Max Size: 7cm

Pacific Blue Eye Rainbowfish (Pseudomugil signifer)

The Pacific Blue Eye Rainbowfish, Pseudomugil signifer is a peaceful, active and relatively hardy addition to any nano, planted or smaller species community aquarium. The males exhibit beautiful colouration and finnage, which is more pronounced during frequent and exciting sparring bouts that occur throughout the day.

Ideal tankmates for Pacific Blue Eye Rainbowfish could include other Pseudomugil Rainbowfish such as the Honey Blue Eye, Red Neon Blue Eye and Spotted Blue Eye Rainbowfish. However, it should be noted Pseudomugil species can hybridise, so if you aim to breed this fish and maintain its purity, other smaller Rainbowfish such as the Celebes Rainbowfish, Ornate Rainbowfish or Dwarf Neon Rainbowfish will make more suitable tank mates.

Other possible tankmates can include other peaceful species of similar size, disposition, and water requirements such as Peacock Gobies and Neocaridina Shrimp which can also make good tankmates; however it is worth bearing in mind small Shrimplets may fall prey to these fish.

Pacific Blue Eye Rainbowfish are a shoaling species; therefore, it would be better to keep them in a group of at least 8 to 10 individuals, preferably more. Maintaining these fish in such numbers will not only make them less nervous but will also result in a far more effective, natural-looking behaviour.

Males will also display some fascinating behaviour and show off their best colours as they compete for female attention.

You would preferably need to keep these Rainbowfish in a spacious aquarium as the males are somewhat intolerant of each other when they are in spawning condition.

Sometimes, the most dominant males can harass subdominants, who may fall victim to the stress if the aquarium is too small. Therefore, keeping them alongside other aquatic species is usually recommended to disperse aggression.

Pacific Blue Eye Rainbowfish have elongated partly transparent bodies and are pale yellow or olive with a silver operculum and stomach. Their scales are relatively large and are longer vertically than horizontally. Their eyes are large and they have a blue iris. These Rainbowfish have two dorsal fins; the first is typically in line with or just posterior to the longest pectoral-fin ray. In addition, they possess a forked tail fin with rounded tips, and the bottom and top edges of the tail fin are bordered with white.

The males usually have extended filaments on their dorsal, pelvic and anal fins. In addition, there are black markings on the base of the anterior rays of the anal and rear dorsal fins, the front is sometimes white, and the back edge is greyish. The male's fins may turn orange during the breeding season.

Pacific Blue Eye Rainbowfish (Pseudomugil signifer) Video

Pacific Blue Eye Rainbowfish (Pseudomugil signifer) Freshwater Aquarium Fish Profile & Care Guide


Pacific Blue Eye Rainbowfish
Pacific Blue Eye Rainbowfish
Pacific Blue Eye Rainbowfish
Pacific Blue Eye Rainbowfish
Pacific Blue Eye Rainbowfish
Pacific Blue Eye Rainbowfish
Pacific Blue Eye Rainbowfish
Pacific Blue Eye Rainbowfish
Pacific Blue Eye Rainbowfish
Pacific Blue Eye Rainbowfish
Quick Facts
Scientific NamePseudomugil signifer
Year Described1866
Other NamesNone
Aquarium LevelMiddle - Top
Best kept asGroups 8+
Lifespan2 - 3 years
Water Parameters
Water TypeFreshwater
PH6.5 - 7.5
GH5 - 15
TDS90 - 268
75 - 79℉
23.9 - 26.1℃

Natural Habitat

Merimbula Lake


In the home aquarium, the Pacific Blue Eye Rainbowfish will readily accept most good quality dried foods such as granules, flakes and sinking pellets. These modern food products have been developed to provide all adequate nutrition to maintain your fish's health and dietary requirements.

Providing additional foodstuffs such as live, frozen, and freeze-dried meals such as bloodworm, daphnia, and tubifex once or twice a week will provide additional benefits to your fish's health and well-being but is not a must for this fish.

It should be noted that bloodworms should only be given as an occasional treat and should not be used as the staple diet as they are difficult for fish to digest and can potentially cause blockages.

This fish is an omnivore in the wild, meaning it will consume some vegetable matter. Although most modern fish foods take this into account and include them in their products, you can still supplement your fish's diet with blanched vegetables such as spinach, broccoli, and zucchini. Ensure you do not overfeed your fish and remove any leftovers the following day.

Sexual Dimorphism

It is quite easy to differentiate between male and female Pacific Blue Eye Rainbowfish. Mature males are more brightly coloured and display longer finnage than females. The male is also a little larger and possesses black markings on their anal and dorsal fins.


Breeding the Pacific Blue Eye Rainbowfish is straightforward once these fish are happily established and settled into your aquarium. You will need a mature pair or group of males and females, along with a spawning mop, preferably floating at the top of the aquarium downwards to the substrate.

Despite spawning year-round, Rainbowfish lay many eggs at the beginning of the rainy season. In addition, temperature increases, and live and frozen foods often encourage spawning.

Check your spawning mops daily for any eggs that have been deposited and either remove the eggs from the mop or, better still, remove the entire mop to avoid contamination of the Rainbowfish eggs.

Tip: Have several spawning mops at hand so you can place a fresh spawning mop into the aquarium while you wait for the eggs to hatch on the other mop/s.

Place the spawning mop with eggs still attached into a separate small cycled aquarium with a sponge filter for flow, and add a few drops of Methylene Blue (Methylene Blue helps prevent fungal infections of eggs).

Your rainbowfish Eggs will hatch within 7 to 18 days, depending on the species and the temperature. We recommend 27°C = 80.6°F for the fastest development of fry.

Once the Rainbowfish fry hatch, they absorb their yolk sacs quickly and become free swimming, moving towards the water's surface. Once the fry reaches the water's surface, you can start feeding. We recommend feeding on Micorworm (the most straightforward live food to culture) and decapsulated brine shrimp egg powder several times a day while being careful not to overfeed and pollute the water column.

After a week or two, you can start to add newly hatched brine shrimp, but this isn't necessary to achieve a high success rate in our experience.

Rainbowfish fry grows slowly, so you should expect to wait several months before the fry is large enough to be added to the adult colony.

Other Rainbowfish of interest

Banded Rainbowfish(Melanotaenia trifasciata)
Boesemans Rainbowfish(Melanotaenia Boesemani)
Celebes Rainbowfish(Marosatherina ladigesi)
Dwarf Neon Rainbowfish(Melanotaenia praecox)
Forktail Blue Eye Rainbowfish(Pseudomugil furcatus)
Honey Blue Eye Rainbowfish(Pseudomugil Mellis)
View all Rainbowfish
Date Added: 05/08/2021 15:22:04 - Updated: 12/08/2022 12:57:22