From the designer....
"In the summer of 1997, I saw two horse mackerels that had somehow managed to get into the sardine tank at the aquarium. The sight of these two fish being unable to blend in with the shoal of sardines made them seem as if they were on an expedition of self-discovery. What sort of adventures will they have?"
Imagining this led to the conception of six Cast Puzzles based on oceanographic subjects. A small horse mackerel captured by a shore crab. See if you can help it escape.
Separate the 2 parts and put back to start!