# Do Cories not like EI or CO2?



## Martin cape (31 Jan 2013)

Hi guys. 

I HAD 8 Julii Cories. Now I have 3. They keep dying on me. Water parameters below:

Ammonia 0
Nitrite 0
Nitrate 28
pH (at the min) 6.6
KH 5
GH 5

I have sand substrate and my drop checker is this colour with still another half hour of co2 going in:






All my other fish are fine, swimming as normal, Cherry Barbs, Ottos, Lampeyes and rainbow fish. 

What is wrong with them? Do they not like the ferts or co2?


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## tim (31 Jan 2013)

I keep corries in ei co2 injected tanks mate not had a problem with them a few are about 3 years old, how deep is your substrate I've found sand can compact and become anaerobic , corries disturb the substrate a lot so can release trapped gas causing water quality issues ???


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## Viv (31 Jan 2013)

I had 6 cories in my planted tank that were fine with EI and liquid carbon. During the changeover to CO2 I lost two - and a fair few rcs too. I put it down to some problems I had with the regulator that made the CO2 levels sky rocket. I moved the others to my big tank rather than risk any more while I sorted things out and they've been fine. Of course I might be wrong about it being the CO2 (couldn't identify anything else though), or it may just have been the very high levels it went up to. It put me off keeping cories in a tank with CO2 though   Sorry, probably not much help!

Viv


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## Martin cape (31 Jan 2013)

To be fair I used to lose them in my last tank setup too. That had no co2 or ferts. Dunno why they die on me. 

Some of the sand is quite deep but I have Malaysian Trumpet Snails, a lot of them and they keep the sand aerated and freshly moved.


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## gramski (31 Jan 2013)

I've got a whole bunch of various Cory's and am running CO2 and they are all fine.


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## linkinruss (31 Jan 2013)

I've lost one with a co2 injected serious but I think it was ill when I bought. Down to three and they seem fine.


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## Nat N (31 Jan 2013)

Hi,
Corys have a reputation of hardy and easy adaptable fish. They do come originally from a relatively soft water environment... Also, being relatively “soft water”  fish, they should have much higher levels of tolerance to metals in the water (so EI should be fine). So, I don’t think either CO2 or EI bother them. My suspicion is on some not so friendly for them bacteria living in the substrate... They do like to dig and “hoover”... OR maybe compacted substrate which has become anaerobic? H2S can be very harmful for them.  I would suggest you first check on the presence of anaerobic “pockets” and S2H accumulating in the substrate. If this is the case, this needs to be sorted. If this is not the case, than bacteria is most likely the cause.


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## Martin cape (31 Jan 2013)

How to I check for hydrogen sulphide gas?


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## gramski (1 Feb 2013)

Nat N said:


> Hi,
> Corys have a reputation of hardy and easy adaptable fish. They do come originally from a relatively soft water environment... Also, being relatively “soft water” fish, they should have much higher levels of tolerance to metals in the water (so EI should be fine). So, I don’t think either CO2 or EI bother them. My suspicion is on some not so friendly for them bacteria living in the substrate... They do like to dig and “hoover”... OR maybe compacted substrate which has become anaerobic? H2S can be very harmful for them. I would suggest you first check on the presence of anaerobic “pockets” and S2H accumulating in the substrate. If this is the case, this needs to be sorted. If this is not the case, than bacteria is most likely the cause.





Martin cape said:


> How to I check for hydrogen sulphide gas?


 
I agree. Cory's are able to get oxygen directly from the air, you'll often see them swimming up to the surface for a gulp. Hydrogen sulphide is very toxic so if a cory were to disturb a pocket of hydrogen sulphide it may be enough to kill it. There's also the posibility that if there are anaerobic conditions in your sand that pathogenic bacteria are lurking in it. FWIW I would give the sand a good stir up regulary if you can.


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## gramski (1 Feb 2013)

Sorry, meant to add that hydrogen sulphide smells like rotten eggs.


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## foxfish (1 Feb 2013)

Martin, am I right in thinking your tank is only recently set up & you have three amazon swords it it...if that is the case then hydrogen sulphide is unlikely!
Also bear in mind your test kits are unlikely to be accurate!
Keep up regular water changes, 20 % a day or more will only benefit the tank.


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## Martin cape (1 Feb 2013)

I do regular 50% plus changes every Saturday pal. 

I'm maybe just unlucky with them. Always seems to be the smallest that go. The big lads seem to last. I'm putting plenty food in as I've seen loads of baby MTS.


