It’s my understanding that dark matter and anti-matter are not the same thing. What’s anti-matter?
A metaphor:
Dark matter is that cousin whom you hardly know he’s there even when he’s there, which is somehow most of the time.
Antimatter is another cousin who is hardly ever around but when he is he’s loudmouthed, destructive, and even violent ... expect the cops to be called.
Antimatter meets matter. Kablamo.
Darin matter is something else. It is the name scientist give an unknown feature of ours and other galaxies that keeps them from spinning apart. Vera Rubin discovered that the stars in the galaxy don’t orbit the center like the planets in our solar system orbit the sun at different speeds. The Galaxy for the most part spins like a phonograph record as if it were a solid the only way this could happen is if there was considerably more mass that is unaccounted for. Now dark matter is physically visible as the mass warps space enough to cause stars in the background to appear elsewhere by gravitational lensing.