Second puzzle in the marinelife series designed by Akio Yamamoto, this puzzle is (much?) more difficult than the cast seabream: the shapes of the pieces make the puzzle a bit confusing and if your puzzle has some flaws (it can happen with mass-produced puzzles!), then it's pretty hard to discover the moves.
I like the design of a shark going through jaws without being bitten ;-)
The puzzle is less easy than what you can think at a first glance because you need very small moves and good precision when you manipulate it so that it can move. So if you're blocked, try to make small and slow moves, and maybe it will help you....And obviously you need some idea to progress.
It's worth more a level 2/6 difficulty in my mind. I think it's an interesting puzzle. So try to buy it, you won't regret!