"Inhuman clicking" doesn't mean much to me- this is totally up to perception. Do you think inhuman clicking is too fast, too slow, in different spots, same spot, etc.
Even then, your success in botting can cause Jagex to crack down harder on methods used to evade detection, making it harder for those who helped you. I think by now you can see nobody is willing to hand you information for free.
I would use getGroundItems().getAll(), stream the results and filter through them for Tuna or whatever items. You can them sort this List using a comparator and your player's distance to the GroundItem.
EDIT: I read the question wrong, I would check out the Menu class.