Hi,
Some strange things going on in my tank today, husband got up and noticed a harlequin dead, turned the light on (we often don't have the light on now as we find the algae goes crazy if the light is on too much) to discover the water very cloudy. The water has always been fine, we've never had any problems before and haven't recently added any new fish.
I tested the water while he did an emergency 60% water change (in 3 stages) and as he was doing this some of my pink neons and harlequins were gasping at the surface and dying as he was doing it. Before change Water was Ammonia 0, Nitrite 1.0, Nitrate 40-80, after first bucket of water replaced Amm 0, Nitrite 0.50, Nitrate 10, after 3rd bucket change the water looked better for a bit but has since gone very cloudy again, Amm 0, Nitrite 0.25, Nitrate 10.
We've also removed the rock and washed it out in case there were any dead fish lurking in there (1 pink neon disappeared mysteriously a while ago) but it was empty.
Any ideas? The only thing my hubby thought was that we had bought a new 'Supa Natural Fern' (given up on real plants as they don't live long) and had put it in the tank, forgetting to rinse it first, could that have done something to the water?
We've googled it and amongst other things read not to change too much of the water so have now stopped the water changes in case we are making it worse? Remaining fish not showing any signs of suffering at the moment but the water has looked cloudy for hours now, it's very odd. We have gravel as substrate, 200L filter, tank as been running no problems for a good few years.
Any help or suggestions would be great, thank you
Zoe
(60L tank, 1 harlequin, 3 pink neons, 2 cardinal tetras, 2 Pentazona Barbs, 1 small platy, 1 Oto)