WE ARE IN SERIOUS NEED OF A COUPLE MORE ISLANDS.
There are several different formats incress the # Of Habitats. Maximizing space with these formats, space is an issue.
Here are (3) ideas to fix this problem his could potential help.
(1) INCRESE the number of Monsters each can hold. With this it would only be temp. And concerns of the upgrade cost could be an issue especially with (Legendary)
(2) Another idea would be to RETIRE some of the lesser used weaker monsters.
(3) ISLAND Add Another Island.
THIS IS BECOMING A BIG PROBLEM EVEN WITH THE MAX NUMBER OF MONSTERS ON EACH.