Let p be a fixed prime. A triangle in F n p is an ordered triple (x, y, z) of points satisfying x + y + z = 0. Let N = p n = |F n p |. Green proved an arithmetic triangle removal lemma which says that for every ǫ > 0 and prime p, there is a δ > 0 such that if X, Y, Z ⊂ F n p and the number of triangles in X × Y × Z is at most δN 2 , then we can delete ǫN elements from X, Y , and Z and remove all triangles. Green posed the problem of improving the quantitative bounds on the arithmetic triangle removal lemma, and, in particular, asked whether a polynomial bound holds. Despite considerable attention, prior to this paper, the best known bound, due to the first author, showed that 1/δ can be taken to be an exponential tower of twos of height logarithmic in 1/ǫ.We solve Green's problem, proving an essentially tight bound for Green's arithmetic triangle removal lemma in F n p . We show that a polynomial bound holds, and further determine the best possible exponent. Namely, there is a explicit number C p such that we may take δ = (ǫ/3) Cp , and we must have δ ≤ ǫ Cp−o(1) . In particular, C 2 = 1 + 1/(5/3 − log 2 3) ≈ 13.239, and C 3 = 1 + 1/c 3 with c 3 = 1 − log b log 3 , b = a −2/3 + a 1/3 + a 4/3 , and a = √ 33−1 8, which gives C 3 ≈ 13.901. The proof uses the essentially sharp bound on multicolored sum-free sets due to work of Kleinberg-SawinSpeyer, Norin, and Pebody, which builds on the recent breakthrough on the cap set problem by Croot-Lev-Pach, and the subsequent work by Ellenberg-Gijswijt, Blasiak-Church-Cohn-GrochowNaslund-Sawin-Umans, and Alon.