hummm... i had gotten a snowflake about a year ago, he isnt to much bigger prolly 3-4 inchs longer, and he just comes to the top of the water when i put some krill in there for him, he swims around the top until he can't find any more food then he goes back into the rocks...never had him try to jump out either, i have a few openings in the back of my tank too.