Mass Suicide!

[Themuleous]

Hi All,

Had a bit of a disaster. I've been running a planted nano tank since March and I've had 12 dwarf rasboras in there for the last few months. Then I noticed LFS has some in so I decided to get a bunch load more. All well and good after the initially day. I get home this eve (2nd day after being added) to find 6, yes 6! dry as a crisp on the desk next to the tank! Clean those up and have tea, during which another 6 decided to follow suit! So a full 12 have committed suicide, and that just so happens to be the number I added to the tank on Monday. Not best pleased.

Just wondering if anyone has any bright ideas at to why?

Tank stats

Size - 24lt
GH - 6
KH - 6
pH - 6.4ish (i bring it down from 7.4 using CO2)
Filter - Eheim classic 2211


What is strange is that the initial fish were fine for months, only had deaths since adding some more. My only thoughts are that it could be a drop in pH from the shop to home, not sure what the shop run their tanks at. Or i did to a 75% water change 24hrs after being added, could that have upset them? Just seems strange that it didn't happen immediately after adding them.

Any thoughts would be very much appreciated, thinking I might have to give up on this species, which would be a shame as I love them due to their small but colourful size.

Thanks

Sam

 

[WILDER]

I would go with ph ask the lfs what ph they kept them in.
A big mistake to do such a large water change so soon.
So according to what i've read only the new fish have jumped out of the tank.

 

[zoekin8yg]

Ive got a lid on all mine to stop jumpers

are they prone to jumping? I guess if the other ones didnt then maybe it was a problem

 

[Mr Miagi]

I think its more likely the addition of the new dwarf harlequins re-structured their hirachy and they then started to harass each other, causing fellow lemmings to jump for "freedom" or carpet surf as its better known. A change in water conditions could have resulted in them becoming less coloured or distressed, but I cant think of one instance where a fish jumps from water because of it. In marine aquaria its well known some skitish fish jump when startled or harrassed by other boistrous fish.

The fact that this never happened before you introduced new fish strenthens the argument, because surely over the time youve had the initial 12 dwarf harlequins, your parameters have shifted.

 

[lElxNoFx]

im no expert on the matter, but could it be your increased bio load on the filter? that couldnt handle it.

 

[Themuleous]

Thanks for the responses people. The fish aren't known to jump that I know of. Think I was silly in adding them and then doing the water change, think thats what did it.

Sam