Mass Death Overnight

[Philuk]

Overnight I have had a mass death in the tank, 14 have died and for no reason, only thing that has changed was I put a new heater in there yesterday, the thermometer says the temp is 24-25 degrees c so I just dunno whats happened, the ones who are left have got there tail fins clamped together .

tank has been running for months with no issues. The water felt slightly warmer than it should but nothing excessive really, i used filter media from an old tank that i took down. its only a 15L tank so anything that goes a bit wrong goes wrong faster in it i understand that.
Nothing has been sprayed in or near it.
Changed the heater because the old one crapped out. temp dropped to about 19Degrees and all i can think is the change in temperature must of done it. Ammonia was 0 nitrates were up slightly but nothing massive. did a water change this morning in case but i dont hold out much hope for em. i turned the heater down a bit aswell just incase it was that! Bit gutted really. The tank was slightly overstocked but it was more of a growing on tank which would of let the fish go into my 160L which is next to it! BUM! is all i can think!

Any ideas?

 

[Rummynose]

Sorry about your fish!
It's good that you did the water change. How much of it did you change? Have you checked nitrAte (and nitrIte)?
But I too think it may have been the sudden higher tepmerature that did it!!!

 

[afremont]

Nothing has been sprayed in or near it.
Changed the heater because the old one crapped out. temp dropped to about 19Degrees and all i can think is the change in temperature must of done it.

Did you clean the heater before using it? Maybe their was some residual oil on the heater itself. Was it in a sealed package, if not maybe the store sprayed it with a few things over time. Outside of that, the temp swing seems to be the most likely cause. OTOH, it also seems like they would have been showing signs earlier if that was it. Is there any kind of residue on the surface of the water?

 

[FarmboyUK]

5 or 6 degrees is quite a big change over night. It would seem the temperature is the culprit however make sure you get some fresh water in there and clean off the filter before restocking incase it was contaminants

 

[Liam2368]

what's your water stats? am i reading that correctly you had 14+ fish in a 15l?

 

[Prime Ordeal]

what's your water stats? am i reading that correctly you had 14+ fish in a 15l?

My thought exactly!

 

[Philuk]

yea but they were at biggest endlers, good water changes and most of were due to go into the bigger 160l tank next to them. i got most of em about a week ago but they were just way to small to go ion so put em in the smaller one to grow them on a bit.

 

[Philuk]

Also, when i woke up and saw the death i got rid of the fish and tested the water

ammonia was 0ppm
nitrite was 0ppm
nitrate was 25ppm

did was 30% ish water change and thats it till now.

 

[Rummynose]

Quite possibly they could have been infected with something when you got them, good thing you had them quarantined!

 

[gobykilliefish7]

do they have clear accses to air i had a massive disastaer last year lost 30 odd and the was no acces to air


hope i could help


cheers

 

[Philuk]

yup there is a small airstone running aswell. all i can think is the heater