Not necessarily. Dark matter could be made of small dense objects. Because they are small, we wouldn't see absorption of light. And because they are small, they will very seldom collide. These kinds of object are called MACHOs.

Based on observed dimming events while monitoring many stars, we have ruled out brown dwarfs as more than 20% of the total. Other possibilities still remain, but none have shown evidence of being sufficient to explain dark matter. However we have not ruled out the possibility of it being something that we haven't thought of yet.