Pseudomugil gertrudae ‘Giddy River’
Weber 1911

Common Name: Spotted Blue-eye or Gertrude’s Blue-eye

Family: Pseudomugilidae (Blue eyes)

P. gertrudae was named for the wife of Dr. Hugo Merton (Gertrude Merton), a scientist who visited the Aru Islands.   Pseudomugil means false mullet.

The fish were first collected in the early 1900’s by Dutch collectors in the Aru Islands.

Pseudomugil gertrudae is found in northern Australia, southern New Guinea and the Aru Islands. There are many different populations of this species. They have been collected in New Guinea from Pahoturi, lower Fly, and the Bensbach river systems. There are at least 5 populations known just from Australia. These populations are fairly scattered. They include: northern Cape York, the Murray Swamps (QLD.), Finniss River system (near Darwin), Melville Island, and eastern Arnhem Land, NT. The latter is where my fish comes from originally.

Map - Giddy RiverThe body of these fish is a basic silvery grey colour. The scales seem to be outlined lightly in black. Eyes are blue, of course. Pectoral fins can be variable in colour since there are so many locales of gertrudae. They can range from yellow to orange to an almost red colour. Many of the fins are tinged on the edge with white. The dorsal, anal and caudal fins can be white or yellow. These fins are covered in dark spots.

Males have elongated dorsal, anal and pelvic fins. They also have more spots than females. Variable fin shapes are possible due to the many different locales.

These are a delicate looking fish that reach a maximum of about 3.8 cm (approx. 1 ½”). They eat mainly insects, insect larvae and crustaceans as their main diet in their natural habitat.

In the wild, spawning usually occurs between October and December. Males display to females and chase them. The display usually consists of the male raising up his dorsal fins and spreading the anal fin. Each female will lay approximately 10-12 eggs during the day. Eggs are clear and are quite large for such a small fish.

These eggs generally hatch in 9 to 11 days depending on conditions.

Pseudomugil gertrudae prefers to live in small creeks, lagoons, billabongs, swampy marshes, and rainforest streams. They also like backwaters next to major rivers.  It likes these areas to but gertrudae are usually found in fairly soft waters with a temperature range of 23 to 30° Celsius (73-86°F), and pH 5.2 to 7.6.

P. gertrudae - Giddy RiverWe received a shipment of fish and eggs from a fellow ANGFA-NA member (Kevin Hosmer). The live fish was a surprise since we had requested eggs. It was a wonderful surprise though!

It turned out to be a lucky surprise as only one of the eggs actually hatched and survived for us. I placed the small group of 10 fish into a 20 gallon tank. The tank has floating hornwort and a spawning mop in it. I have the tank at room temperature since there is no heater in this tank. The group consisted of a few adults and some juveniles. I was really impressed by the pretty little males. The pectoral fins are a nice orange colour and the other fins were a delicate yellow (some with spots of course!). This tank gets fed a supply of live baby brine shrimp and flake. I added a small amount of salt to this tank as they prefer some salinity to their water.

I started checking the mops a few weeks after I received the fish and since I had a group, I had what I considered decent numbers of eggs every day. I collected approximately 40 eggs over a couple of days. I removed the eggs from the mop and placed them into a small clear corningware baking dish on top of a tank that has a strong lid on it. I used the water from the parents tank for this. I placed a small airstone in the container to keep the water moving slightly. From what I can tell, it appears that all the eggs hatched. In about 10 days or so, they started hatching. The first week we fed the fry exclusively microworms. After that they still got microworms in the morning but started getting some feedings of baby brine shrimp in the evenings. They grew well on this diet and have now been placed back into the parents tank. I grew these fry out separately for breeders points, but it appears that I didn’t have to do this as many fry have appeared in the parents tank. It looks as if the adults don’t eat their fry if they are well fed.

 © Copyright 2004 Lisa Boorman
All Rights Reserved

Suggested Reading:

Baensch Aquarium Atlas by Dr. Rüdiger Riehl & Hans A. Baensch

Rainbowfishes In Nature and in the Aquarium by Dr. Gerald R. Allen

Australian freshwater fishes : biology and management by John R. Merrick
 Aqualog Special: Breathtaking Rainbows by Harro Hieronimus                                               

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