Cory (Sterbai) Dying

[LadyRiv.]

hi,

i need some help please,

last week wedensday i bought 2 cory sterbai for my tank. the corys seemed very small, i introduced them to the tank, other fish i have is 6 platys, 6 danios, 1 guppy and 1 molly, 65ltr tank. the fish were fine when put in but did not move around a lot, mainy hiding in the cave and ornament. i feed flakes, sinking small pellets and tried frozen bloodworms. i could not seen them eat but they were "hoovering" the gravel. i bought another 2 corys from another store 2 days ago as i thought they might lack company, the new 2 corys are twice the size and very lively. all 4 of them hanging around together.

yesterday, one of the smaller corys died, no particular reason i could see, this morning, one of the big cories was lying dead in the tank, looked normal. when my husband came home today, the other bigger cory was swimming upside down and breathing very heavily. tried to get up but kept on falling to the ground (if that makes sense), then it was floating like dead again. he fished it out and it is in a bowl and seems to do better.

i checked the water, api master test kit - amnonia - 0, nitrite 0, nitrate between 5and10, currently kept at 26 degrees celcius.

what can be the cause? i have gravel in the tank, the mouth of the fish seem fine, i am worried that the gravel might be too sharp but i checked with the stores first and they said gravel is fine. are sterbais more sensitive than my other fish as no problems with the other fish at all.

what can i do? i don't want them to die and only want the best for the fish? is the water too warm for them? the one is the bowl seems to recover but no heater so the temp is dropping. but i am worried to put him back in, i cannot see any picking or bullying in the tank.

 

[Baccus]

Since you also have a molly in the tank and a guppy I was wondering if you added salt to their water, guppies don't really need salt and there are two views on if mollies actually do I have seen mollies kept in salt free water and ones kept with a bit of salt and both seemed fine and healthy and had been breeding generations in either conditions for years. Any way I digress... The reason I asked about the salt is that cory's can't handle salt. So that might be your culprit right there.

The gravel as long as it isn't sharp shouldn't be too much of a hassel although the sterbai (any corydoras really) will prefer sand.

The temp might be a bit on the warm side I generally keep all my fish around the 22degrees c mark and all are happy and healthy, in summer the temp does creep up higher thanks to me living in hot humid sunny old Queensland but I try not to let the temp get below 22 in winter. I would try dropping the temp back to 24 degrees gradually and make sure none of your other fish show signs of stress at the lower temp.


Good luck with your sterbai they are a beautiful cory.

 

[LadyRiv.]

i started dropping the temp yesterday, the last 2 corys seem fine but don't move much. i don't have salt in my tank, so salt cannot be the reason. i just wonder if there was something wrong with the fish when i got them as one died within 48 hrs and the other within a week. as i said, all the other fish are fine. i will see how the other 2 corys do over the next couple of days/weeks and might change part of the tank or the whole tank to gravel. and if the corys are fine, i will add new ones as they should be in a bigger group.

thanks for the reply baccus

 

[fluttermoth]

I don't know exactly what's wrong with your corys, but I'd advise some big water changes. There are all sorts of things htat could be in the water that we can't/don't test for.

Plenty of large scale water changes should always be your first emergency action. Hope the rest of your corys pull through ok...

 

[coldcazzie]

I think its unlikely to be the temp as sterbai cories are the cories that are recommended for discus setups because they can handle the high temperatures (28-32 degrees) that discus like, unlike most other cory types which require low temps: 20-24 degrees.

I realise that doesn't actually help in terms of what's actually wrong, but it does mean you can rule temp out.

Oh, and +1 on the large water changes

 

[LadyRiv.]

hi, unfortunately i had another cory die last night and am only left with 1 of the small ones. i do water changes every 6 days and have done a larger water change (approx 45%) after the first cory died. 1 died within 7 days of purchase and 2 died within 3 days of purchase, maybe there was something wrong with them before i bought them, no signs on the fish themselves which might hint towards the cause of death...