Serpae tetra care guide
Also called: Jewel tetra, Red minor tetra, Callistus tetra, Red serpae tetra
The serpae tetra is a hardy, bright red tetra with a black shoulder spot. It is also one of the worst fin nippers among tetras, so keep a group of 10 or more and choose fast, short-finned tank mates.
Serpae tetras need a tank of at least 20 gallons (76 L), a group of 10 or more, and water at 22–26°C (72–79°F) with a pH of 5.5–7.5. They grow to about 4.5 cm (1.8 in) and are semi-aggressive.
Plan a tank with serpae tetrasSee all tank mates
Serpae tetra quick facts
| Scientific name | Megalamphodus eques |
|---|---|
| Family | Acestrorhamphidae |
| Origin | Amazon and Paraguay river basins, South America (most are farm-bred) |
| Adult size | 4.5 cm (1.8 in) |
| Minimum tank | 20 gallons (76 L), at least 75 cm (30 in) long |
| Temperature | 22–26°C (72–79°F) |
| pH | 5.5–7.5 |
| Hardness (GH) | 2–15 dGH |
| Group size | 10 or more (shoaling fish) |
| Temperament | Semi-aggressive |
| Swims at | Middle |
| Diet | Omnivore |
| Care level | Easy |
| Lifespan | 4–7 years |
| Safe with shrimp? | No, eats shrimp |
| Safe with plants? | Yes |
- Notorious fin nipper: avoid long-finned tank mates.
Tank setup
A group of 10 needs at least a 20-gallon (76 L) tank about 30 in (75 cm) long. Bigger groups do better in 29 gallons (110 L) or more. Put plants and driftwood along the back and sides and leave open water in the middle. Extra space and cover cut down on chasing.
How many serpae tetras in a tank?
The smallest common tank that suits serpae tetras is a 20 gallon long. 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 | Serpae tetras (alone) |
|---|---|
| 3 gallon | Too small |
| 5 gallon | Too small |
| 10 gallon | Too small |
| 15 gallon | Too small |
| 20 gallon | Too small |
| 20 gallon long | 10–22 |
| 29 gallon | 10–33 |
| 40 gallon | 10–45 |
| 55 gallon | 10–62 |
| 75 gallon | 10–85 |
| 125 gallon | 10–142 |
What you need for serpae tetras
Sized for a 20 gallon long tank, the smallest common size that suits a group of 10 serpae 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 long 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, 50 W (opens Amazon in a new tab)Holds about 75 °F (24 °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 45 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 30 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 serpae tetras
- Micro pellets or flakes for small fish (opens Amazon in a new tab)Small enough for tetras, rasboras and other nano fish.
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Water parameters
Aim for 72–79°F (22–26°C), a pH of 5.5–7.5 and soft to moderately hard water. Farm-bred fish adapt well to most tap water. Their red color is strongest in a planted tank with clean, stable water.
Best tank mates for serpae tetras
These popular species share serpae tetras' water needs and temperament. See the full list of 36 good matches.
Nerite snail
2.5 cm (1 in) · 22–27°C (72–81°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)
Tiger barb
7 cm (2.8 in) · 22–27°C (72–81°F)
Assassin snail
2.5 cm (1 in) · 22–27°C (72–81°F)
Ramshorn snail
2 cm (0.8 in) · 21–27°C (70–81°F)
Malaysian trumpet snail
2.5 cm (1 in) · 20–27°C (68–81°F)
Mystery snail
5 cm (2 in) · 21–26°C (70–79°F)
Avoid keeping serpae tetras with
- Angelfish: Serpae tetra is a well-known fin nipper and will shred the long fins of angelfish.
- Betta fish: Serpae tetra is a well-known fin nipper and will shred the long fins of bettas.
- Cherry shrimp: Serpae tetra eats small shrimp like cherry shrimp.
- Dwarf gourami: Serpae tetra is a well-known fin nipper and will shred the long fins of dwarf gouramis.
- Fancy goldfish: Serpae tetra is a well-known fin nipper and will shred the long fins of fancy goldfish.
- Guppy: Serpae tetra is a well-known fin nipper and will shred the long fins of guppies.
Feeding
Serpaes are greedy omnivores. Use a good flake or small pellet as the staple and add frozen or live bloodworms, daphnia and brine shrimp a few times a week. Spread food across the surface so the whole group can eat, since crowding at feeding time can set off fin biting.
Behavior
This fish is well known for nipping fins, and it gets worse in small groups or cramped tanks. A group of 10–12 or more keeps most of the squabbling inside the school. Never keep them with bettas, angelfish, gouramis, fancy guppies or other slow, long-finned fish. Fast fish such as zebra danios, black skirt tetras and corydoras make better tank mates.
Breeding
They scatter eggs and give no parental care, and a few fry sometimes appear in planted tanks. For more fry, use a dim breeding tank with mesh, marbles or a spawning mop on the bottom and soft, slightly warm water. Remove the adults once eggs appear. Start the fry on infusoria, then move to baby brine shrimp.
Tips from experienced keepers
- Keep at least 10. In small groups they turn their nipping on other fish.
- Never house them with bettas, angelfish, gouramis or fancy guppies.
- Scatter food so the whole group eats at once. Crowding at the food is when fin biting often starts.
- Check new tank mates for torn fins during the first weeks, and have a plan to separate them if needed.
- Don't trust them with cherry shrimp or other dwarf shrimp. They may go after adults as well as babies.
Frequently asked questions
Are serpae tetras fin nippers?
Yes. They are among the nippiest tetras in the hobby. A large group, a roomy tank and fast, short-finned tank mates keep the problem under control.
How many serpae tetras should be kept together?
Keep at least 10, and 12 or more is even better. In bigger groups they spend their energy sparring with each other rather than harassing other fish.
Can serpae tetras live with bettas?
No. Serpaes are very likely to shred a betta's long fins. Pick tank mates that are quick and have short fins.
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.