I've got 2 sons - 4 years and 5 months. I thought a fish tank would be fun and educational for them. My wife has been against the added life complication, but somebody gave me a tank for free and I just brought it home one day, so now we have a 10 gallon fish tank. I have no idea what I'm doing with it. I didn't have a place for it, so I filled it up with water and stuck it out on the deck to cycle for awhile and let the chlorine out or whatever. I knew better than to put fish in fresh tap water. After a week or so, my wife warms up to the idea and finds a spot in the dining room and announces we are going to go buy some fish. So we go and get a couple of goldfish and some fish food. The clerk said we also needed a heater and some biological additive, so we picked that up too. The red capped one did okay. The fantail wasn't really eating and my son noted that it only had 1 mouth. He thought the gills were extra mouths and fish are supposed to have 3 mouths. That was yesterday. This morning, we wake up and the fantail is dead, but because it was stuck to the pump inlet, it still sort of looked alive. So I spent the day today reading all about fish and aquarium and going to stores. Ammonia tested high. I think my used tank was not that clean and I started off with bad water. So I changed the water a few times and added more bacteria and tap water conditioner and electrolytes and an air pump. Probably not the best way to do it, but I had to get the ammonia level down so I could get another fantail in there before my son comes home from school. I also took out the 78 degree heater, because that seems pointless based on what I've read. If anything, it will just reduce the amount of oxygen in the water. And that's about where I'm at with my new aquarium hobby.