For a thorough description of cannulation techniques for marine fin fish please refer to Fisheries Western Australia publication titled "Fish Cannulation Techniques" within the AquaInfo series. Dry artificial diets for silver perch are available in WA. Fingerlings (0.5 g) are initially fed three to five times per day with a crumble of around 2 mm diameter, comprising 35 per cent protein. Grading is very important and is continued at a frequency of every seven to ten days until 50 g or three to four months old (when fish are housed in tanks). Automatic grading equipment is now available to make this task easier. Often the fingerling phase is conducted in ponds, and if so, it is best to grade once only at the completion of the fingerling phase (S. Rowland, pers. comm.). Usually 60,000 to 100,000 fingerlings/ha are stocked into aerated nursery ponds and fed up to five per cent of body weight per day. With proper grading and heavy culling it is possible to achieve 0.75 - 1 g per day growth at 25 o C in the fingerling phase. In WA there appear to be insects (not present in the Eastern States) which are effective predators on silver perch fingerlings. To reduce mortalities from predation, the nursery phase should be completed in tanks (G. Whisson, pers. comm.). |