The Lake Burley Griffin Red Shrimp - Myth Or Undiscovered Native? By Mark O'Connor

 

Actually, if it exists it is unlikely to be peculiar to Lake Burley Griffin, though that is the only place I have yet seen it. What is certain is that the weed beds and willow roots of most Australian lakes contain myriads of glassily beautiful atyid shrimps. Like glassfish, these aren't easily seen until you put them in a tank. But if you pass a net through the weeds you will usually catch two or three per sweep. They get up to about 6 cm long, although most are smaller.

 

Some people use them as live food, but they will settle happily and inoffensively into a tank with smaller fish, eg neons or live bearers, and soon become quite bold. After all they survive in nature among the notorious fin-ripping gambusia fish. I find them beautiful - they are also diligent scavengers and will spend hours rolling up strands of algae with their many appendages and disposing of it. So far as I can check, they tolerate tropical temperatures indefinitely.

 

One word of caution. The permanent waters they live in always contain fish and therefore fish parasites. It is said that most fish parasites can only survive two or three days at tropical temperatures without a finned host. But even if the shrimp are kept for a few days or are well "washed" in new water before going into your tank, there is a further risk that they might harbour some internal parasitic worms (such is known from other parts of the world) whose life-history involves a stage inside the shrimp and a stage inside the fish. I gather though, that such infestations are rarely serious and that they soon die out if fish and shrimp are re-separated. Still, you might prefer to quarantine the shrimp for a longer period.

 

Freshwater aquarists are accused of neglecting invertebrates, but the problem is many of them are too quickly eliminated by fish or else (like crayfish) are a danger to the fish. The shrimp is neither. Unlike the freshwater prawns sometimes found with them, the shrimp have no claws. The worst they might do is eat fish eggs - which makes little difference in a community tank.

 

For a display tank, they are inconspicuous, unless kept with small fish that require close up observation. Even then, the delicate details of their many appendages is not too easily seen. What we really need to make them a roaring success in aquaria is a coloured shrimp - that would really stand out.

 

And I have seen one - in fact half a dozen - over several years when I used to occasionally collect shrimp from the lake. These were bright red, though I also saw some that were patchily red, and a few that had strong hints of other colours (Some may have been due to algae or other growths on the skin). I even once had a pair (or at least a couple) of bright red ones at the same time. However I had to leave them in the care of an acquaintance while I was away for a summer - with fatal results.

 

Apart from their colour, the red shrimp were identical with the others, so most likely we are talking about a rare recessive mutation. If so, then such individuals would have to be "pre blooded" and a pair of them would breed true. Something similar happened with the spectacular blue marron crawfish in Western Australia. It was a natural mutation which was "fixed" for aquarium use, though in this case the gene was not entirely recessive. I imagine that females carry the eggs on their undersides, so it should be possible to see when they are "in berry" and take extra care to preserve the young.

 

The red mutants are extremely rare. Those who collect the shrimp usually fish "blind", just pushing the net through any likely patch of weeds or willow roots (eg along the sides of Commonwealth Park or near the old Canberra Hospital site). One CDAS member believes they may be more common in Lake Ginninderra. Chances of spotting the coloured ones are much higher if you go wading with the net (in waders or gumboots - except in high summer!) Once or twice on a glassy day on the protected shore of the lake I was able, with the sun behind me, to glimpse thousands (if not millions) of shrimp scudding away over a shallow weed bed as the net disturbed them. Under these conditions the coloured ones stood out clearly and could be pursued. Most of my catches came under these conditions.

 

I no longer frequent the lake, but I would still be very interested to try a captive breeding program if I could get four or five pure red individuals. If anyone is regularly netting them, I would greatly appreciate them saving any coloured ones they come across (my phone number is 62473341). Or they might be interested to try and breed them themselves. I would also be interested to hear if anyone has any experience of breeding freshwater shrimp.