My mom recently restarted the 10-gallon tank I left behind when I moved and purchased an oranda for my little brother. The oranda itself was only a couple inches and we have had fish before, so my little brother knows how to acclimate it to the water.

However, after being very active and happy, it died over night. My little brother says that after feeding it some sinking pellets, it looked very lethargic. The water was not tested before my mom drained the tank, so I have no idea what the numbers could have been.

Is it possible to have an ammonia spike kill a goldfish on the first night? Or is it possible that something else got to the goldfish? I'm a little surprised that one oranda in 10-gallons can die so quickly. My little bro's a bit depressed. Any advice would be appreciated.

In the meantime, I'm asking my brother to purchase a master test kit to make sure from now on that the parameters are good. I hope things go better for him and my mom in the future.

I am sorry for your loss

Yes, ammonia in an uncycled tank can kill your fish overnight. Over feeding would make the problem worse. Many petshops will test your water for free so your mother could take a water sample to the store to confirm if the cause of death was ammonia.

I am soooo sorry. It is entirely possible that a combination of circumstances all played together to kill that poor little fish.

A fish that may have had some parasites or bacteria complications - just minor ones - added to the stress of going into a tank with a different temp, different pH, different..... everything could have just added up to too much stress and killed the poor little thing. It is also possible that the water was fouled by ammonia - yet another terrific stressor.....

A test kit is a GREAT suggestion. Helping your brother cycle the tank before getting a fish - perhaps by sharing some of your beneficial bacteria or by seeding his filter in your tank - will go a long way to helping him successfully keep fish. A cycled tank, a pH, kH, gH, and ammonia/nitrite/nitrate test will also help him to learn how to correctly match the water to the fish's needs.....

Tell him not to be too down hearted. Sometimes circumstances all conspire together to make the worst happen.