Max Size: 2.5cm

Spotted Blue Eye Rainbowfish (Pseudomugil gertrudae)

The awesome Spotted Blue Eye Rainbowfish, Pseudomugil gertrudae, is a small stunning, peaceful and timid species and must be kept in groups, or they will become skittish and feel intimidated by other residents of their aquarium.

They are not ideal for the community tank as they may be outcompeted for food and are therefore bust kept alone or alongside other fishes of comparable size, requirements and disposition. However, you should avoid maintaining this little gem with other Pseudomugil species, such as the Red Neon Blue Eye Rainbowfish if you intend to breed them as they can hybridise.

The Spotted Blue Eye Rainbowfish have a compressed and elongated body that is a semi-transparent blueish-silver colour, occasionally having an overall gleam of golden-yellow. The swim bladder is visible, along with two close-together dorsal fins. There is a significant difference in size between the first and second fins.

The tips of the pectoral fins are usually bright yellow, orange or orangey-red, and the other fins are often bordered with white. The anal, dorsal, and tail fins can be transparent to white, silvery-grey or yellow with oblong or rounded dark spots spread all over.

Several rows of body scales are bordered in black, displaying a charming latticework pattern over the body. All scales except those of the mid-ventral and mid-dorsal rows have a spot ranging in size and intensity, forming about six rows of irregular lines, except for the mid-lateral stripe, which seems to be continuous from just below and in line with the start of the first dorsal fin to the caudal peduncle.

There is considerable variation between these species in colouration, body size, finnage size, and shape.


Spotted Blue-Eye Rainbowfish
Spotted Blue-Eye Rainbowfish
Spotted Blue-Eye Rainbowfish
Spotted Blue-Eye Rainbowfish
Spotted Blue-Eye Rainbowfish
Spotted Blue-Eye Rainbowfish
Spotted Blue Eye Rainbowfish
Spotted Blue Eye Rainbowfish
Quick Facts
Scientific NamePseudomugil gertrudae
Other NamesSpotted blue-eye
OriginsAustralia, Papua New Guinea
Aquarium LevelMiddle
DifficultyBeginner - Intermediate
Best kept asGroups 5+
Lifespan3 - 5 years
Water Parameters
Water TypeFreshwater
PH4.5 - 7.5
GH5 - 12
TDS90 - 215
73 - 86℉
22 - 30℃


In the home aquarium, the Spotted 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.

Tank Mates

2 interesting tank mate ideas for the Spotted Blue Eye Rainbowfish could include:

Coral Red Pencilfish(Nannostomus mortenthaleri)
Staeck Endler(Poecilia wingei)

Sexual Dimorphism

It is relatively easy to determine the males from the females. Females commonly have a more profound body than the males whilst the adult males have larger dorsal, pelvic and anal fins, with extended filaments on the first dorsal and pelvic fins. The males also present more intense colour and spots on the fins and body.


Breeding the Spotted 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: 18/09/2020 - Updated: 12/08/2022 15:07:12