I have one in my tank
They do eat till they are round, i thought he was sick because he finally came out of hiding one day and was big as a golf ball, but after two hours he was back to normal meaning 3-4 inches and proportionate for his size. I have a shell he hides in i see his tail and the only way in or out is the top, he swims in stays there and backs out the hole is barely big enough for him to fit in so it is funny to watch. But he is nocturnal and very different from my other fish. My raphael really likes shrimp pellets if i drop the in tank no matter the time of day he is out eating as much as he can find.