First Tankmate Down :'(

[iankent]

Got home from work early today to the nasty surprise that I'm a fish down already. I've tested the water again and again, and all the results are ok (Ammonia 0, Nitrite 0.25*, Nitrate 5) - the 0.25ppm nitrite appears to be a mis-reading by the API test kit after using Seachem Prime (and has neared 0ppm after 24 hours).

We did what ended up being a 150% water change (we were confused by the Nitrite reading, until we found the info on false readings with Prime/API kit), and all the other fish seem to be happy enough swimming around enjoying themselves, so the only thing I can think of is stress? I'm sure theres a million and one reasons, but it seems odd that one suddenly dies while the rest have settled in fine.

It was a Cory that died. The rest seem fine, although the frogs have been hiding all day so its hard to tell!

I cant decide whether to blame this on myself for jumping ahead of the fishless cycling or whether its just "one of those things" so to speak - if there was anything glaringly wrong with the water tests etc. I'd have a reason, but at the moment its just unknown!

The fish were acclimatised and the water has been dechlorinated and the temp is 26deg.

Desperately need any ideas why this might have happened - is there anything else I should check the tank for, and assuming my water results are all ok, what other possible causes are there?

Thanks,
Ian

 

[ox5477]

Well the nitrite could be a culprit if there was any at all in the water. Some species are more sensitive to it's poisoning effect. I don't think I've heard of people having cories die in their aquarium so I'm not sure.

What are it's tankmates?

What size tank?

Did you have the cory in a shoal or by itself?

What species of cory is it?

 

[iankent]

Well according to seachem the nitrite has been detoxified (although there shouldnt be much/any in there due to water change), so that shouldnt be the cause - although trusting the invisible effect of seachem prime is a bit worrying

the cory was with 5 others - the other 5 still seem happy enough swimming around. theres 12 neon tetras, 3 dwarf frogs and a young siamese fighter in a 110L tank. IIRC its a julli - the woman at the shop seemed a bit confused to say the least, and the labelling wasnt great!

thanks!