Thanks for all the replies. It was useful information but, alas,
nature had other ideas. The eggs are gone and there's not a fry to
be seen. Maybe I'm not looking hard enough - I'll keep an eye on it.
Sadly, the pleco died, though I'm sure this is a coincidence.

Another, related question - I returned from a two week vacation on
Sunday to find these eggs. While I was gone, the furmace quit
working for three days, and I was told that the temp in the house
dropped to 42 degrees during that time. The tank's heater was
working, but I suspect it couldn't keep up with that. Also, my son
(the house sitter) told me that he forgot to feed the fish for two
days in a row last week. Perhaps this was partly to blame for the
pleco's demise. But, aside from that, I've been led to believe that
fish can be coaxed into laying eggs by adjusting their water
temperature and feeding patterns. Could this be one of the reasons
that the fish laid these eggs at this time?

In article ,
says...
Please excuse my ignorance, but I've got a question. I have a 46
gallon freshwater tank populated with a few Zebra Danios, Black Skirt
Mollies, some Albino Catfish, two Glass Catfish, a trio of non-
descript Catfish, and a giant Pleco (a fine looking fish, indeed!).
These have all been together for at least six months, a few as long
as six years (the pleco among the old timers). I recently noticed a
couple hundred or so white eggs, each about the size of the head of a
pin, attached to the glass, primarily, though not exclusively, in the
upper corners of the tank. Any idea which of these critters might be
responsible? Are they waiting to be fertilized or can I expect to
soon be overrun with one of the above mentioned fish? Is there
anything I should do to ensure their safety and/or viability? I
think it'd be fun to see hundreds of tasty morsels swimming around,
with perhaps a dozen or so growing to adulthood. Any thoughts and/or
suggestions would be appreciated.