cultivating live silver sides as feeder fish

i have a 20 gallon s/w tank with a Green BTA that I have fed various foods to and from my understanding live foods such as silversides can be benificial to them. I have a 5 gallon tank as well with things from the long island sound including snails, hermit crabs, a quarter sized horshoe crab, whelk snail, and silversides that has been up and running successfully for months with just purely naturally taken things. the silversides are doing great in the tank and i was wondering if i caught silversides and acclimated them to the higher temperature etc if they could be used to feed the anemone and soon other fish that i will be putting into the 55 gallon i am working on. Looking for thoughts and opinions, i understand the whole idea of not introducing fish to a tank immediately as to make sure they are not infected with anything so i would probably be keeping an eye on them for a month or two before even thinking about feeding it to my inhabitants