bummer man, what type of set up did you have running. I have some killis that I personally collected in an inland bay in my tank. In the past I had creek chubs, they were pretty cool. They even survived with oscars, which is pretty impressive.
You don't need to collect them yourself. Just find somebody who does it for you and sells them legally. Shouldn't be too hard. But other than that I think zebra danio and white clouds are your only choices.