I kept 6 nautili for a while because I thought they were 'cool' too. Huge mistake. After putting up a darkened and shrouded tank for them and installing photo developing room lamps, they proved to be as exciting as watching paint dry. They clung to the corners (and each other) and caves. And only came out to feed. Then, right back into the corners/caves. They fed easily on mollies, ghost shrimp, small crabs, bloodworms, and earthworms. But their inactivity always made the 150 look like I was keeping an empty tank running.