I have 3 extremely skittish silver dollars in my 240. I know it's recommended to keep at least 5 but I've kept 3 in a 55 then 125 and they were fine so I am thinking the bigger tank is less cozy and a bigger group may be needed. What's the chance that 3 more sd will make a drastic change in behavior? My 3 are generic lfs sd, should I stick with the same type or will a mixed school still be calmer? The sd don't disturb my cichlids to much, they scatter to get out of the way but they really spook my datnoids so should I just get rid of them?