I have a 10 gallon tank with 3 adult mollies (1 male, 2 females), 1 platy (male), and 3 baby mollies (all female; one of them is still in a breeder net as she is too small; the others were moved out of the breeder net a month ago and everyone was fine and happy).

The male molly is usually quite active and aggressive towards the 2 adult female mollies, and the others keep very much to themselves. All of a sudden all my fish started hiding in the plants.

What could be causing this behaviour?