Feeding Clown Loaches cucumber

I've read a lot about Clown Loaches enjoying cucumber occassionally as a
treat but couldn't figure out how to get it to sink. Then yesterday hit on
the idea of plant weights. So I carefully inserted a strip of plant weight
into a chunk of cucumber and after making sure there were no sharp edges
dropped it into the tank at feed time last night.

At first the Clowns didn't touch it and just swam around searching for their
usual evening treat (varies from Sinking tablets, Algae wafers or Red
Mosquito Larvae). Then my male Gourami found the cucumber and started
tucking in. The Clowns weren't far behind....This morning they are swimming
through the hole they have created and most of it (bar the green skin) has
gone....and still tucking in to what is left.

Couple of questions he-

1. How often should I provide this type of treat and how long should I leave
it in the water?
2. Any other ideas of what I can give them all to provide a variation in
their diet? (I'd get bored on just flakes every day)

Thanks
Gill