The Blackwood River is the largest river in the South West. Rainbow trout are stocked into the main river (yearlings) and tributary brooks (fry) each year. Redfin perch are common and if caught must not be returned to the river. Above Bridgetown the river runs through farmland and is salty. The river water is less salty below Bridgetown and Alexandra Bridge as the river passes through state forest and national park where forest runoff is largely fresh. Trout can be caught above Bridgetown but the upper reaches of the river are a stronghold of redfin perch which prefer deeper pools with slow currents and are more tolerant of the high summer water temperatures. Redfin can be taken by a variety of methods including spinning with hard body lures, jigging soft plastics in among the snags or bait fishing with worms. Below Bridgetown trout are more common and can be caught down as far as Alexandra Bridge. Trout also inhabit some of the larger tributaries such as Balingup, Nannup, Hesters and St Johns Brooks. The most popular fishing method for trout is spinning using small hard body lures, and most spin fishers target the longer runs and deep pools. There are many logs and branches lying in this river. Fly fishers often target faster runs and the base of falls and rapids. Popular flies include various minnow patterns swung across and downstream in fast water and prospecting pocket water with a variety of nymphs such as gold bead flashbacks.
During summer dry fly fishing can be productive using hopper and caddis patterns. There are many access points where road bridges cross the river. The road from Balingup to Nannup has many access points to Balingup Brook and the main river. There are excellent campgrounds at Wrights Bridge, Sues Bridge, Chapman Pool and Alexandra Bridge and kayak fishing is popular. Access to the riverbed in summer can be difficult as the banks can be high and steep and there is a lot of dense vegetation, including blackberries. Best times to fish are in late autumn when water temperatures fall and river levels rise and in late spring when water levels start to fall.