Pygmy Corys

[Majjie]

I have a little 40l (10.5 USg) tank which has been set up for 2 years. I stripped it down about five weeks ago and washed the gravel (but filter wasn't touched - except for a rinse). There were some cardinal and glowlight tetras in there at the time. Last week I did a 100% water change (but water was from a mature tank) and swopped the tetras for 6 adult female platys and a few baby platys. Water was harder and slightly more alkaline - but filter didn't seem to be affected at all - stats all ok.

On Saturday I added 6 little pygmy corys (C.pygmaea). They swam about for a bit (they're absolutely lovely) and then disappeared at the back of the tank. There's lots of places they can hide (see pic) I've only seen one or two at a time since then but they've seemed quite lively.

Today though I found a little body

Water stats: ammonia and nitrite 0, nitrate 25, pH 7.5
I've done a gravel vac and 25% water change
Platys are absolutely fine

Anything else I can do?
Only meds I have are Myxazin and Pimafix - should I add either?
Could a problem with the tank have affected them so quickly?
Are pygmy corys a bit sensitive like pandas? I don't know much about corys.

whoops! no pic. Here it is.

 

[The-Lion]

I had two pygmy cories die on separate occasions, water stats where ok, there was no disease & all in the tank except my cories where thriving. On both occasions there had been a significant rise in water temperature (from 78 0f to 84 0f), so this is what I put their deaths down to. Since I’ve learned how to regulate the water temp in the tank they have been fine. So I do feel they are fairly sensitive.

Mine spend a lot of time in & around the planted area of the tank, which I think I’m right in saying is their preferred habitat, so I wouldn't worry about them hiding as it seems normal behaviour. If like mine they will start exploring the tank as a group or in couples often tagging on to the shoaling tetra's.

 

[Majjie]

Thanks for that. Fingers are crossed for remaining five.

 

[aloaring]

Glad i did a search for this , i recently bought 8 pygmy cories and within 2 weeks 2 have died for no apparent reason water tested fine and no sign of disease. But with the recent heatwave we've had,you've now got me wondering if a rise in temperature affected them .

 

[WILDER]

Corys are very prone to bacterial infections, did the cory look bloated and lay to one side in the tank.

 

[Majjie]

Don't know about aloaring but I didn't notice any bloating on my dead pygmys. Three of the original six died and I hardly ever saw the three survivors - so on the basis that they like company I bought four more. They've been fine for the last few weeks and now swim about more.

Also I have been meticulous with the gravel vaccing since. Reckon the gravel might initially not have been at its cleanest (because I'd stripped the tank down a few weeks before, I sort of thought of it as clean )

Unfortunately another pygmy died at the weekend - when the tank got up to about 86 degrees. I reckon that could have been the temperature.

Remaining six are lively still.

So, from my limited experience aloaring, I'd say it could have been the temperature - but also I'd keep the sand/gravel VERY clean

 

[WILDER]

My three panda corys first bougt are still going strong one half years, I added another three two weeks later and they all die, but they had red patches on the tummy area, always increase aeration in hot weather, as it's tough at the bottom of the tank for bottom dwellers.