There are tastier fish, I'll admit, but for AP it is a great fish to grow. I rarely have any problems with diseases or fish death, apart from the occasional fish jumping out of the tank. It can withstand extremes, although I think Tilapia in the Murray is a stretch of the imagination as it is a tropical fish, so the cold temps. in Southern Australia wouldn't support it.
Just to answer the question about muddy tasting fish. I have eaten Tilapia from a local fish farm that have been in a muddy looking dam. The taste was not good. I have eaten carp in Java and also Gourami. In both cases, the fish were farmed in clean water and tasted great. I was also told when I lived in Java that freshwater fish were always put in clean tanks for a few days prior to being sold for market or eaten. In many Asian countries fish are kept in tanks in restaraunts so that they are freshly killed before consumption.
With Tilapia I have found the taste is better if they are not fed for a few days before eating. My tanks are all filtered now with 200 litre swirl filters and matala foam filters, settling tanks etc. so water quality is always crystal clear.
Yep, off flavours are a byproduct of blue-green algae... which is why they are prevalent in pond/dam based aquaculture...
Some Asian countries have also been known to spray deisel on ponds/dams for mosquito control... which can also impart an off-flavour...Geosmin and 2-Methylisoborneol (MIB), have been identified as the cause of a majority of off-flavor incidents. Geosmin and MIB are secondary metabolic products of some species of bluegreen algae and actinomycete bacteria.
MIB causes a flavor to be imparted to the flesh described as "musty" or "lagoon"... and geosmin results in "earthy" or "woody" flavors.
These two compounds are extremely potent. Geosmin and MIB can be tasted in the water by humans at concentrations of 0.01 and 0.03 parts per billion (ppb), respectively.
High temperatures, high stocking densities and high feeding regimes also contribute....
All the above are common to Tilapia production in particular....
Purging in fresh water for a minimum of 3 days is, or should be, a standard practice...
I have a sand filter on my pool. Could this kind of pool filter be used sucessfully in an AP system? I note the reference to a "biologically active sand filter" in the abstract below:
I had never heard of these two compounds as being responsible for the odour/taste associated with pond reared fish.
As I am interested more in deep water culture Aquaponics, I'm always on the lookout for DIY ideas for filtration.
The removal of taste and odour compounds from drinking water is a constant challenge to water authorities. Although adverse odours do not present a risk to human health, their presence often leads to a misconception that the water is unsafe for drinking. 2-Methylisoborneol (MIB) and geosmin are the most common causes of earthy/musty odour, and are not easily removed by conventional treatment processes. MIB and geosmin can be removed through biologically active sand filters. Experiments were conducted using laboratory sand filter columns using sand taken from South Australian water treatment plants. Sand with a well-established biofilm taken from a 26 years old filter was capable of removing MIB and geosmin to below detection limit after 11 days of operation at an Empty Bed Contact Time (EBCT) of 15 min. Sand without an established biofilm removed 60% geosmin and 40% MIB after 154 days of operation at 15 min EBCT.
I purge tilapia before cleaning them as well. I also purge channel catfish as well. Channel cat seem to always have a "muddy" flavor regardless of the water they come from unless you purge them. At least that has been my experience throughout the years.
Kellen Weissenbach | Hatchery Manager | White Brook Tilapia Farm | Kansas City, MO USA | www.tilapiasource.com
To have better tasting fish, it is better to purge the fish before you kill and eat it. Being an aquaculturist myself, if we purge the fish for at least 3-7 days, it will remove the muddy taste.