Would metal ornaments in a (freshwater) fish tank harm the fish?
If so, could you coat them (the objects, not the fish) in some way to make them harmless?
Aluminium/Aluminum or steel for example? A nice shiny piston or a bike chain? Not heavy metals, obviously, but I liked the title.
(the other half got a new tank for the prezzie-heavy festive season, and being the sort of nerds we are, we were considering "alternative" tank ornaments).
cheers