A record-breaking little fish

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by Patrick Honan
Publish date
16 September 2016
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Common Jollytail (Galaxias maculatus) Common Jollytail (Galaxias maculatus)
Image: Patrick Honan
Source: Museum Victoria

Although Common Jollytails won’t break any records for fishing enthusiasts, they undoubtedly break the record for the most geographically widespread freshwater fish species in the world. Jollytails, also known as Galaxias, are unsung heroes of the fish world; featuring prominently in Melbourne Museum’s Forest Gallery, they are an ancient group, living in both fresh and salt water and yielding thousands of tonnes of food for humans each year.

Named after the galaxy of white stars on their flanks, there are nearly 50 species of Galaxias around the world, of which more than half can be found in Australia. Several species are known from only one or two locations, and up to 10 are critically endangered.

Scientific artwork by Francois Laporte of a Spotted Jollytail and a Common Jollytail Dessins des Poissons de Melbourne (Australia) d’apres des individus frais. Pour le Jardin des Plantes de Paris (Drawings of Fishes of Melbourne (Australia) from fresh individuals. For the Botanic Gardens of Paris). Scientific artwork by Francois Laporte, Le Compte de Castelnau, presented on 23 February 1880 to what is now Museum Victoria. The top specimen is the Spotted Jollytail (Galaxias truttaceus (then G.ocellatus)) and the bottom one Common Jollytail (Galaxias maculatus (then G.versicolor)). Count Castelnau was the first to scientifically describe the Spotted Jollytail, and Frederick McCoy (first Director of the Museum) described the Common Jollytail.
Source: Museum Victoria

The most abundant is the Common Jollytail (Galaxias maculatus) with the largest natural distribution of any freshwater fish, found across most of southern Australia, Tasmania, New Zealand, the Pacific Islands and parts of South America.

Two blue Common Jollytail fish Galaxiid species found in Victoria: Common Jollytail (Galaxias maculatus)
Image: Rudie H. Kuiter
Source: Aquatic Photographics

One green Spotted Jollytail fish Galaxiid species found in Victoria: Spotted Jollytail (G.truttaceus)
Image: Rudie H. Kuiter
Source: Aquatic Photographics

A Mountain Jollytail fish against a black background Galaxiid species found in Victoria: Mountain Jollytail (G.olidus)
Image: Rudie H. Kuiter
Source: Aquatic Photographics

In Australia this species is also known as Native Trout, and as Puyen in South America and Inanga in New Zealand. The distribution of Common Jollytails is assumed by some researchers to reflect their origin in Gondwana, the ancient supercontinent which included all the southern continents (also a feature of the Forest Gallery). However, Gondwana broke up 65 million years ago and the oldest known Galaxiid fossil is only 23 million years old. In contrast, genetic studies suggest there is ongoing mixing between populations of Common Jollytails on different continents, and that the original population in Australia migrated all the way to South America and to many points in between.

Common Jollytails are highly opportunistic, able to live in unpredictable water bodies, and tolerate salinity almost double that of sea water. They can also survive a range of water temperatures, enabling them to live in streams from southeast Queensland to the southwest corner of WA. The smallest adults mature at 5.7cm in length and the largest grow to almost 20cm.

A school of Common Jollytails in the Forest Gallery creek, Melbourne Museum. A school of Common Jollytails in the Forest Gallery creek, Melbourne Museum.
Image: Patrick Honan
Source: Museum Victoria

In autumn adults swim downstream to river mouths to spawn, waiting for a spring tide to lay millions of eggs amongst moist vegetation on the river banks. As the tide recedes, the eggs are left exposed for two weeks or more until the next spring tide, when they hatch and are washed out to sea. Here they spend up to six months through winter before swimming back upstream for the next year or so until they reach maturity. In Victoria and elsewhere, landlocked populations survive by migrating from streams into large lakes instead of the sea.

In Australia the whitebait fishing industry focussing on galaxiids closed in the 1970s, but it remains healthy overseas. ‘Whitebaiters’ catch the transparent juveniles as they swarm upstream from the coast, and in Chile alone the catch is up to 20 tonnes per season, while in New Zealand it may be more than 100 tonnes annually (one tonne of whitebait equals about three million individuals). However, studies show whitebaiters in New Zealand harvest a very small proportion of the potential catch each year.

