Muddy flavour of tilapia could be due to excessive phytoplankton used as food by the tilapias in the pond. Try to substitute with pelletted feed.

Dear Dr. Abdul,

Thanks for the reply, but in here we dont muc practice such aquaculture practices. They just stock fingerling is natural resrvoir and then catched after some period, so we dont give food etc.

I agree with Peter Howgate that 2-methylisoborneol (musty, moldy) and geosmin (earthy) are the likely causes of muddy odors in farm-raised fish.  Controlling the cyanobacteria is an important means to control the muddy odor issue. If that can not be done, then there are studies showing that depuration can remove the odors.  Both 2-methylisoborneol and geosmin are difficult chemicals to remove. They cause odors in water at about 10 ng/L and require advanced oxidation (e.g. ozone)  for destruction.

Dear Andrea & peter

Are there any analytical methods to determine above chemicals?

Both geosmin and 2-MIB can be measured at ng/L concentrations through solid phase microextraction (SMPE) and GC-MS.  A method and references for water are described in our article.

Jo, C-H., A.M. Dietrich, J.M. Tanko. Simultaneous degradation of disinfection byproducts and earthy-musty odorants by the UV/H2O2 advanced oxidation process, Water Research, 45: 2507-2516, 2011.

 Please refer

Preventing Off-Flavour Tilapia

Off-flavour in cultured tilapia is caused by micro-organisms in the water, such as algae and bacteria, which causes the fish to have an earthy-musty, metallic, sweet-sweet or muddy taste. It is important to note that not all micro-organisms in the water produce off-flavour as phytoplankton and zooplankton are important part of the fishes’ diet. The development of these undesirable micro-organisms such as geosmin is usually caused by excess feed on the bottom of the pond and not by the fish ingesting mud. These off-flavour producing micro-organisms are usually ingested or absorbed through the gill or skin of the fish.

It is of paramount importance that farmers engage in taste testing before their fish are marketed. This is ideally done by cooking fish in a micro-wave oven for about five minutes without seasoning.

Preventative Measures Remove fish from tanks

Off-flavour taste in cultured Tilapia can easily be prevented by good cultural practices, which include the following:

Feed fish properly. Feed should be evenly distributed around the perimeter of the pond.

Maintain good water quality.

Farmers should ensure that fishes are not over- fed resulting in the formation of excess feed in the bottom of the pond thus producing these off- flavour micro- organisms.

Adequate exchange of water through the cultured system to remove unused nutrients and minimize the growth of off-flavour causing micro-organisms

Corrective Measures

Remove fishes from off- flavour ponds and place in clean ponds or tanks for 5-14 days. Fish should be fed to prevent weight loss.

Add salt to the flowing water in the tank containing the off-flavoured fishes. A salinity of 10 ppt. is sufficient to destroy the micro- organisms yet harmless to the fishes