I just had a question about decaying leaves in a semi-planted aquarium. Is it necessary to remove them ? Do they affect water quality by turning into ammonia or anything harmful to fish? Thank you.
Depends on the size of the tank and what is living in it (snails like to eat dead plant material). The larger the tank the less likely that a leaf here and there would do anything to the water. If you want to be safe though, it can't hurt to remove the leaf.
i remove dead and dying vegetation in my tanks mainly because it looks way better to not have rotting leaves, etc in the tank. secondary reason is to keep the tank's water quality up and keep the inhabitants as healthy as possible.