My understanding of goitre is that its under the gill plate and as its grows
it actually lifts the gill plate higher and higher. When you look at the
fish headfirst, you can plainly see that the gill plate is really out of
place. The problem I had with them is what you have explained that being a
whitish cream "bulbous" growth that eventually covers their mouth or sort of
grows on the lower side of the throat?
One of the easy way to add iodine is to use iodised salt!
Adrian.
Adrian R. Tappin
"Home of the Rainbowfish"
http://www.ecn.net.au/~atappin/home.htm