Visitors with sharp eyes will enjoy trying to spot the young Silver Perch (Bidyanus bidyanus) in the watercourse of the Oasis Valley, Dubbo Regional Botanic Garden. The attractive fish are well camouflaged against the pebbles on the river bed. Counting them as they slip in and out of the shadows – now three fish – now eight - is a simple almost meditative pleasure.
Silver Perch are native to the Murray-Darling river system. They were once widespread and abundant but their numbers have seriously declined. This is due to a number of factors including habitat degradation and competition from introduced species such as carp and redfin.
Silver perch are listed as a vulnerable species in NSW and it is illegal to take them from the rivers or streams in the Murray-Darling Basin. The fish in the Oasis Valley were supplied when they were fingerlings by a reputable fish farm.
Silver perch are omnivorous, feeding on small aquatic insects, molluscs, earthworms and green algae. Adults usually reach 30-40cm and 0.5-1.5 kg.
Care was taken to establish a good habitat for the fish before they were released into the flowing waters of the Oasis Valley. A carefully chosen selection of native reeds and rushes were planted by local community groups last year, to cleanse and oxygenate the water.
A variety of snags (wooden logs) have been provided for the young fish to take refuge amongst, when threatened by visiting cormorants and herons.
The preparations have paid off. The young fish seem to be thriving. They have more than doubled in size since their introduction to the Oasis Valley watercourse late last year.
Silver Perch were chosen for the Oasis Valley to raise awareness of the need to look after our natural waterways and to give visitors, particularly youngsters an opportunity to observe a beautiful fish which has become less common in its native habitat.
By Ian McAlister & Karen Hagan