It would be difficult to evaluate this film without referring to apartheid in South Africa. The parallels between the alien "prawns" and the black South Africans are blatant. The location of District 9 where the prawns were kept was very recently a neighborhood from which its inhabitants were evicted. Humans become increasingly inhumane, revealing our darkest traits. Wilkus, the human protagonist, cares little about the rights of the prawns, not even their right to life. When he serves eviction notices, he does not care if the aliens can understand or comply if they do understand.
The aliens lack of hostility but are treated brutally. The are imprisoned, denied the right to work, to move. They are even denied the right to procreation with their egg/pods aborted when discovered. The humans claim that the prawns do not care about their offspring, despite evidence of the opposite in Christopher's care for his son.
The humans are drawn by their weapons technology, which only the alien species can use. Only those who wish to exploit the aliens will interact with them. Their only desire is to use the technology for destruction. There is little to no concern about the prawn's welfare.
Wilkus is poisoned when he tampers with vial of liquid which two aliens had been filling. This poison begins to mutate his DNA. As he transforms into a prawn, he discovers the humanity in both the aliens and himself. The prawns instinctivly flock to rescue him when he is in danger. At the end, he is identifiable only by his one blue eye.