Fish in a barrel

Last year, I built two rain barrels out of discarded 55 gallon plastic barrels and put them by the garage.  This year we wanted to add two more to the house but had a problem.  We have gutters on the new garage, but not on the house.

All the rain barrels I'd seen (and consequently built) had small, downspout-sized holes at the tops covered with screens to prevent the gathered water from becoming a mosquito breeding ground, but we needed to place open-top barrels at two corners of our house in order to gather the torrents sliding off our roof.  And we needed to do this without promoting mosquito growth.

The answer?  Goldfish.  My friend told me that she puts three or four feeder goldfish in her open-top barrels every year.  They eat the mosquito larvae, algae, and any other bugs that find their way into the water.  The volume of water protects the fish from getting too hot in the summer, and, theoretically, they might even survive the winter if you leave them there (my friend takes hers to her parents' heated koi pond).

So we gave it a try.  We bought twelve goldfish, six for each barrel, assuming a 50% mortality rate.  All were happy for about three days, but we reached 100% mortality about one week later.  What was wrong?  We don't know.

So we tried again. This time, we lost all the fish in one barrel, but three survived in the other.  Those three have been going strong, and I am loathe to let Sam empty the barrel for the winter.  It might be fun to see if they can make it through to the spring!