A bit surprised there weren't many posts about this,
After many years I'm thinking about keeping an aquarium (again). It
must be a real small one (6 gal) and if I can help it I'm going to be a
good (cheap) citizen and save energy by not heating it. There's also
the problem that heaters for such small aquariums are rare (but
possible to find). In fact I only remember seeing them sold commonly in
Japan, where people live in cramped apartments and probably keep tiny
aquariums too.
My room gets as cold as about 10 deg. C in winter when no one's around
and the heating is off. Unfortunately I understand that this can cause
large heat fluctuations which fish don't really survive? Except perhaps
for a few desert species that have to put up with the same in nature?
But they're far too exotic and hard to find.
Brings me onto the topic about what to keep in such a setup if it's
ok--of commonly available stuff, only goldfish take such low
temperature (if it's not too sudden) but they grow far too big for a
tiny aquarium. Plants are less of a problem, I'd decide on hornwort
which takes low temperatures but has to be pruned rather often in such
a small tank.

Seb

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