Many thanks to all for your comments and help. An update, now that I
have actually seen the fish...the redness is actually a largish lump
is just forward of the pectoral fin and only on the bottom; looks more
like a large hernia than anything else, and definitely not a skin-
disease type of thing. It's a bit smaller this morning since a 1/2
water change last evening, and the fish is perky and interested in the
(very little bit of) food we gave him.

"Benji" (we actually don't know the sex) is a 11-year-old feeder
goldfish, about 5 inches long, so a 5-gallon tank should be fine, no?
(No room for anything bigger anyway.) We have changed the water once
a month using our (very pure mountain) tap water that we have let sit
open for 2 days, stirring occasionally. We always keep a large carboy-
type jug of water sitting for fish change water and drinking water for
our two snakes.

The tank is not filtered, never in direct sun, and has no plants in
it. We have done a complete water change and tank/gravel scrub
monthly for years (putting the fish in a bucket of the "old" tank
water plus some new water), plus partial changes every so often when
too much food is accidentally fed. The fresh water is always the same
temperature as the tank--learned that lesson the hard way in my callow
yout'.

I will stop and get some antibiotics and salt today, and we will do
partial water changes weekly from now on...hopefully that will do the
trick. I have no idea what to do if the lump is eggs...yikes. Can
one massage them out?

Jeannie

P.S. I will say here that I am disappointed to see that this group is
like most other Usenet newsgroups--certain folks are so intent on
insulting each other that they waste time and bandwidth on off-topic
mud-throwing posts. Guess you can't get away from that anywhere!