During making, use of TAI (sold by the Formulary) is useful to reduce fog. See the formula by Jim Browning here or on his web site for an example of how to use it. It is measured in milligrams / mole of silver. If your fog forms during or after making in spite of TAI or without TAI, use of PMT will work, but in very very low levels. This is usually at the level of 0.1 to 1.0 mg/mole of silver. Very low. BTAZ usually does not work well added to emulsions.
If you have fog with AJ-12, you have probably over washed it and there is not enough residual halide left to buffer the vAg. Use the above solutions I propose. Remember though that you will lose speed. Every milligram of PMT might cost you 1/2 stop or 1 stop in speed so be careful.