Ponds and tropical fish

I've been giving some my tropical fish a summer vacation in outdoor ponds
for several years now. This is a brief summary of the 2005 results.

The fish were put in the ponds in the middle of June and removed in the
middle of September. I try to wait until the pond temps are above 70 before
I add the fish and remove them before the temp goes much below 70.

This year I put Black Ruby Barbs, Tiger Barbs, Butterfly goodeids (Ameca
splendens), Giant danios, Electric Blues (Sciaenochromis fryeri), Red
Empress (Protomelas taeniolatus), Midnight peacocks (Aulonocara hueseri),
Pseudotropheus flavus, Rainbow cichlids, Bahia Red Geophagus, and a
Cichlasoma nicaraguense into the ponds.

When I caught the fish to return them to the aquariums there were Black ruby
barb, Tiger barb, and Red empress, and rainbow cichlid fry and the Red
empress, electric blue and P. flavus females were holding fry. The electric
blue female released her fry the next day and the other two less than a week
later.

For reference I'm located in south central Indiana USA. This summer there
were a number of days with 90+ temps. The surface of pond containing most of
the fry and the African cichlids was about 90% covered with water lettuce
and water hyacinths.

If you have questions about trying tropical fish in ponds, I'll be happy to
share my experiences.