Buying a live rock infested with eggs of these worms.
they eat everything and anything ! corals, fish, and polyps too.
Very nasty.
Lesson learned:
Live rock Never again!

Next tank will be started with DRY Eco rock only !
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http://i381.photobucket.com/albums/o...h_MVI_0616.jpg
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http://i381.photobucket.com/albums/o...6/IMG_0611.jpg
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http://i381.photobucket.com/albums/o...6/IMG_0614.jpg
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http://i381.photobucket.com/albums/o...6/IMG_0609.jpg

I have two....both powder blue tangs.....Ive tried twice and both times they only lasted a few weeks.....still dont know why, to this day...

worst purchase
 

about 14 years ago, put 4 camel shrimp into my 90 gallon lps dominated reef. Damn shrimps ate everything. Took me months to catch them. We didn't know any better at that time, as there wasn't much info on them.

Yep. But generally speaking it sucks whenever you buy something new (fish or coral) and it dies right away.

Powder blue tang....Died yesterday. Lasted about 2 months:cry:

Probably was cyanide caught. Was he eating well but just looked skinny?

worse buy ever
 

any critter that didn't last a week after i bought it.

It was eating, but was skinny. I will not add any other tangs to the tank. My large hippo runs the show.

Copperband Butterfly. Not disappointment in the fish, it's such a beautiful critter, but disappointment in my stupidity for purchasing one prior to proper research. I know there are a good number of success stories with these, but if you look at the recent poll related to Copperbands, the statistics are a good indication that these guys are best left in the ocean. It was quite tough watching my specimen slowly starve to death.

My most disappointing experience, 2 beautiful elegance corals. One had pink tones, the other greens. Absolutely stunning specimens. Both did great in QT tank, so we put them in the 180g after a week and a half. Two to three weeks later the green one started to deteriorate, and unfortunately whatever it was seemed to be contagious because about 2 weeks later the same happened to the pink one. Not sure why it happened, we had not had any issues with any other corals. They just slowly deteriorated. Very upsetting experience, not to mention a little pricey.