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February 22, 2013

For the last ¾ of a decade I have spent my time studying, observing, and pestering my boss about fish. When I tell people what I do for a living I am often met with the eager question of what got me into fish? Usually this is followed up with some sort of saltwater question and that’s when my “freshwater snob” side comes into play. If you like saltwater fish, than I am sorry if I offend you, but it’s just boring to me. Sure, it’s pretty to look at, but in my honest opinion, I like freshwater more. There’s something more appealing about a well planted aquarium with a school of 50 Cardinal Tetras making their way through the plants. Anyway I’m rambling again. Where was I? Oh yes, why I like freshwater fish? Well, I may not be much of a rainbow enthusiast, but these fish will certainly give you a good answer…

I believe it was around this time last year when I last wrote about the native fishes of Australia, New Papua, and New Zealand commonly known as Rainbowfish. I think it’s time we revisited these fish as there has been some species updates, and many of you enjoy the fish. I, for one, like them a lot, but will most likely never be one of those folks who keeps them at home. My love for South American cichlids is too strong and tank space is too few at home.

To begin I should cover what the native homes for Rainbowfish can be like. Often the rivers and lakes are rocky areas with some downed branch wood hanging over the banks. The water column is usually a murky tea color. In Indonesia the locals call these blackwater biotopes “kali kopi”, or “coffee stream”, for the dark colors. The pH can vary considerably from 3.9 all the way to 9.4. We have found that keeping the fish in a neutral pH seems to keep them thriving and happy in an aquarium. I also highly advise offering a variety of foods such as flakes and live foods. We’ve found that baby brine works the best for most them. Rainbowfish would make great additions to community tanks, and they are usually peaceful (aside from disputes for rank among the males). The fish are often brightly colored, and if you really want to see how they act in nature than it’s best to keep them in small groups of their same species as they are a schooling fish. This can be accomplished by keeping 6 or more individuals in an appropriate size aquarium.

In this article I will be covering the genus Pseudomugil and a few of its described species. The group is more commonly known as the Blue Eye Rainbow fish, and these elegant fish usually do not grow larger than 3.5”. You can identify Blue Eye Rainbows by a slender body, two dorsal fins that are separated in the middle, and, of course, the bright blue eye. Blue Eyes were originally in the genus ‘Popondetta’, but this was already being used by another family and was then changed to Popondichthys in the late 80’s. In 1989 a revision would occur and all of the members were changed to the current genus. I am almost certain many of you are familiar with one of the most common, Pseudomugil furcatus “Forktail Blue Eye Rainbow- therefore I will be leaving this one out for the topic.

The first species described was Pseudomugil signifer “Pacficic Blue Eye Rainbow” in 1860. Over the years various name changes had occurred, and eventually the northern (P. signatus) and southern (P. signifer) were separated. Later on the two would be back into the species we know them as today. In 1979, researchers used electrophoretic research from 14 different localities to determine if there were differences among the Pacific Blue Eye Rainbow because there were so many morphological variations. Though there work showed the species was equivalent to each other, today studies show that there is good reason to reconsider them as actually two different fish along the eastern shoreline of Australia. Breeding experiments have demonstrated that interbreeding will not occur between species from the north and south. This suggests that further work should be done to determine if these are indeed two different species or not. Whatever the outcome, the Pacific Blue Eye Rainbow is a highly attractive fish that is typically transparent in the front half of the body. The rear half is an orange hue that extends into the anal and second dorsal. These fins form an incredibly sharp point, and the caudal fin is etched in white. When the males are displaying for one another it’s a sight that would make you want to bring home a group.

Pseudomugil signifer

Pseudomugil signifer female


One of the smaller members, Pseudomugil gertrudae “Gertrude’s Rainbow”, is endemic through Australia and New Guinea. There is several color forms that can be found throughout each region and each may have longer fins, fewer spots, larger spots, and even the adult size of the fish may be different. Habitually, the body is silver to blue or even gold in some locales in color that exhibit several black spots along the fish and fins. The caudal fins are brightly colored yellow and the tips of the pectoral fins are etched in white. The habitat is so greatly variable that the pH can range from 3.9 all the way up to 8.2 in some areas. This all depends if the fish came from “blackwater” or not. If my studies are right than the specimens we import originally came from Goanna Lagoon and would be considered a blackwater fish, but seems how these are tank raised they do not need such a low pH to thrive and be successful in your aquarium.

Pseudomugil gertrudae

Pseudomugil gertrudae

P. gertrudae is very similar to Pseudomugil cf. paskai “Irian Red Neon Rainbow”, with the only differences appearing to be the size and shape of the fins. The Irian Red Neon Rainbow, at first, was imported in as “Irian Red Neon” or simply “Red Neon”,and thought to be a hybrid of P. gertrudae, but the fish appears to be found in the Irian mountians of New Guinea. Today they are known as a color form of P. paskai by sharing similarities to this fish, instead of the Gertrudae Rainbow. Male Irian Red Neon Rainbows are an intense red color with a blue sheen. Like the other members of the genus the pectoral and ventral fins are extremely erect and have white tips on the end of them. Much like gertrudae their body is covered with brilliant dark spots on the body and fins. There seems to be little info regarding the full grown size, but my estimation would be somewhere around 1.5".

Pseudomugil cf. paskai

Pseudomugil cf. paskai

In the Timika region of West Papua a newly described rainbow can be found in shallow and narrow streams. The water is generally clear with sparse vegetation; this makes Pseudomugil ivantsoffi “Ivantsoff’s Rainbow” easy to spot along the shoreline. Oginially the fish was identified as P. reticulatus, but after close studies it was revealed that the two are indeed distinctive species. Ivantsoff’s Rainbow is probably my favorite within the genus. The body color is a green to yellow, and the dorsals, anal, and ventral fins are an incredible fiery yellow. The caudal fin is a dark red that is etched in white like P. signifer. This is another small species that grows to around 1.5” or so. I would highly recommend trying to keep them in a planted tank!

Pseudomugil ivantsoffi

Pseudomugil ivantsoffi

I think I’ve exhausted my fingers enough for one day. I hope you have enjoyed reading my newsletter this week just as much as I have enjoyed educating myself a little further on rainbows. If you would like to know more about these or any of our other fish, please feel free to call or email me.

Happy fishes!

Anthony Perry
Sales Manager