Fry Disaster!

[Plecc]

Hi guys,

I went to clean out my new 305 yesterday and found it full of BN pleco fry! (my 2nd batch in a month)
The first batch of fry (50-60) are about an inch in length are growing fast and all appear very healthy.
The only problem is my tank and filtration are at there limit trying to cope with the first batch of fry, as the second batch managed to almost all find there way into my filter i thought it would be a good idea to get them into another tank while i have them all in one place.
I decided to use a 25L storage box with a clip on lid, the box was new so i just thoroughly cleaned it with tap water.
I put in a small 25w heater, digital thermometer and an internal filter with a spray bar (to help aeration), all kit was cleaned with tap water apart from the filter which was cleaned using water from my main tank.
I then filled the 25L box with water from my main tank and filled the internal filter with matured media also from my main tank and a small upturned flower pot to give them somewhere to hide. (no substrate)
As i left them last nigh all appeared fine, the tank was holding a consistent 24 degrees, filter flow was not too strong for the size of the tank and the water was clear and well oxygenated. (i also decided not to feed them for the first day just while the new tank settles down)

So i come up to check on them today and the new tank looks like a scene from the apocalypse, all the fry have died and the top 1/3 of the tank is cloudy.
OMG what happened?
What did i do wrong?

They had the the same water and filter media from the larger tank that they were thriving in!
First thing i checked was the water conditions which all appear fine and exactly matched the larger tank that they came from yesterday.
The only variable that changed was light, but surely going from living in a pitch dark filter to a dully lit room cant shock them all to death! (or can it?)

Any info on what may have happened will be greatly appreciated.

Plecc.

 

[indigoj]

toxins from the plastic? heat fluctuating?

 

[Plecc]

The tank temp was being monitored by a digital thermometer which records max/min temps, through the night the tank only fluctuated by 0.4 of a degree.
You may be right about there being toxins in the plastic, although the plastic box i was using was meant for storing kids toys so i assumed this meant it would be play safe. The box is also transparent so there should be no dye's or pigments within the plastic.

 

[Alind]

That's very sad.
something was wrong from your side thats why of them died or else some of them would died.
was the idea of not feeding them right ?

 

[drobbyb]

Although the plastic was probably safe, we can't rule out any number of things that may have gotten into the box prior to you using it. If the filter was mature, and the temperature didn't spike too much (as it appears it didn't) everything should have been fine. The only part that I can see a catch with is the cloudy water. Usually that results from an under-performing or not cycled filter.

 

[Plecc]

drobbyb,
I think you may have it with the under-performing filter,
75% of the filter media was in great shape from my main tank.
But in the bottom of the filter was an old mechanical filter to screen the water before it reaches the bio-media,(this was also washed thoroughly with tap water)
But when i stripped the tank down i noticed this sponge had a mild stagnant smell to it!
Any idea what this means?

 

[drobbyb]

Possibly that could be rotting organics in the sponges. It's hard to say exactly what happened. Usually with an under-performing filter you will see raising levels of ammonia and nitrite as well as nitrates still going up.

For the future, run a small HOB or sponge filter in the main tank. When you move the fry into the next container, pull the filter and you will have an instantly cycled container ready for fish.