Hi
I am in the process of restarting a 30g. It was empty for at least a month. When I emptied it I didn`t clean or removed the gravel but I cleaned everything else.
I changed my mind (of course!) and restarted it last week. I just noticed that I have an assassin snail and a tiny java fern that survived! There was maybe an inch of standing water (whatever was in the gravel) only and they survived!
Wow amazing isn't it how creatures/plants survive. :) In fact it's down right scarey :-\.
I'll take this opportunity to remind everyone not to release fish/plants back
into the environment, no matter how much you think it is kinder to let them be free.
There are not only environment consequences but also laws against it.