Madagascan mixed species

Madagascar giant day gecko, Phelsuma grandis, and Madagascar hissing cockroach, Gromphadorhina portentosa

In the Discovery Centre

Wouldn't the gecko eat the cockroach?

I couldn't find anything to suggest that an adult hissing cockroach would be eaten by a day gecko. Certainly, neither of the pair of geckos in the display showed any interest in the group of cockroaches at all.