Don't want new fish to die

I've kept those before many times. I'm absolutely no expert in the matter, however.

I always kept mine in smaller bowls or small tanks designed for them rather than larger tanks. I did keep one in a larger aquarium once and it actually didn't fare well. Chaos (the fishie) stayed in one area and seemed very depressed most of them time and lived a very short little life.

There are small tanks designed for them available at most pet stores and even mass merchandisers like Walmart and Target.

I did find that using a water conditioner specific for those type of fish and a small light during the day made a huge difference on their general happiness and lifespan.