Among the most stunning of fish in the streams of tropical Queensland are the cling gobies. The males of these species are brightly coloured for weeks to months each year. These high-end dress standards are most notable in male versus male contests and serve to attract mates during the breeding season. About ten species have now been recorded in Australian waters.
(See NPAQ concerns about the proposed Wangetti Trail including potential for sedimentation of the Critically Endangered Opal cling goby habitat. https://npaq.org.au/current-issues/wangetti-trail-proposal/)
The smallest of these species is Birdsong’s cling goby which rarely attains 4 cm in total length. Indeed, most of the cling gobies reach only 4 to 6 cm in length. Of the larger species, the most common is the rabbit-head cling goby which achieves a whopping 11 cm in length as a male and 13 cm or so as a female. The rabbit-head cling goby can be observed with the aid of a snorkel mask, in fast, flowing water and especially through the wall of bubbles underneath toppling cascades. The rabbit-head and indeed many of the cling gobies specialise in grazing thin biofilm surfaces on rocks. If you are keen to see them in the wild, the rabbit-head can sometimes be seen on the upstream of the main swimming hole at the ‘Boulders’ in Bunna Binda Country in Wooroonooran National Park (near Babinda) or in Jabalbina Country in Emmagen Creek within the Daintree National Park just north of Cape Tribulation.
These fish occupy stream habitats and are usually found in steep coastal streams in high rainfall areas. The Wet Tropics is the stronghold for cling gobies in an Australia context but this is just a small subset of the distribution of the cling gobies which are widespread in tropical island streams in the tropical Pacific region including Indonesia, the Solomon Islands and Fiji.
All cling gobies are no-take species in Queensland under the Fisheries Act and three species (including Birdsong’s cling goby) are vulnerable species under the Nature Conservation Act. The Opal cling goby is listed as critically endangered nationally under the EPBC Act. This species has recently been recorded breeding in a stream in Yirrganydji Country just north of Cairns. Ladies will be happy to know that it is the female who initiates the ritual followed by the male wasting no time in performing a high energy courtship. He jumps from the top of rock to rock and uses the high points to capture valuable light that has crept through the rainforest canopy. This facilitates a display of blue iridescence angled toward the female (https://www.youtube.com/watch?v=omjuck8DiLM). And then off to a cave where the male will spend a couple of days tending the eggs before hatch. The larvae drift down on the fast flow and out to sea to grow before returning to a coastal stream to commence juvenile and adult life.