New tank blues--dying fish

[imw]

as per Byron's input. I had a similar issue and lost 12 penguin Tetras. Bin the wood, run some carbon and do a 90% water change worked for me - no more fish were added for 2 weeks by me. Since then (all good).

HTH

 

[Byron]

If the fish deaths do not continue, as it seems they have not, then there is not much doubt but that the fungus on the wood was responsible. You cannot somehow remove this, it is in the wood. Throw it out.