@Chantal-Goetheer I didn't see it at first, but now I know the large fish is the mother. It looks as if she is looking at the shark with worry for her babies. If that is what you want, then I suggest having the kids play around the dangerous looking items.
I assume the kids are exploring their new territory, and mom just spotted the shark. However, not to get technical, angler fish live so deep that they are unlikely to be targets of sharks. I would focus on the fish hook or anchor as the threat, since, being so dark and deep, the kids would not have seen something like that and understand the danger, but mom perhaps would.
I think some distance between mom and kids would help with the feeling of urgency or danger.
Maybe less teeth in mom's mouth as well so the expression is clearer. And one thing I learned recently from one of the 3PP podcasts (on YT) is if you move the iris of an eye ever so slightly away from the edge of the eye, it changes a worried or shocked expression for the better.
Hope that helps!