salmon and tilapia are ok but i think the orange roughy is better. i have never heard the 1 time in 6 months thing that sounds rediculous to me. i look at it this way. i know a few guys who swear by it. they do this every year. just like they juice and practice other unhealthy diet traits. but it had is pre contest prep benafits. there are plenty of people also that eat a wide variety of sea food several times per day their whole life. there are entire countries that do this. i understand that most of what they eat has less than half the mercury content of orange roughy but the 3 months out of the year vs. every day of your whole life has to mean something.
i think it all boils down to what works for you and how much risk over all are you willing to take. the vast majority of todays top athletes in sports like wresteling, bb'ing, and pl'ing are causing serous damage to their bodies. with extreme amounts of food, and drugs. it seems as if the only possible path to success is to cause the damage now during your climb then once you reach your personal best and start to go backwards it is time to try to save as many years of life as you can. even on an amature level the cruel reality is there.
this is the rout that i follow.