The other thing that fish will do apart from keeping lava down is be a ready visable reference on the "health" of the water if the fish are happy it is probably OK if the fish suddenly die then there has to be an explaination. They would also stop the water from going Stale ( keeping it moving)
We have a particuly dry time here over the last few years (seems to be all but over now though) So the local state offered a rebate to all these city folk to put a water tak on the side of their house ( They were banned several years ago after a scourge of denge fever was put back onto the mossis from domestic water tanks). I grew up on tank water but these new ones are only for washing, flushing and garden, your not authorised to drink it ( gotta love bureaurocracy) We have had people in at work complaining about tree frogs in their water, wondering how to get rid of them. But the bottom line is our tree frogs are pretty fuusy and only stay in clean water.
Carl
We have a particuly dry time here over the last few years (seems to be all but over now though) So the local state offered a rebate to all these city folk to put a water tak on the side of their house ( They were banned several years ago after a scourge of denge fever was put back onto the mossis from domestic water tanks). I grew up on tank water but these new ones are only for washing, flushing and garden, your not authorised to drink it ( gotta love bureaurocracy) We have had people in at work complaining about tree frogs in their water, wondering how to get rid of them. But the bottom line is our tree frogs are pretty fuusy and only stay in clean water.
Carl