People collecting fish under a bright light at night Live Exhibits staff collecting Galaxiids under permit at night. The fish are held in quarantine for six weeks to detect any diseases or parasites before being released into the Forest Gallery at Melbourne Museum.
Image: Patrick Honan
Source: Museum Victoria

Galaxiids feed on aquatic insects, molluscs and crustaceans, which unfortunately puts them in direct competition with introduced trout, which also prey on the galaxiids themselves. A joint Museum Victoria/Parks Victoria survey of the Victorian Alps in 2013 found that galaxiids had disappeared from many streams where they were previously abundant just a couple of decades ago, and research suggests introduced trout can clear a stream of its galaxiid population in as little as six months.

The prime way trout are introduced into streams is translocation by fishing enthusiasts. Redfin, habitat degradation and changes to stream flow also threaten many of the galaxiid species – the Pedder Galaxias (Galaxias pedderensis) in Tasmania is thought to be Australia’s most threatened fish species.

A roundworm inside (left) and outside of (right) a wild Common Jollytail fish A roundworm (Nematode) in situ (left) and removed (right) from a wild Common Jollytail, probably Eustrongylides species. These worms spend early stages of the life cycle inside fish and mature in waterbirds that eat infected fish.
Image: Alan Henderson
Source: Museum Victoria

Although the Common Jollytail is relatively secure, more work needs to be done to ensure the survival of other galaxiids. Common Jollytails, Spotted Jollytails (Galaxias truttaceus) and a range of other fascinating little fish can be seen schooling every day in the Forest Gallery at Melbourne Museum.

References

Barbee, N.C., Hale, R., Morrongiello, J., Hicks, A., Semmens, D., Downes, B.J. & Swearer, S.E., 2011, Large-scale variation in life history traits of the widespread diadromous fish, Galaxias maculatus, reflects geographic differences in local environmental conditions, Marine and Freshwater Research, 62(7):790-800

Chessman, B.C. & Williams, W.D., 1975, Salinity tolerance and osmoregulatory ability of Galaxias maculatus (Jenyns) (Pisces, Salmoniformes, Galaxiidae), Freshwater Research, 5(2):135-140

Gomon, M.F. & Bray, D.J., 2011, Common Galaxias, Galaxias maculatus, in Fishes of Australia, http://fishesofaustralia.net.au/home/species/2129

Pollard, D.A., 1971, The biology of a landlocked form of the normally catadromous salmoniform fish Galaxias maculatus (Jenyns): I. Life cycle and origin, Australian Journal of Marine and Freshwater Research, 22(2):91-124

Raadik, T.A., 2014, Fifteen from one: a revision of the Galaxias olidus Gunther, 1866 complex (Teleostei, Galaxiidae) in south-eastern Australia recognises three previously described taxa and describes 12 new species, Zootaxa, 3898(1):1-198

Comments (3)

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V.Dewsbury 21 November, 2016 19:18
I found your interesting article whilst looking for info on galaxias fish/fossils,especially in relation to Tasmanian (mountain/swamp/swan/golden/pedder) galaxias species for which I was looking for any natural history illustrations fossil photos/reference for my own illustration...John Wolseley also mentions/references them in his work from Iake Ina Tasmania. Not that ive been much into fish, myself (more of a bird fanatic) but the galaxias are a very interesting/curious little fish...and beautiful in their own way, love their sleek little form and variation of spottedness, Jollytail indeed, hadn't heard that name before... Ps Also had a chuckle at authors name, Honan, being my long diminished maiden name, (Patrick Honan turns up on convict list courtesy of ancestry etc!)not that Honans from my more immediate lineage are much fishermen/women or researchers, just don't often see it in print. Good luck for future work!
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Tarmo Raadik 2 December, 2016 07:52
Great article Patrick, and glad to see some more exposure on galaxiids! Two points though, 'jollytail' is an incorrect term for these fishes - the appropriate common name is 'Galaxias', e.g. Spotted Galaxias, Mountain Galaxias, etc. Also the image you list as 'Mountain Jollytail' is the Ornate Galaxias (Galaxias ornatus), found in the catchments around Port Phillip Bay and the area of the previous land bridge between mainland and Tasmania. Keep up the great work!
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Discovery Centre 5 December, 2016 14:34
Hi Tarmo,

Thanks for your feedback; it’s particularly welcome from a world expert on these fish. We’ll make the necessary changes to our records, labels and images.

 
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