I googled hith..thanks!! I never knew such a thing existed!! He was stressed as I had just taken out of the 55 put into a 29 then back into the 55 the next day after I redid the tank...thanks for the idea.
my next question is that I am down to three corys now...I've been told they need 5 or more to be happy...I bought 5 but one died during transport from the lfs (was dead when I got home) and now this one...I'm down to three. Should I buy more?
are there angel fish in the tank. Hole in head is very common in angel fish usually genetic I keep 48 varieties of cories but have never seen this before. Sorry to hear for the loss were they tank raised or wild caught.