big long branch appears to be touching/covering the top of the big stone on the left
Andrew, what I meant was, If your long term plan is to submit a picture of the aquarium to a contest, then you should be aware that in the '2D projecton of reality', a.k.a. the picture, the Branch that will have fissidens, will obscure whatever nice surface the big rock on the left, has on it's top. Is this your goal. It is a nice rock, and my personal subjective opinion is that there should be a bit of 'air' between the branch and the rock --- which, in a 2D picture, would result in the branch not obscuring anything.