In a statement released Tuesday, the UFC said all fighters on the card in Brisbane, Australia, were tested by an independent third-party laboratory. Only Silva failed.
"Although Silva is on a medically approved regimen of Testosterone Replacement Therapy (TRT), and had been in compliance with therapeutic guidelines on all pre-fight tests performed prior to the event, the results of his test on the day of the event indicated a level of testosterone outside of [the] allowable limit," the statement said.
Silva's suspension is retroactive to the date of the fight. The Brazilian's record will reflect a no contest rather than a draw, and his portion of the fight of the night bonus instead will go to Hunt.
On Facebook, Silva said that months before the fight, UFC approved his use of TRT under the care of Dr. Marcio Tannure, medical director of the Brazilian MMA Athletic Commission and UFC in Brazil. Two weeks prior to what would be one of the year's best brawls, Silva said he underwent exams required by the UFC and "my testosterone level continued to be low, so I was recommended by the doctor to increase the dosage."
"I'm cool because I know that the mistake was not made by me," he wrote. "I never tried doing anything wrong for my fight."
This is the second time Silva has tested positive for a banned substance.
The 34-year-old Brazilian, who competes with the pituitary gland condition acromegaly, tested positive for Boldenone after a contest in 2008. He denied taking the drug, which carried a one-year suspension and a $2,500 fine from the California State Athletic Commission, and unsuccessfully challenged the suspension in court. Silva's manager, Alex Davis, blamed the positive test on an over-the-counter testosterone booster.
Silva challenged for the UFC heavyweight title in May, losing by stoppage to champion Cain Velasquez at 1:21 of Round 1.