dead fish

[timb]

I bought a second hand biorb 45 litres with some water left in at the bottom. The filter is also old.
There is sludge under the rocks and half of the fish have died in the 3 weeks since setting it up.
Should I remove all the water and start again thanks. The water apart from this is clean.

 

[CaptainBarnicles]

Hello

Erm....we probably need some more information of that's OK?

How did you receive the tank? Did you add the fish or did they come with the tank? Do you know about cycling and water changes? Can you please post some photos of the whole tank so we're better clued up on how we can help

 

[Fishies4Ever]

I am sorry for the loss of some of your fish. Could you put up a picture of your tank? Do you know about cycling a tank like captain barnacles said? How many gallons is the little tank? What fish do you have in there and how many?

 

[timb]

Thanks have replaced one third of water so far. Bought all the fish new.

 

[CaptainBarnicles]

OK, I can see that you're in a bit of a pickle. Unfortunately I'm about to hit the hay, but there's a wealth of knowledge around the forum and I'm sure someone will be on their way to help you shortly. In the meantime please explore and make use of this thread
Thread 'Cycle Your Tank! A Complete Guide For Beginners' https://www.fishforums.net/threads/cycle-your-tank-a-complete-guide-for-beginners.475055/

 

[Fishies4Ever]

What kind of fish are in there and how many of each kind?

 

[Colin_T]

Test the tank and tap water for ammonia, nitrite, nitrate and pH. Post results in numbers here.

Reduce feeding to 2-3 times a week until the filter has cycled. The fish won't starve.

Do a 75% water change and gravel clean the substrate every day for the next 2 weeks. Then do a 75% water change 4-8 hours after you feed the fish. In a month's time when the filter has finished cycling (developing beneficial bacteria) you can feed once a day and do a 75% water change and gravel clean the substrate once a week.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.

Post pictures of the remaining fish so we can check them for diseases.

 

[BettaFishGirl]

Yes, we need the full stocking list of the tank, including all fish, shrimp, snails, or any other inhabitants.
Make sure to test your water ASAP. If you don't already have a testing kit go to your LFS (Local fish store) and they usually test for free. Or you can buy a testing kit for yourself. The best is the API master liquid test kit, it has over 800 tests, and the strips aren't usually accurate.
Did you cycle your tank before or do a fish-in cycle?