Dying Fish - Is The Tank Cycled?

[fergalthefish]

my sis has a 28litre tank. igave her a very well matured sponge from my filter to put in her filter.then she put in a betta and 3 corys.i cory has since died and another is on its way out. she's done a water change a little while ago. i thought putting my matured filter in would cycle the tank but it would seem not?? any ideas??

 

[Callum]

You could test to see if its cycled, (nitrate, nitrite, ammonia), Maybe the fish were ill when she purchased them?

 

[fergalthefish]

true but that would be extreme bad luck i think. don't have a test kit at the mo so any emergency help appreciated.

 

[WILDER]

Its hard to say whats going off without water stats as is the first thing to rule out.
I would take a sample of your tank water to the lfs and tell them to write the readings down for you.
I would also advise investing in a liquids masterkit of your own.

For now I would recommend a water change till you get your water tested.