I have found that my dollar sunfish are a lot less shy when stocked with small schooling "dither" fish. I have been doing some experiments with low-cost, captive-bred, temperate water pet store buys before going through the trouble and expense of adding more desirable natives.
When I first started out, I kept the dollar suns with some fathead minnows. This was a stupid, amateur mistake. Fatheads are nest-builders, like the dollars, and they both occupy the same part of the water column. Ended up with a lot of fatheads on my floor. Some even jumped into other nearby aquariums. My dollars were all juveniles at the time, so none of them were large enough to eat the fatheads.
After the fatheads, I wanted to buy some attractive but somewhat expensive captive-bred top minnows, but thought I'd do a size check with zebra danios first. Very glad I did. The zebra danios (1") were excellent dither fish, keeping the dollar suns active and feeling safe. But then they all got eaten. Oh well
Now I have some giant danios. They're much too large to swallow (about 2"), but in the first week two were apparently bitten to death. It's been about two months now and the remaining school of 5 seems to be getting along well.
Sometime this summer, I would like to give away the giant danios and replace them with a native schooling fish. Aesthetically, the giant danios are larger than what I would like (2"). They distract from the dollar suns, which are supposed to be the focus of the tank. On the other end of the spectrum, the zebra danios (1") were too small to be compatible with my dollar suns. I'm looking for something in between. I believe that a fish that is 1", but wider than a zebra danio, would probably not fit in the mouths of my dollar suns.
Does anyone have any recommendations?