Fish Dying -- Help!

[AlxBlack17]

I just set up my old aquarium thats been sitting dry for a few years. We let it cycle empty for a day and bought three fish (2 mollies and a green spotted puffer) on Sunday. On Tuesday, One molly was dead and there were 6 babies swimming around. We bought them a little breeder net and all seemed fine. This morning (Wednesday) when I get up, the puffer, the remaining adult molly and all but one of the babies were all dead.

I've read that both mollies and puffers do better in brackish water, but I'm pretty sure that the problem wasn't just that it was fresh water since I've had mollies do perfectly fine in fresh water many times before. We did find that our city's tap water is high in both selenium and nitrates. Could this be what is killing the fish? If so, how do we correct the problem?

Thanks

 

[st24rsap]

the problem is that the tank wasnt cycled, this can take weeks not just a day and with fish in it requires daily water changes and constant monitoring with a liquid test kit of the ammonia, nitrite and nitrate levels. you need to research fishless or fish in cycling on this forum and start again im afraid

 

[Faythee]

Start here:

http/www.fishforums.net/content/New-to-t...ease-Read-Here/