Rob McCormack
Off Flavours can be quite common in freshwater fish and can easily be removed if proper procedures are followed. When we talk about off flavours we are generally talking a muddy or earthy type taste to fish. The causes of this can be varied but generally they are caused by geosmin and 2 methylisoborneol. These are compounds produced by blue-green algae and some bacterias. Silver Perch are very susceptible to off flavours as they eat weeds and algaes in the pond and also consume large amounts of mud and sediments as they feed off the bottom of the pond. Bass and yellowbelly are less susceptible as they eat more live food but can still become tainted when they eat small Atyidae shrimp which they suck from weeds, etc. and consume weed or mud as a bicatch.
Yabbies generally do not retain off flavours like fish do however if they are fed aquatic weeds as a primary food source they can retain an off flavour. Native primrose is readily consumed by yabbies but does result in an off flavour and we no longer use this weed as a food source.
It is essential that commercially grown fish be purged prior to sale to ensure a premium flavour every time. In the past server damage has been caused in the market place by unpurged fish being sold. These fish referred to as road kill by commercial farmers can destroy the good name of a excellent eating fish like Silver Perch. A good Silver Perch is Excellent eating and equivalent or better than most of its salt water competitors and a week in a purging system is all that’s required to ensure your fish is excellent.(See Purging)