe with plants? | Yes |
- Known jumper: keep a tight-fitting lid.
Tank setup
Use at least a 20 gallon (76 L) tank about 24 in (60 cm) long for a group of six, and go bigger for a larger shoal. Plant the back and sides, keep open water in the middle and add a few floating plants. Fit a tight lid, because startled fish can jump.
How many penguin tetras in a tank?
The smallest common tank that suits penguin tetras is a 20 gallon. Here is roughly how many fit in each size when they are the only fish, based on adult size and waste output. Leave room if you want tank mates.
| Tank | Penguin tetras (alone) |
|---|---|
| 3 gallon | Too small |
| 5 gallon | Too small |
| 10 gallon | Too small |
| 15 gallon | Too small |
| 20 gallon | 6–19 |
| 20 gallon long | 6–19 |
| 29 gallon | 6–28 |
| 40 gallon | 6–39 |
| 55 gallon | 6–53 |
| 75 gallon | 6–73 |
| 125 gallon | 6–121 |
What you need for penguin tetras
Sized for a 20 gallon tank, the smallest common size that suits a group of 6 penguin tetras. For a different tank or a mix of fish, use the stocking calculator for a list sized to your plan.
Tank and equipment
- 20 gallon aquarium (tank or kit) (opens Amazon in a new tab)Bigger tanks are more stable and easier for beginners. How to choose
- Aquarium stand for 20 gallons (opens Amazon in a new tab)The water alone weighs about 167 lb (76 kg), before glass, gravel and rock. How to choose
- Adjustable heater, 75 W (opens Amazon in a new tab)Holds about 77 °F (25 °C) in a room at 65 °F (18 °C). How to choose
- Aquarium thermometer (opens Amazon in a new tab)Check it daily: heaters can fail stuck on or off. How to choose
- Hang-on-back filter rated 80–120 GPH (opens Amazon in a new tab)Community tank: 4–6 times the tank volume per hour. How to choose
- About 35 lb of aquarium gravel (opens Amazon in a new tab)Enough for a layer about 2 in (5 cm) deep. Smooth gravel suits most community fish. How to choose
- Water conditioner (dechlorinator) (opens Amazon in a new tab)Removes chlorine and chloramine from tap water. Seachem Prime is a popular, concentrated choice. How to choose
- Liquid test kit (ammonia, nitrite, nitrate, pH) (opens Amazon in a new tab)Liquid kits are more accurate than strips. The API Freshwater Master Test Kit is the common choice. How to choose
- Gravel vacuum (siphon) (opens Amazon in a new tab)Cleans the gravel and does the water change in one go. How to choose
- LED aquarium light, about 24 in long (opens Amazon in a new tab)Match the light to the tank length. Basic LEDs grow easy plants. How to choose
Food and extras for penguin tetras
- Micro pellets or flakes for small fish (opens Amazon in a new tab)Small enough for tetras, rasboras and other nano fish.
- Tight-fitting lid for a 20 gallon tank (opens Amazon in a new tab)Penguin tetra can jump out of an open tank.
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Water parameters
Keep it at 22–28 °C (72–82 °F), pH 6.0–7.5 and about 3–15 dGH. Farm-bred fish adapt well, but they do not tolerate ammonia, nitrite or high nitrate. Change part of the water every week.
Best tank mates for penguin tetras
These popular species share penguin tetras' water needs and temperament. See the full list of 95 good matches.
Cherry shrimp
3 cm (1.2 in) · 20–27°C (68–81°F)
Nerite snail
2.5 cm (1 in) · 22–27°C (72–81°F)
Neon tetra
3.5 cm (1.4 in) · 21–25°C (70–77°F)
Panda corydoras
4.5 cm (1.8 in) · 21–25°C (70–77°F)
Bristlenose pleco
12 cm (4.7 in) · 22–26°C (72–79°F)
Bronze corydoras
7 cm (2.8 in) · 21–26°C (70–79°F)
Zebra danio
5 cm (2 in) · 18–25°C (64–77°F)
Assassin snail
2.5 cm (1 in) · 22–27°C (72–81°F)
Avoid keeping penguin tetras with
- Oscar: Oscar can eat penguin tetras: they're small enough to fit in its mouth once it's grown.
- Bala shark: Bala shark can eat penguin tetras: they're small enough to fit in its mouth once it's grown.
- Chinese algae eater: Chinese algae eater is aggressive and will bully or injure peaceful penguin tetras.
- Convict cichlid: Convict cichlid is aggressive and will bully or injure peaceful penguin tetras.
- Electric blue acara: Electric blue acara can eat penguin tetras: they're small enough to fit in its mouth once it's grown.
- Electric yellow cichlid: Electric yellow cichlid is a Lake Malawi cichlid. It needs a Lake Malawi tank: hard, alkaline water (pH 7.5–8.5), plenty of rockwork and other cichlids from the same lake. Penguin tetras don't belong in that setup.
Feeding
An unfussy omnivore. Feed a quality flake or micro pellet as the staple. Add frozen or live bloodworm, daphnia and brine shrimp a few times a week. Two or three small meals a day work better than one large one.
Behavior
A busy shoaler that uses the middle and upper water. It is peaceful in a proper group, but in small numbers it can turn nippy. That makes it a poor match for bettas, fancy guppies and angelfish. Other tetras, rasboras, corydoras, small plecos and dwarf cichlids make good companions.
Breeding
Females are rounder and a little larger than males. This is a very productive egg scatterer; one female can lay hundreds of eggs. Use a separate tank with a mesh bottom or spawning mops, slightly soft and acidic water, and raise the temperature a couple of degrees. Remove the adults after spawning, as they eat the eggs, which hatch in about a day.
Tips from experienced keepers
- A group of ten or more keeps their nipping aimed at each other instead of your other fish.
- The head-up swimming angle is normal for this fish, not a sign of illness.
- Keep a lid on the tank, since penguin tetras may jump when startled.
- Most fish sold as penguin tetras are Thayeria boehlkei, also called the false penguin tetra.
Frequently asked questions
Are penguin tetras fin nippers?
They can be, mainly when kept in small groups. In a shoal of ten or more nipping is rare, but avoid long-finned tank mates to be safe.
How big do penguin tetras get?
Most reach about 2 in (5 cm) long in aquariums, counting the tail. Females are slightly larger and fuller than males.
Can penguin tetras live with shrimp?
Adult dwarf shrimp are usually left alone, but baby shrimp will be eaten. Thick plants or moss give young shrimp a place to hide.
Sources
We checked these references when writing this page. Values are for healthy long-term keeping, not survival limits. Last reviewed 2026-10-13. See our editorial policy.