That is the outlet for the canister filter the tank comes drilled.

My trick with java fern is to pretend it is not there.

Basically there is no special lighting no fertiliser or any funny substrates infact it should never be buried in the substrate. It does best when you attach a plant to bog wood with a rubber band with time the rubber band breaks down and when this happens the fern is attached to the bogwood. The other thing is to try and keep the nitrates down you don't need to go over board with water changes just keep the nitrates below 25ppm and also watch the phosphates.

I do not do anything fancy to get this stuff to grow it is actually the only plant I have ever been succesful with so that may be of use to you basically don't do what you have to do to keep other plants because I certainly don't.

__________________
Alan

Thweeerp!