According to this NPR article, it currently is legal for ICE to detain you if you are visibly ethnic:
A federal court agreed, ruling that agents can't rely on factors such as race, speaking Spanish, wearing workman-like clothes, and location [...] to meet the standard of "individualized suspicion."
But in September, the Supreme Court paused that previous ruling, saying immigration agents can use those factors as reasonable suspicion to stop someone. (Legal proceedings continue on this case, however.)