Green Chromis continuing to die off

Three or four months ago I started with 7 green chromis. I am now down to two. One just disappeared into teh rock Friday. Yesterday morning my cleanup crew had him for breakfast. My water parms are OK. Zero ammonia, zero nitite, nitrate less than 20, etc etc so I don't know what could be killing them off. It always seems to be the smallest one who goes. They all seem compatible in the tank, occasionally my clowns will take a run at them but it does not seem in an agressive manner and the chromis don't exactly run and hide. Has anyone else experienced anything similar?

 

Same thing happend to me about 6 months ago all my other fish were fine but the Chromis just started to die one by one. Never figured out why.

 

Me too, I had three and just found the last one dead yesterday. All parms are good.

 

I love green chromis and have always tried to keep them in sizable groups... In my 180 I had 12 that is now 5. Everytime I try to add more it always ends up at 5.

There is a few reasons for this.
Chromis are terrible shippers.... If you buy them from a store they are most likely stressed from transport, if you order them on line well, shipping them to your house will stress them.
They form a strong hierchy and will constantly nip at each other... Weakest typically gets beat enough that he can't eat or just withers away. The next weakest then takes his spot on the totem pole. I real reefs there is 10,000 of them not ten so the badgering is spread on a much larger base.
Lastly which is very often the case....chromis like other planktivores have a HUGE appetite, and fast metabalism. They literally need to be fed all day long. On the reef all they do is eat and hide, eat and hide all day.
In a tank that is fed once or maybe twice a day it is hard for chromis to keep enough "weight" on. Other fish will graze on algae of copepods/amphipods but not chromis. They need zooplankton in the water column, and unless the tank is producing that itself, a tank with chromis needs to be fed...alot!!

Frozen fish eggs work great for chromis.
Good luck and just keep feeding!

 

Thanks Dr Fragenstein, very insightful! My only problem is that I was fighting the nitrate problem and have decreased feeding to once everytwo or three days alternating between mysis shrimp, flakes, garlic coated pellets plus seaweed every other day. I did notice that the chromis were the only other seaweed feeders other than my tang. i did recently purchase a new skimmer (remora c) and a new nitrate test kit seems to indciate that my old one was testing high. So maybe I will increase feeding a bit and keep my fingers crossed.

 

Hello, while Frags' post could be right on, I have not researched his hypothesis enough to verify it. What I have found is this; Green chromis in particular as Frag stated have the "pecking" order thing down pat. Usually they school in odd numbers for reasons unknown. If you add 5 to your tank they kill off the weakest, that leaves 4 and that is unacceptable to them and they kill the next weakest to get an odd number again. I have had these three in my tank for quite awhile now. I started with 5 and it quickly became 3, I added 3 more to test the theory and soon the 3 newest ones were knocked off (I knew they were new, smaller). I did a little research and came to the conclusion that if fish from two or more schools get mixed together, one school (group) will dominate. In the LFS we have no idea how many parts of different schools are mixed together. Feeding never seemed to be a factor for survival, however in my tank I do add Arctipods (Reef Nutrition) and Reef Plus (Amino acid formula) so my fish are getting a lot of nutrition.
I will be curios as to see if you get down to one as I am surprised the third one was killed. What else is in the tank (livestock wise)?

 

I must be lucky or something!

I have had 10 in my tank for a few years now. They lay eggs all of the time and are always schooling as well. It could be that they are pretty much the dominant fish in the tank as I have all peaceful tank mates. There is definitely a pecking order but ther never attack each other except to keep away from their eggs.

 

same thing w/me, with green chromis started w/5 went to 3 added 2 more back to 3 in a matter of days leave well enough alone