2~3 weeks ago my 10 gallon with my 3 girls in it had its first problem.
One of my girls got sick and died in the course of 3-4 days. I didn't know what it was but she floated to the bottom and had trouble swimming up.
Now ive dealt with Dropsy before and it looked vary familiar, but it happened a lot quicker than I expected.
Once she was gone not a day later both of the others were sick, and now the last girl is getting ready to leave me :/
My question is, what exactly do I need to do to prepare the tank for new fish and not have them get sick?
The water parameters are perfect and the tank was well planted, heated (100w at 80 degrees) and cycled (fake plants).
Do I need to drain it and clean everything? if so what do I do about the sand? I don't really want to have to buy new sand :/