Pacific blue-eye (neon)
Pseudomugil cyanodorsalis
Also known as Neon blue-eye, Blueback blue-eye
Care at a glance
- Temperature
- 72–82°F (22–28°C)
- pH
- 7.0–8.5
- Adult size
- 1.4 in (3.5 cm)
- Minimum tank
- 12 gal (45 L)
- Temperament
- Peaceful
- Social behavior
- Schooling
- Swim level
- Middle
- Difficulty
- Medium
- Breeding
- Medium
- Rarity
- Common
- Origin
- Coastal northern Australia (WA, NT, Queensland), possibly southern New Guinea
- Family
- Pseudomugilidae
Overview
Keep them in a colony of 8 to 10 or more, in a tank of 45 liters or up, since the males show their best color when competing for attention. They are peaceful but timid middle swimmers that get outcompeted easily, so skip the general community tank and pair them only with small, gentle, salt-tolerant species. Hold the water warm, about 22 to 28 C, brackish, and at a pH of 7 to 8.5, on a tank that is already established. Feed small live or frozen foods like daphnia, moina, baby brine, and microworm. They are strong jumpers, so a tight cover is a must.
In the wild
Pacific blue-eyes come from coastal northern Australia, in tidal creeks and mangrove edges across Western Australia, the Northern Territory, and Queensland, and possibly southern New Guinea. These are warm, salty backwaters where fresh and sea water meet. To match that, give them a mature, well-planted tank of 45 liters or more with steady flow, good oxygenation, and brackish water, roughly 1 teaspoon of marine salt per 10 liters. Keep them warm, around 22 to 28 C, with a pH from 7 to 8.5.
Good to know
This is a tiny rainbowfish in the family Pseudomugilidae, topping out around 3.5 cm. It is euryhaline, meaning it handles a wide range of salinity, from about 25 to 50 percent seawater down to pure fresh in wild-collected fish. It is an egg scatterer with no parental care, and breeders raise eggs on spawning mops in a dedicated tank.
Did you know
Opinions split on whether they actually need salt. Wild fish live in brackish water and color up best there, but stock collected from the wild can adapt to pure freshwater and even breed in it. Either way, give them a mature, stable tank, since a fresh setup is the fastest way to lose such a small fish.
Where to buy
Some links may not be the exact species or variety.
- Imperial Tropicals Freshwater fish and inverts bred at a Florida hatchery
- The Wet Spot Tropical Fish Large freshwater selection from a longtime Portland fish store
…or ask your local fish store.
Appears in
Keeping Pacific blue-eye (neon)?
Track water tests, reminders and stocking fit.
Related species

Least killifish
Heterandria formosa1.4 in (3.5 cm)5 gal (20 L)68–79°F (20–26°C)
Endler's livebearer
Poecilia wingei1.6 in (4 cm)5 gal (20 L)72–86°F (22–30°C)
Melanzona Guppy
Poecilia parae2 in (5 cm)15 gal (55 L)75–82°F (24–28°C)
Cauca molly
Poecilia caucana2.4 in (6 cm)16 gal (60 L)77–86°F (25–30°C)
Guppy
Poecilia reticulata2.4 in (6 cm)13 gal (50 L)64–82°F (18–28°C)
Scarlet livebearer
Micropoecilia picta1.6 in (4 cm)16 gal (60 L)72–82°F (22–28°C)
