So far they've gone most savage for the tubifex worms- the funniest was watching my tiny guy desperately grab a heap out of mid air, trying to chomp the impossibly huge heap up, and regretfully letting them go after a struggle. Often he'd grab it back 3 or 4 times before he accepted defeat.

They've gone from active to insanely active.

They're rarely not on the move. If they're not plunged into a plant or decoration, mouthing away, they're playing endlessly with each other, often out in the clear open. It's nice to watch them weave and follow after each other- sometimes so fast I'm afraid they'll bang into the tank wall! All the while clicking though, so I must be doing something right.
