Welcome home mudfish!

There was quite a party last Friday when nationally threatened black mudfish were returned to their new home near the Waikato Expressway – Gordonton ecologist David Riddell had a part to play in the action.

"There you go little fellas...:  David and Kessels colleague Alicia Catlin release the mudfish.
“There you go little fellas…:” David Riddell and Kessels Ecology colleague Alicia Catlin release the mudfish.

Five year’s previously he discovered the rare native creatures while carrying out a preliminary ecological survey before work began on the expressway section from Rangiriri to Te Kauwhata.

“I saw some juvenile fish swimming around in a small, weedy drain above a broken culvert. They were in a very small area, and unfortunately it was right in the path of the new expressway.”

The presence of a large population was confirmed by setting nets and traps and last June David, with fellow Kessels Ecology ecologists Dr Jennifer Price and Gerry Kessels, rescued many of the fish.

They were transferred to Waikato University, where one of New Zealand’s foremost mudfish experts, Dr Nick Ling, looked after them in a series of concrete water troughs planted with native wetland vegetation.

Meanwhile, at the expressway site, work was underway constructing new wetland areas adjacent to their lost habitat.

Students from Rangiriri School, local tangata whenua and other invited guests joined representative from the NZ Transport Agency, Fletchers Construction and Kessels Ecology to welcome the little guys home on Friday.

Freedom!  (Soon, just sit still for a moment while the kids admire you.)
Freedom! (Soon, just sit still for a moment while the kids admire you.)

Their new habitat, built by Fletchers, includes a winding channel, surrounded by shallower wetland areas planted with native plants. It is more than double the size of their original area and has been designed to exclude predators such as eels.

Dr Jennifer Price from Kessels told the assembled guests that mudfish are distant relatives of whitebait and are nocturnal. They are unique to New Zealand and survive in places where the water dries up in summer, by burrowing down into the mud and waiting for the water to return.

“They are an important part of our indigenous biodiversity – just like kiwis but not quite as cuddly.”


Children from Te Kura o Rangiriri get up close... Photos: Stephen Barker
Children from Te Kura o Rangiriri get up close…


These kiwis seem to think mudfish are cuddly...
These kiwis seem to think mudfish are cuddly… Photos: Stephen Barker


For a previous story on the capture of the little critters on Number 8 Network, click here.

Gerry Kessels, left, and David setting the traps last June.
Gerry Kessels, left, and David setting the traps last June.



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6 thoughts on “Welcome home mudfish!

  • September 9, 2014 at 5:12 pm

    To David and others.

    I have reason to believe they are more common, in our local drains than we think. We just don’t study them long enough, and hard enough, looking for movement.

    It was 50 years before I became aware, one dry autumn, that the bubbles arising from what remained of the water in our Taupiri Drainage Board maintained drain [between my immediate neighbours] were being created by very small fish splashing in the shallows and mud, than the swamp gas I assumed was rising. I was walking along the water logged drain shoulder and that was creating noticeable vibrations, and then clusters of surface bubbles / splashes. The water was so turbid and stale looking, it appeared to have an oily slick to it, so I was very surprised, that hot day, to see fish. Only a small spring 160 m away kept the drain from drying out completely.

    I can remember the swampy valley floor with it’s original hand dug drain, that sometimes in the autumn dried out completely. Then next spring wading through it looking for pukeko and duck nests, and then Mr Morgan [?] the Maori man from Garfield street; Mr Dunlop; and Mr Web and co, forming it with a dragline excavator, and then maintaining it every few years. Boy how we chased the eels, but I never remembered seeing the little fish, though there was one possibly 50 cm long which we rescued from the top of the farm drain by Smith’s, and put in Lovegrove’s cowshed water trough along with their gold fish. Needles to say it did not last. That was probably in the late 1950’s, yet it was the 1990’s before I spotted any fish swimming.

    Alan SHARP.

    • September 10, 2014 at 8:37 am

      Alan I think you’re right about them being more widespread than we know. I’ve now seen mudfish in a number of places from Whangamarino to Piopio, in most cases picking them up from their juveniles, which swim in open water by day during winter and early spring. On the other hand there are plenty of places I’ve looked for them and not seen them!

      Given that you saw them in the autumn and juvenile mudfish are only visible by day in winter and early spring, I suspect the fish you saw in the Taupiri Drainage Board drain would have been mosquitofish. They were introduced in the 1930s to control mosquitoes, something they really don’t do at all well. They’re a major threat to freshwater invertebrates and native fish, including mudfish – another badly thought-out introduction.

      The little fish you mention – did you mean 50 mm rather than 50 cm? If so that could well have been a mudfish, because the habitat sounds suitable. On the other hand it could have been a big female mosquitofish – basically mudfish look like stumpy little eels, while mosquitofish are more like typical fish, very similar to guppies only not as colourful. Can you remember what your fish looked like?


      • September 14, 2014 at 1:29 pm

        Greetings again David.

        Yes to the 50mm = 2″ found in the head of the drain, mainly mud, with little obvious flowing water, at that time, in the 1950’s. Looked fishy enough for me to consider it was not a little eel, so we put it with Lovegrove’s gold fish.

        Re the little fish I have seen; any time you have an hour to spare, you only have to travel 2 Km from your home, to Andrew Gurnells drain. Between Andrew’s culvert and SH1A. I have not found them further up, closer to the little spring halfway up the Larsen / Kay boundary. With a little patience, you can find them swimming in little schools during the day. First indication is the little bubbles / splashes, as they swim in the shallow water on top of the mud, through the over hanging grasses. They get concentrated in the droughts, because there is so little water left. Water I would have thought fish could not survive in, because of the heat, UV light, and associated lack of oxygen. They are very small fish.

        They don’t take to bread bait, nor did it appear some raw meat, and I was never quite quick enough to catch any in a suspended jar, by one of the culverts in that drain. The water looks very shallow, but I know the mud to be over a meter deep, so weary of falling in. You on the other hand would have catching nets, allowing a closer look. I assumed the dragline cleans, would have cleaned them out, but they remain after each clean. They were there, less than a year ago, when I called upon Andrew.

        Alan SHARP.

        • September 15, 2014 at 8:20 am

          Hi Alan, definitely sounds like mosquitofish. They’re amazingly tough, and can survive very low oxygen levels and very high temperatures. They can even survive salt water for a short time – I’ve seen them around the edge of the Manukau Harbour in the mouths of little creeks, and they’ve spread themselves all around the streams flowing into the harbour that way. About the only thing they can’t tolerate is the water drying up completely, which is the one thing that gives mudfish an edge! More info here: http://www.doc.govt.nz/conservation/threats-and-impacts/animal-pests/animal-pests-a-z/fish/gambusia/


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