I love the whale shark as well! I love all sharks in general actually. I've always loved watching shark documentaries on Disney+, so it's an easy choice for me haha
All of the crabs! They're pretty fast and fun to chase after, and they sell for a good amount too! It's also fun to watch them wiggle their legs around. I had to choose just one favorite it would have to be the mitten crab. They've been the most challenging to find, at least for me.