A bit more on leaving your fish home alone. Harro is right about it being
safe to leave well grown fish for lengthy periods. I've gone well past the
two weeks he mentions, BUT, I'm fairly careful about when I do that.
The key point is water temperature. The only times I've successfully left
my fish to look after themselves for extended periods is in the cooler
A lot of us stick to all the advice handed out about keeping our fish in
supposedly ideal conditions in the mid twenties Celsius, ( 60s 70s F),
without considering the conditions the fish experience naturally in their
wild environment. Let me assure you that many of the streams rainbows live
in are decidedly cool when we go collecting in winter. ( Incidentally I
should mention for you North Americans that when we talk winter think the
Florida end in your part of the world as an equivalent. )
In the wild rainbows not only live in some cooler water in winter, but as
Harro said, face a vastly reduced supply of food at that time too. In
Northern Australia and New Guinea where all the rainbows are found, we have
a very hot wet summer, and cooler dry winters.
The dry winters mean much less to no flow in streams, and less food
But with lower water temperatures the fish are less active, burn up less
fuel, and therefore need less food.
So we finally come to the real business. When you want to go away and leave
your fish for a week or three - Bring on an artificial dry cool winter in
their tanks !
Most Australian fish will survive quite well in mid teen temperatures C (
around 60 F) and will demand far less feed at that temperature. Going much
lower than that for some of the coastal tropical species could be pushing
your luck a bit as far as susceptibility to disease goes.
Lower the temperature before you go away if you can. You will have to think
that out for yourself allowing for your weather at the time. If its really
frigid and your heaters won't turn down far enough, maybe put them on
timers, switched on for a few hours ?
Just to go back to the start where I said that success in leaving fish
depends on timing, I certainly could not go away at the moment. We are
having a sweltering spell and my unheated tanks are just on 30C. At the
moment I have fish which are continually hungry.