help - fish deaths

[Hebdizzle]

I have had 3 random deaths in my 30 gallon tank in the past 2 weeks. Before I go on, here are my specs :

30 gallon, has been set up for approximately 8 months
fluval 204 filter (up to 40 gallons)
PH : 7.2
ammonia : 0
nitrite : 0
nitrate : <1
20 % water changes done weekly

These are the inhabitants (current number)
1) 13 white cloud mountain minnows
2) 1 flame dwarf gourami
3) 2 black tetras

In the past 2 weeks I have had pass away mysteriously and quickly.
1) A flame dwarf gourami (sometimes called fire gourami?)
2) A rubbernose pleco (AKA bulldog I believe)
3) A black tetra

All three have been found at the bottom of the tank wih no visual scars or indications of fighting or bad water quality.

Does anyone have any idea what could have made this happen? I haven't changed any techniques or added new fish or plants in over 5 months.

Thanks for the help,

Aaron

[mickey]

What do your fish feed on? have you changed thier diet recently?
Cheers.

[Hebdizzle]

I knew I forgot something:

Tetra Colorbits
freeze dried blood worms
freeze dried brine shrimp
live brine shrimp
the occasional guppy fry
Tetra tropical flakes
cucumbers and zucchini (mostly for the pleco, but the gourami likes them)
spirulina tablets also for the pleco

the only change was the freeze dried brine shrimp being added to the variety approx 1 month ago... Hikari brand.

Aaron

[yashinfan]

I use the Hikari brand brine shrimp, I asked my LFS about fish food, and he said that food wouldn't kill your fish unless it was spoiled. And since Hikari is really fresh-obsessed, I don't think that would have done it.

[Hebdizzle]

to tell the truth I have only fed the brine shrimp once :confused:

well thanks for the help guys... I really don't think I will get to the bottom of this. I have taken such good care of my fish, perhaps it is something beyond my control....


Aaron

[anonapersona]

When were the deaths in relation to water changes? Maybe the water company added something randomly for some problem you'd never hear about (line rupture, cleaning storage units...)

How close is this tank to overstocked? As the fish have grown, maybe they suddenly reached some sort of limit, and stress allowed some nomally benign bacteria to run rampant.

How old is the food? One of those many jars may have expired and begun to poison the fish, I've killed fish with 5 year old food.

Temp changes? Is the heater running? Check it for cracks, moisture.

Has the gravel been cleaned? Nasty gasses can accumulate and bubble out when the tank is bumped.

Wild guesses...

[valerie]

Have you added any new fish lately? What is the temp?Size of the tank?

Don't know about the rest but rubbernose plecos need cooler water and come from fast flowing water so they need high current well oxygenated water. Also they are wild caught and can come with internal parasites which wll eventually make them sick if un treated.

Sorry can't help with the rest.