How to Check Formalin in Fish at Home.

Formalin-treated fish can look fresh for days. These simple checks help you tell the difference before you cook.

1. 1.

   Look at the gills

   Fresh fish has bright red or pink gills; brown, grey or pale gills suggest age or chemical treatment.

2. 2.

   Check the eyes

   Clear and bulging is fresh; cloudy or sunken is old.

3. 3.

   Smell it

   Fresh fish smells mildly of the sea; a sharp, pungent or medicinal smell is a warning sign.

4. 4.

   Press the flesh

   It should spring back; rubbery or unusually stiff flesh is a warning sign.

5. 5.

   Watch for flies at the stall

   Flies tend to avoid fish treated with formalin.

6. 6.

   Use a formalin test strip

   Wipe the strip on the skin or gills; a colour change means formalin is present. Kits are inexpensive and sold online.