Sorry to let ya down gemini, but 10 gal is not near big enough to keep a peacock mantis long term. Maybe if it was 3 inches or under, but they do grow. As for feeding it, it's actually relatively cheap. You just buy fresh uncooked shrimp/squid from the grocery store. Live treats like snails/hermits are good (maybe once a week or two). You should soak the frozens in selcon once in a while too.