Hi first post (well second as I replied to a post on my way to make this),
I have a 75 litre tank with rocks, driftwood, lots of plants, 4 freshwater mussels, 3 "goldfish" (sorry not sure of the exact type - just plain everyday goldfish), 4 borneo suckers a ramshorn (I think) snail and a koura...
these guys were all living happily for the last few months ... I had a problem with green water which I believe was due to the rocks and driftwood that I added. I was changing 20% of the water every few days (sometimes more). The days I changed more Robert (Cray - my koura) seemed to come out and play a lot more ...
anyway on Saturday I noticed around lunchtime that he was out of his cave sitting next to a piece of driftwood which was very odd - I went out for a few hours and when I returned much to my dismay he was in the same spot, only upside down and motionless. I immediately took him out and placed him into a bowl which I use as a temp spot for fish plants etc hoping he might miraculously spring back to life but alas he didn't
I went and got another 2 koura (both found under the same rock) and took the opportunity to drain my tank completely so I could better arrange the rocks for both the koura and the borneo suckers. This was yesterday - I wake up this morning and both koura are dead and so are 2 of the borneos - I cannot see the other 2 borneos so am not sure whether they are dead too
I have no idea what has caused this. I have done some tests on the water:
ph = 7
nitrate was between 5-10 - say 8ish
ammonia = 0
n02 was approx 0.5
water temp was around 21 at change - my apartment is warm so my "coldwater" tank isn't all that cold - was around 23ish before the change
there is a cocoon the top glass (out of the water) which I believe is just from the snail and I doubt it would have any ill affect (other than the influx of baby snails soon to come)
my fish tank is my new hobby and I feel terrible that my lack of knowledge in this area has possibly been the cause of all this death