Thanks all, but I didn't really post here to get kudos on the fish but rather with the hopes that whatever I'm doing right can be used by someone else. My pond evolves every year. Each year it is interesting to see what happens next.
Regarding the cement houses, might be better just to heat it all up and melt the foam out. If you use the styrene bead foam it will burn out quite easily with a little fire. Otherwise me thinks the gasoline will soak into the cement and polute the pond somewhat.
