My freshwater molly seems to be having problems swimming, it stays near the bottom of the tank and it struggles to swim higher but it cant. What is wrong with it and what should i do to help it?

Franz,
Please read up about tropical fish. The molly is a brackish water fish. In that environment fresh and salt water meets, and therefore, you should add some ocean salt.

But before you start adding salt please up on the correct amount and how to add it.

aquarist with 9 tanks

with mollies there like quppies you should always double the aquarium salt