Koi Fish Shock?

[dohntaut]

I just got a new tank, or well a used tank. It was given to us by a family friend, it is about an 80 gallon with 2 pretty big koi fish and 5 other gold fish, they were feeder fish that just grew over time. i am well aware that the tank is too small to house all of the fish. But for the time being, this is my first cold water tank, and i do not know where to begin.
I think it should be similar to tropical fish.

So to begin i think i made my first mistake by cleaning the tank and filter with tap water( everything was really dirty, a lot of sludge everywhere) since i didn't have much tank water from transporting the fish. I guess this may un-cycle the filter?

The next thing is that i think that i may have shocked the fish. I filled it halfway with water from my sink, then put the fish in the bags to acclimate them to the temperature. Then after i let them go, i filled the rest of the tank with water from my garden hose ( it was much faster) but i think that was a bad idea because i just realized that my garden hose water is much harder than my tap water. Now all the fish seem to be dieing, they kinda just stay on the bottom and dont move much, sometimes they might tip over a bit.

what should i do? should i drain some of the water and fill it back up with water from my tap, softer. i did use stress zyme and stress coat.
i feel like a fish murderer now, hopefully none of them do die.

 

[newtothis26]

hi there not really that clued up on cold water fish but i presume u put water declorinator in with the tap water as this might be a reason they are at the bottom what i would do is do a 50% waer change and this time add water declorinator to the water and use a kettle to boil water to get the correct temp to put back in the tank and see how they are after that

 

[fishnovice]

Coldwater fish need exactly the same care and treatment, including water changes, filtration and acclimatising as tropical. The only difference is no heater required. Goldfish are pretty tough as fish go so hopefu;;y yours will recover. Next time. make sure you match the water temp during changes and use dechlorinator. I find it better to fill tanks completely before adding fish as pouring in lots of water once they are in frightens and stresses them

 

[dipsydoodlenoodle]

Warm the tank up!

I had turning over from two of my fish; I just put them back in warmer water and they righted themselves and started breathing and swam away.