Species Focus

Estuarine Clingfish (Trachelochismus aestuarium)

September 12, 2024
Clingfishes are a remarkable family of cryptic fishes found worldwide. They are small, flattened, and possess a sucking disc, a modification of their pelvic fins, on the underside with which to cling on to things.
Clingfishes are a remarkable family of cryptic fishes found worldwide. They are small, flattened, and possess a sucking disc, a modification of their pelvic fins, on the underside with which to cling on to things.
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Clingfishes are a remarkable family of cryptic fishes found worldwide. They are small, flattened, and possess a sucking disc, a modification of their pelvic fins, on the underside with which to cling on to things. Together, these features give a fairly good clue of where to find them - hiding in small and hard to access places, and where tide or currents require their ability to hang on. This usually means shallow marine environments. And in the case of the estuarine species, this of course includes estuaries.
The estuarine clingfish is a newly discovered species. It was only scientifically described last year, bringing the total number of endemic clingfishes in New Zealand to 14.

This clingfish is found coastally New Zealand-wide, but particularly in shallow, sheltered bays and in any of the northeastern estuaries. An empty cockle or mussel shell is a suitable hiding place. In fact, this species is found further up New Zealand estuaries, more than three kms, than any other clingfish species worldwide.

This clingfish lays its nest on the underside of a rock or empty shell, where eggs from multiple females may be laid. The male will then assume parental control, guarding them until they hatch one to two weeks later. Aeration is also vital due to them often living in sandy or silty environments.

While this species is known to be found down to as deep as 29 metres, it is far more common to be found in the upper three to four metres. Because of this, and as tides can be three metres high, clingfishes can endure periods between tides out of water. But in order to do so they must at least seek refuge in a damp rock or clump of algae to prevent completely desiccating in the sun, and where they secrete a layer of mucous to keep their gills moist.

Though very small in size at 20-40 mm, and living only a few short years, the estuarine clingfish is an exciting new addition to the crypto-benthic fishes in New Zealand’s waters, and a boon to rock-poolers, fish seekers and macro divers alike.

Fast Facts

1. One of two clingfish species newly described within the last year in New Zealand.2. The sucking disc on the underside is typical of this family.
3. Can be found in brackish waters over three km up estuaries.
4. Can quickly change its body colouration to match the background.
5. Lay hundreds of eggs on the underside of shells and rocks.
6. Unlike kelp-living clingfishes, this fish will guard the nests and aerate them until hatching.
7. By secreting a mucous, it can withstand periods of being out of water.
8. From the Latin aestuarium, a tidal inlet of the sea.

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Paul Caiger

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