I am sure you have heard people say they don't like the taste of freshwater fish.

The biggest criticism regarding the taste of freshwater fish is usually, "they have a muddy or earthy taste," or they have a "musky pond flavour."

These are often called "off-flavour" in the aquaculture industry.

If you are not aware, Australian freshwater fish are commercially farmed in many countries.

So, what causes these flavours, and what can be done about it?

It's usually because freshwater fish "drink," get their freshwater from swallowing some, but also through their gills and skin.

This means they will sometimes take in any flavour influencing taints that are in the water.

The science behind all of this is way too complicated to go into here, but if you really want to know check these links. 

NSW Government about silver perch aquacultureand World Aquaculture Society

To really simplify this I'll ignore all the VAST detail and just say, "this is usually caused by a couple of compounds produced by algae." Even if the water is clear, these compounds can still be present.

Consumers demand perch that have a delicate sweet flavour.

Fish that have undesirable flavours are not marketable.

Off-flavours in fish present no danger to consumers, but off-flavoured fish sold in the marketplace, can result in the reputation of freshwater fish having unplesent "off-flavour." 

While pond management can under certain circumstances, decrease the incidence of off-flavours, in most production systems the perch must be purged.

Perch are held in a purging system or holding tank where they are held for about a week, depending on conditions.

Fish held in very clean water will "purge" the off flavour.

Clean water will eliminate off-flavours. 

Also, salt (5-10 ppt) is included in the purging water to reduce stress, to prevent fungal infections and kill ectoparasites.

The salt has no effect on the taste of the fish.

This is based on science.

Freshwater fish do not change flavour when held in salted water.

They regulate the amount of salt in the tissue through a process called "osmoregulation." If you want all the complicated science click here So, when you buy silver perch, jade perch, or Murray cod at a restaurant it should taste great.

If it doesn't, the farm did not purge correctly.

You have fish in your dam and you want to enjoy the eating quality after all the time spent waiting for them to grow.

Catch and try one fish.

If the water is very clear, the fish will probably taste good, if it doesn't, you can purge them yourself if you have a tank with water that you can keep clean.

If you can't purge yourself, then try another fish after some time has passed.

Sometimes you might just have to wait longer.

Eventually the fish will have the perfect taste.

Now is the time to catch a few and freeze some for later. But don't forget to eat one NOW !