In rec.aquaria.freshwater.cichlids John McCormick wrote:
Hi Cichlidiot,
I have found that it is much safer to let the fish go without food for
several days rather than rely on someone unaccustomed to looking after fish.
Having said that if it was caused by your filter dying combined with the
high temps then the fish would have died with no one looking after them
also.
Either way it is not good to return home and find them as you did.

Pretty sure it was the temps and not the food. May not have even been the
filter. I found out after further investigating that she had not turned on
the AC Tuesday evening either. Nor did she open windows or turn on fans to
bring in the cool night air. So basically, it sounds like the fish tank
room was an oven (temperature wise) from Tuesday until I got home Weds
evening at 11pm. The larger cyprichromis fish had been dead long enough
for their eyes to go white and fungus to start growing. The smaller fish
that survived the temps I think were killed off by the ammonia caused from
the dead cyps and the food. Their gills were bright red, which I believe
is what happens with ammonia poisoning. How my roommate could have failed
to notice 8 floating dead fish and kept dumping in the food without
calling me is beyond me. The stench in the tank makes me pretty sure that
these fish were dead before Weds's feeding. Can't see how so much stink
could have occured in just a few hours even given the temps.

The food I vaccuumed off the gravel was not fungused, so I think it was
from Weds afternoon feeding. I'm beginning to think that most of the fish
were already dead then and the non-eaten food and/or dead fish and/or
snails is what clogged the filter and made it stop. I have had problems in
the past with the snails forming a mass on the intake grill and then
getting mulm stuck between the snails so that filter flow is reduced.
Never had it completely cut off filter flow, but then I've always noticed
when the flow is reduced.