Tsessebe (Damaliscus lunatus).
East African antelope ending with opi, would be the Topi.
Oribi
That would be the Impala.
DUIKER
Nyala
Gnu
Oribi is a small African antelope
kudu
· Duiker · Impala
dikdik
I think the answer is SUNI
Gnu is a three letter word for an African antelope
Kudu :striped African antelope