CFR › Title 21 › Part 556 › §556.66021 CFR §556.660Verified against eCFR.gov as of June 20, 2026View official text on eCFR.gov ↗Copy link(a)[Reserved](b)Tolerances. The tolerance for sulfamerazine is:(1)Trout. Edible tissues: Zero.(2)[Reserved](c)Related conditions of use. See §§ 520.2218 and 558.582 of this chapter.