I started with 5 blue reef chromis, one just disappeared one day. Then from the four two jumped over board over a few months time. That left two which lived happily for almost a year, they even bred but I didnt get any babies even though I removed the eggs to another tank. Then I accidentally overdosed some flatworm exit and lost the last two. It took almost 2 years to get to 0 chromis which I dont think is horrible and I bet the last two would have been fine without me killing them.