3 dead goldfish in a week

[crumbedfish]

Hi I have just joined this forum to get some help. We bought 6 goldfish two weeks ago set up there tank and everything has been fine. But in the last 5 days 3 fish have died. There was no sign of disease so I am not sure what is going on.

One fish disappeared, we think he may have been eaten, another fish was dead on the bottom and as I type another fish is slowly dying. He is the largest fish in the tank. He is currently lying amongst the live weed, his mouth is opening and closing but he is not swimming.

What could be the problem, should I do a water test and see if the pH level is wrong? Should I dispose of the fish that is I think dying incase the other fish get infected? The other three goldfish are fine and swimming around happy.

PLEASE HELP.......

[Justikanz]

Hi, welcome to AQ! Give us more information, things like size of tank, water temperature, age of setup, types of substrates, filtration, plants list, tank mates list etc... We could help a lot better with more information...

[crumbedfish]

Size of tank is about 250ltrs, just over 3 foot long. I am not sure of the temperature of the water. We had the tank set up for nearly three weeks. The filter I am using is a submersible filter boyuauquarium brand. I have a few live weed of not sure of name starts with an E. I have two golden snails in there aswell. For ornaments I have a sunken boat and a chest that opens up with air bubbles. Also there is a bubble thing at the along the back of the tank for more air. I have one goldfish left and two black mores. They are about 4-7cm in lenghth.

I hope this infomation helps.