Dwarf neon rainbowfish care guide
Also called: Neon dwarf rainbowfish, Praecox rainbowfish, Neon rainbowfish
The dwarf neon rainbowfish is a small, lively rainbowfish with a shiny blue body and red fins on the males. Keep six or more in a 20-gallon long (76 L) or bigger tank with open swimming space.
Dwarf neon rainbowfish need a tank of at least 20 gallons (76 L), a group of 6 or more, and water at 23–27°C (73–81°F) with a pH of 6.8–7.5. They grow to about 6 cm (2.4 in) and are peaceful.
Plan a tank with dwarf neon rainbowfishSee all tank mates
Dwarf neon rainbowfish quick facts
| Scientific name | Melanotaenia praecox |
|---|---|
| Family | Melanotaeniidae |
| Origin | Mamberamo River system, northern New Guinea (Papua, Indonesia); aquarium fish are mostly captive-bred |
| Adult size | 6 cm (2.4 in) |
| Minimum tank | 20 gallons (76 L), at least 76 cm (30 in) long |
| Temperature | 23–27°C (73–81°F) |
| pH | 6.8–7.5 |
| Hardness (GH) | 5–15 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? | No, eats shrimp |
| Safe with plants? | Yes |
- Known jumper: keep a tight-fitting lid.
Tank setup
A group of six needs at least a 20-gallon long tank (76 L, 30 in / 76 cm long), and a 29-gallon gives more room. They are fast swimmers, so leave open water in front and put plants along the back and sides. Taller plants break up sight lines between males. Use a tight lid.
How many dwarf neon rainbowfish in a tank?
The smallest common tank that suits dwarf neon rainbowfish 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 | Dwarf neon rainbowfish (alone) |
|---|---|
| 3 gallon | Too small |
| 5 gallon | Too small |
| 10 gallon | Too small |
| 15 gallon | Too small |
| 20 gallon | Too small |
| 20 gallon long | 6–14 |
| 29 gallon | 6–21 |
| 40 gallon | 6–29 |
| 55 gallon | 6–40 |
| 75 gallon | 6–55 |
| 125 gallon | 6–92 |
What you need for dwarf neon rainbowfish
Sized for a 20 gallon long tank, the smallest common size that suits a group of 6 dwarf neon rainbowfish. 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, 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 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 dwarf neon rainbowfish
- Tropical fish pellets (opens Amazon in a new tab)A good staple for medium community fish.
- Tight-fitting lid for a 20 gallon tank (opens Amazon in a new tab)Dwarf neon rainbowfish can jump out of an open tank.
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Water parameters
Keep it at 23–27 °C (73–81 °F), pH 6.8–7.5 and 5–15 dGH. It prefers water on the harder side, so add crushed coral if your tap water is very soft. Regular water changes and steady conditions matter more than exact numbers.
Best tank mates for dwarf neon rainbowfish
These popular species share dwarf neon rainbowfish' water needs and temperament. See the full list of 95 good matches.
Betta fish
6.5 cm (2.6 in) · 24–28°C (75–82°F)
Nerite snail
2.5 cm (1 in) · 22–27°C (72–81°F)
Guppy
5 cm (2 in) · 22–27°C (72–81°F)
Dwarf gourami
7.5 cm (3 in) · 24–28°C (75–82°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)
Avoid keeping dwarf neon rainbowfish with
- Cherry shrimp: Dwarf neon rainbowfish eats small shrimp like cherry shrimp.
- Common goldfish: They need different temperatures: Dwarf neon rainbowfish 23–27°C (73–81°F), common goldfish 15–22°C (59–72°F).
- Oscar: Oscar can eat dwarf neon rainbowfish: 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 dwarf neon rainbowfish.
- Convict cichlid: Convict cichlid is aggressive and will bully or injure peaceful dwarf neon rainbowfish.
- Discus: They need different temperatures: Dwarf neon rainbowfish 23–27°C (73–81°F), discus 28–30°C (82–86°F).
Feeding
It is an eager omnivore. Feed small flakes or nano pellets as the base, plus frozen or live brine shrimp, daphnia, cyclops and bloodworms. Some live or frozen food each week keeps the males' red fins bright.
Behavior
It is peaceful and fits community tanks with similar-sized fish such as tetras, rasboras, corydoras, gouramis and other small rainbowfish. In small groups it is skittish, so keep six or more, with at least one or two females per male. Males spar and show off but rarely do harm. Adults can eat cherry shrimp and shrimplets; amano shrimp are usually left alone.
Breeding
Males are larger, deeper-bodied and brighter, with red fins; females are slimmer and paler. Well-fed fish spawn almost daily, scattering eggs on a floating spawning mop or fine plants. Move the eggs to a separate container, where they hatch in about 7–10 days. Feed the fry infusoria or very fine powdered food, then baby brine shrimp after a week or two.
Tips from experienced keepers
- Buy a mixed group with at least as many females as males to reduce chasing.
- Pick a tank at least 30 in (76 cm) long. These small fish still swim fast and far.
- Red fins fade on a dull diet, so offer live or frozen food a few times a week.
- Add crushed coral to the filter if your tap water is very soft.
Frequently asked questions
How big do dwarf neon rainbowfish get?
Most adults reach about 2.5 in (6 cm), and a few males grow to around 3 in (8 cm). Females stay a little smaller.
What size tank do dwarf neon rainbowfish need?
A group of six needs at least a 20-gallon long tank (76 L). A 29-gallon or larger tank is better for a bigger group.
Can dwarf neon rainbowfish live with shrimp?
Not reliably. Adults can eat cherry shrimp and their babies. Larger shrimp such as amano shrimp are usually safe.
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.