What is the best way to keep my fishes from dying?
Perform regular water changes, do not overcrowd, overfeed, or overmedicate, add compatible fish only, use good water (RO), and maintenance the filters regularly, leads most people to have great luck but still could lose a fish every once in awhile. Realize that certain species of fish/invertebrates have short life spans (sometimes a few years, or even months) and death sometimes is inevitable. If you wish that this is not a regular occurrence, take care of your aquarium and add specimens with longer life spans.