UFC star Derrick Lewis says he's exhausted and bit up after 2 straight days of rescuing flood victims in Houston ... telling TMZ Sports freezing water and swarms of ants are a huge problem.
We spoke with Lewis after footage surfaced showing "The Black Beast" carrying people who have been stranded due to the torrential rains from Hurricane Harvey.
"Basically, I'm just looking around and seeing anyone that need help."
Derrick says he put information on his Facebook page -- and if people reach out in need of assistance, he rolls out immediately .