What to feed my water hyacinth?

You have mosquito larvae before they hatch out and its the adults that fly that lay the eggs in the water , any chance you can get one or two goldfish as these will sort them out.

in a small container a couple of drops of cooking oil (tea spoon full ) will also stop they as they suffocate because of the oil film on the top of the water

Spruce

Spruce

 

Never had much real success with water hyacinth myself, I think our summers are just not consistently hot enough for them to do well.

For overwintering they used to advise potting them up in mud until the weather warms up in spring, guess that mimics the dry spell in the tropics.
Never tried it, so if it fails, you didn't hear it here.

 

Thanks, Pete, that sounds logical