New to the whole fish thing

[sadiekay215]

I was apparently deprived as a child, and never had fish growing up. I need as much help and advice as I can get.
So, my step uncle has had a tank, not sure how long. And he didn't want it in his room anymore, so we moved it to my room. He had two fish, I believe they were just plain goldfish. I cleaned the tank out (there was a nasty amount of poop in the bottom, I don't think he ever actually cleaned it ), and filled it with room temp. water, just like he told me to, and has before... About an hour later, both of the fish were dead. Within that hour, they were swimming upside down, and kind of floating to the top, but then they'd keep swimming, I thought they were just weird fish, and then they died. I don't know what I did wrong, or what I should do differently. I'm going to go buy new fish sometime this week, if I can figure out what to do right this time. Help, please?
It's a 10 gallon freshwater tank.

 

[jsodwi]

Do you have a heater and a filter? Temp should be 78-82 degrees. For tropical freshwater fish. You just can't fill up tank and throw fish in. The water needs to cycle do so e searching on this site there is a ton of info once the tank establishes itself, taking care of fish is quite enjoyable. Good luck

 

[cali~budfish]

Is it city water? You use a dechlorinator?

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[ElectricBlueSeanBurch]

Do you have a heater and a filter? Temp should be 78-82 degrees. For tropical freshwater fish. You just can't fill up tank and throw fish in. The water needs to cycle do so e searching on this site there is a ton of info once the tank establishes itself, taking care of fish is quite enjoyable. Good luck

He said his uncle had it setup for a long time, so I don't think NTS is the culprit.

Is it city water? You use a dechlorinator?

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This would be my guess as well

 

[Gill Blue]

I cleaned the tank out .

this could also have been why, or contributed to their deaths. did you use soap? soap kills fish. just a little residue can coat their gills and suffocate them.
did you clean everything? bacteria builds up on your surfaces - glass, gravel, decorations, insides of filter - that convert fish wastes to less toxic substances. if you cleaned all that off they'd poison themselves, just as you would if you were locked in an air tight room without a toilet. the same goes if you used bleach. if all that bacteria is gone you need to start over - figure 6-8 weeks before adding fish. you can buy that bacteria bottled, I've had good results with seachem stability and api quick start, and that will get things up and ready in about a week.

add to that, a 10 gallon is not big enough for even one goldfish, so they may have not been very healthy to start with, look up stunting.
with that size tank you want fish that won't get more than 2-3 inches, this should help with your fish choices. as mentioned, while golds don't need a heater, most tropicals will.
if you can find seachem safe, I'd recommend that for a dechloirinator.
go to the search in the upper right corner and start reading. cycling, nitrogen, ammonia, waste, biological filtration

 

[sadiekay215]

I did use soap, but only on the tank, not the filter or anything, and I made sure it was completely rinsed out. I just rinsed off the decorations that are in there and didn't wash the gravel at all, or the filter.
I'm not 100% sure they were goldfish, they were pretty small, maybe 2 inches long.
I am going to go to the pet store here shortly and I'll ask about the seachem, thanks for your help