If you put it in a bowl and cover it in boiling water for a few minutes it
will usually sink. This works for cucumber too.
Alternatively you can buy lettuce clips from your lfs which you could use to
hold it at the bottom, or small lead weights which you could thread through
the vegetable.
Mel.

"Tim Neobard" wrote in message
...
My LFS suggested that to deter GF attacks on my plants, I put a hunk of
courgette (zucchini to the US?) in. So far, it seems to work well (the
fish
seem to enjoy the change), however the LFS's courgette was sunk, mine
floats. Although this is OK for my GF, they enjoy attacking the moving
targets (pushed by the waterfilter) the ground feeders aren't attempting
to
surface (supprisingly) Any ideas?