One Fish, Two fish … Five Fish, New Fish!

Five whitebait may not seem like much of a catch, but the Museum was very pleased to get them.

Horizons Regional Council looking for fishes in the Tutaeika. Photo: Damien Wood.

Horizons Regional Council looking for fishes in the Tutaeika. Photo: Damien Wood.

Perhaps a proper whitebait net would have helped, instead of two aquarium dip nets, but we were trying to catch adult whitebait, or īnanga, for the Museum’s new aquarium. The word “whitebait” actually refers to the juveniles of not one but five different species of native fish; young īnanga are the most common of those five. Adult īnanga are attractive little fishes about the size of your finger. Their scientific name Galaxias maculatus (maculatus means spotted) describes their leopard-like spots, and they have an iridescent greenish stripe. In the aquarium they hover in the filter current in a tidy shoal.

Native fishes are mostly nocturnal, so at 11 pm on Saturday night the Curator of Natural History was wading up the muddy Tutaeika Stream in Aramoho, being eaten by mosquitoes, peering into the water with a powerful head lamp. The Tutaeika has a history with local hapu as a food-gathering site, but in the daytime it doesn’t look like much: it emerges from a culvert, flows like a drainage ditch through open fields with no shelter, and runs for a short distance behind backyards and Aramoho School, fringed with weeds, before emptying into the Whanganui River. But at night I counted at least four species of fish—īnanga, a middle-sized eel, banded kokopu, and common bully. A recent fish survey by Horizons found koura (freshwater crayfish) there too, and the introduced pest fish Gambusia—impressive diversity for a neglected suburban stream.

Adult īnanga ('Galaxias maculatus') Credit: Whanganui Regional Museum

Adult īnanga (‘Galaxias maculatus’) Credit: Whanganui Regional Museum

Each year, the whitebait that escape the nets head upriver to sheltered streams to feed and grow over summer. By autumn, after eating voraciously, īnanga are the size of the adults in our aquarium, and head downriver to spawn. They lay eggs around the base of grass and reeds in the estuary, and most then die. The young īnanga head out to sea for the winter after they hatch, and return in spring as whitebait. So most īnanga live for only a year—the ones in our aquarium won’t be spawning, so will live for two or three years.

The Whanganui Regional Museum’s new native fish aquarium. Credit: Whanganui Regional Museum

The Whanganui Regional Museum’s new native fish aquarium. Credit: Whanganui Regional Museum

We set up our aquarium to mimic the streams around suburban Whanganui: the fish are natives, but the lush greenery is all invasive weeds, plants originally imported by fishkeeping hobbyists and now choking our waterways. It’s sitting in the museum atrium, and seems popular—green swaying plants and darting fish are almost hypnotic.

Part of the job of a museum is to document and preserve the natural history of its area, so in 100 years locals and scientists can see what’s been lost or gained. Our job is also to raise awareness of treasures that would otherwise be overlooked; treasures that might be in your backyard, especially if you live in Aramoho.

Mike Dickison is the Curator of Natural History at Whanganui Regional Museum.


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