2.6.2.2. Determination of trimethyl-amine nitrogen (TMA-N). Trimethyl-amine nitrogen (TMA-N) was estimated by a slight modification of the Conway Microdiffusion Method (1968). The fish fillet sample (25 g) was chopped and mixed completely with 75 ml of distilled water in a 250 ml beaker. A few drops of 2N hydrochloric acid (HCl) were added to adjust the pH reading to 5.2; this was followed by heating at 70 C and cooling to room temperature. Then, the sample was filtered into a conical flask with the aid of Whatman filter paper (No.1). 0.025N HCL (2 ml) was transferred to the central compartment of the micro diffusion dish with the aid of a pipette; this was followed by the addition of the extract (2 ml) and 35% formaldehyde (0.5 ml) with saturated K2CO3 solution (1 ml) into the outer ring. The dish was covered immediately with a glass plate and the set up was left at room temperature for 24 h. The HCL in the inner compartment was then titrated with 0.025N NaOH using 2e3 drops of methyl red/methylene blue indicator. The result was expressed in mg TMA-N/100 g of fish sample.