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Joe Kaznica
Title: Gertrude's Rainbow, Pseudomugil gertrudae
Summary:  Also known as the spotted blue-eye, this is a "continuous spawner" that lays one to three eggs per day on mops placed on the bottom of the tank.
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Date first published:  2001
Publication: Gravel Gossip, Diamond State Aquarium Society.
Reprinted from Aquarticles:
February 2004: Posted by Andrew Collins on his UK site
May 2004: Fins & Friends, Regina Aquarium Society
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Gertrude's Rainbow
Pseudomugil gertrudae

by Joe Kaznica
First published in Gravel Gossip, Diamond State Aquarium Society

Gertrude's Rainbow is a very small rainbow fish that is found in northern Australia and New Guinea. It comes from streams in five very localized areas and is not wide spread. It is part of fifteen species that make up the "blue-eye" family. When you see the fish, you will instantly know why it is a "blue-eye." Even as small fry, this fish has bright fluorescent blue eyes. The males are an overall green yellow in color with bright yellow wing like pectoral fins. The dorsal and pelvic fins are very feather like. The female has shorter fins, but is very attractive by having an overall blush of orange, which is deeper at the tail. Both males and female are covered with spots. This species is also known as the Spotted Blue-eye. The adult fish is only a little more than an inch in length and is perfect for a small 2.5-gallon or 5.5-gallon aquarium. It can be kept in a community set up, but the inhabitants must all be very peaceful. It likes to be warm, about 80 degrees at neutral pH. It was first described by Weber in 1911, but was only introduced to the international aquarium hobby in the 1982 to 1985 time frame.

P. gertrudae is a very easy and interesting fish to spawn. It is what I call a "continuous spawner."  I set up three males and six females in a ten-gallon tank at 80 degrees, pH of 7. I place gravel in the tank, just enough to cover the bottom. I add two green spawning mops. My spawning mops are made of nylon yarn. Each mop is made of about 25 strands of yarn, which are about thirty inches long. The mop is then folded in the middle so that you achieve a fifty-strand mop that is about fifteen inches long. I have seen spawning mops of many different colors, but green seems to work the best for me. An important point with P. gertrudae is not to suspend the mops in the tank, but let them sink to the bottom. This species is a bottom spawner, and greatly prefers the spawing mops on the bottom. The males will display for the females as day light increases. Most spawning takes place about mid morning and is very gentle. The females lay one to three eggs per day onto the mops. After about a week, I take the mops from the tank and remove the eggs by hand into a one-gallon tank. The three females will give me about thirty eggs per week. I place some plants into the fry tank to get some microorganisms growing to be available as food once the eggs hatch. This is where you have to be patient as it takes about twenty days for the eggs to hatch at 78 degrees. Once I see fry free swimming, I add 'Liquid-Fry' food and baby brine shrimp about twice a day into the fry tank. Growth is quite rapid, and you will have an adult fish in about three months. If you keep this species by itself, you will find babies in the tank, as the adults do not appear to prey on their eggs or fry. However, you will only get a few fish this way. My own experience is that this species is not a very long lived and they should be considered annuals.