Dark matter can’t be detected in any way, but we know it exists because scientists tell us so, and they are never wrong.
No, the evidence for dark matter is strong, though not conclusive. Dark matter is matter that does not interact with electromagnetic fields (light) but has mass. It's presence is inferred from the observed large scale distribution and velocity of ordinary matter. If you have an explanation for these observations that is consistent with the laws of physics (i.e., consistent with observations on the scale of the solar system) book your reservations for Stockholm.
Same with anti matter?