What the..

Really?! I purchased a school of 5 from liveaquaria.com, which usually gives some basic information about what it is you're about to buy (or not buy). It didn't mention anything about that, or may have thought twice about it. So there's a chance I'll lose more? There's one more that's a little smaller and slower swimming than the other three.

 

yep, I bought 4 chromis and they reduced their "school" to 3. Seems they like odd numbers from what I have read. search for "chromis pecking order"
or something like that.. it should explain it all.

 

It's very possible that they are "thinning out" the shoal. Watch the smallest for a few days, he may be the next one to disappear. And Chromis don't actually school. They shoal. Its a small but subtle difference. Schooling is a social activity. Shoaling is a defense mechanism to make them look bigger to a predator.

 

Good to know, thanks folks.

 

I found him! He was in the first section of my sump, lucky not to have been sucked into the mag 9.5 skimmer pump. I had to take a lot of stuff apart to save that little fish, but it was worth it.

 

Wooo so he got thru the overflow? wow... But with the hermits, you might could have a mantis?

 

So check this out, the latest issue (may/june) of Coral magazine has a great article on hermit crabs. Towards the end of the article it reads:

"Protection from a shell can fall short, and hermit crabs themselves sometimes are victims of predation. Many fishes, such as wrasses, possess strong pharyngeal jaws with which they crush the shells of small snails and hermits. Longnose Hawkfish are especially efficient predators of small hermit crabs, first tipping them over and then grasping and pulling them from their shells".

Matthew L. Wittenrich - Coral Magazine May/June 2009