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## Martin cape (1 Feb 2013)

Your correct about my tank though pal


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## MARKCOUSINS (1 Feb 2013)

Agree with foxfish i think you can rude hydrogen sulphide in your setup at the moment as is too new,Amazon Swords roots moving big time through the substrate and you say you have plenty of MTS.Cheers mark


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## AverageWhiteBloke (1 Feb 2013)

What's MTS? Being from your neck of the woods I know for sure your water is as soft as comes out of a RO kits. Being a fairly new set up it's highly unlikely that the sand is anaerobic as well but like mentioned it doesn't do any harm to give it a little rake about now and again. This is best done on water change day before emptying the water so that any nasties that get released get emptied out the tank. That's the problem with sand, I used to be able to see pockets of gas along the front glass which I just disturbed with a credit card on WC day. Gets a bit more difficult when the substrate is covered in plants though. Hopefully when the plants get really going they will pump 02 into the substrate through the root system.

When did they die mate, were they new additions? The EI salts won't be an issue and neither will the co2 content. What will be an issue is the difference between the water they did live in and the water they get put in. Most fish from the LFS have never been subjected to high co2 levels in their entire lives and often we buy the fish from the LFS get them home about the same time that the co2 is at it's peak. There are things you can do to relieve a bit of this stress on the fish and give them more time to adapt.

Personally I try and purchase fish the day I do my water change and preferably in the morning. The reasoning behind this is when dosing EI the levels are at there lowest value on this day and the disturbance of the water will gas off a lot of the co2. Put the new fish in a bucket and as you remove your water add a small amount at a time to the bucket with the fish in until the majority of the water in this bucket is tank water. Then go and have a brew and post some pictures of your tank on ukaps  give them as long as you can is the general rule of thumb the longer the better. Net the fish out the bucket and put in the tank. This also benefits in a way because generally the lights will be off and the residents in the tank will be too busy avoiding you to pester the new inmates putting them all on a level par, especially with cichlids in there which feel they have to defend their territory at all costs. Then slowly put the new water in. When I say the EI levels are at the lowest don't confuse that with them doing any harm, it's just that you don't want the fish going from one extreme to the other. In the LFS they usually would be kept kno3 free with very little co2. Even a couple of hours is relatively a very short time for a small fish's system to adapt to such a big change in conditions.

Also bear in mind that some fish just die unfortunately. Even when carrying out all these procedures it can still happen and people often knee jerk and want to buy a test kit and blame nutrients and co2 etc. If you're sure everything is ok in the tank maturity wise then you doing some extra messing without good reason will just compound the problem further. I always fancied some ottos in my tank but never had any luck with them. Well mature balanced tank with healthy fish in I carried out all the measures above probably over a five hour period with six ottos from p@h. The next day 3 were hanging at the bottom not looking well which I found two dead the next day and over the course of the week one by one the others died. I have no idea why it happened but it certainly wasn't the tank.

Sometimes it is what it is! Next time I'm going to get a few to put in my shrimp and let them grow a bit and possibly even try and breed them. I usually have more luck with the fish I have bred myself. Fish are often under nourished in the LFS and going to your house is the third leg of the journey sometimes in the space of a couple of week. The move in to your tank can often be the final nail in the coffin so it's best practice to make this as stress free as possible.


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## MARKCOUSINS (1 Feb 2013)

Malaysian Trumpet Snail mate.Cheers mark


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## AverageWhiteBloke (1 Feb 2013)

Ok I should have guessed.


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## Martin cape (1 Feb 2013)

I've had them in about 8 weeks so they should be settled. I think I am just unlucky. The 3 left look healthy enough. 

Funnily enough my 6 ottos are doing great lol. Never had or have bother with them 

Water change day tomorra. Need to get my finger out now. Co2 comes on at midday lol


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## Nat N (1 Feb 2013)

Hi all,
I am still convinced that the reason of the Cory’s misfortune lies in the substrate. The fact that the Ottos are doing fine just proves this. I am sorry, I did not know your tank was new –so, this eliminates the H2S poisoning. HOWEVER – this must be the substrate (Ottos do not dig like Cory’s do). H2S eliminated out of equation, one more thought/possibility – do you have anything under the sand? Sorry – I did not follow your tank story and may be asking you to repeat what you already posted... Do you have any ferts under the sand (e.g. root tabs?) If you do, then they could be a problem if not buried well. Cory’s  could have consumed small particles of the tabs whilst digging about, which became fatal to the weakest of the fish... I do not think water parameters would affect them – being probably tank bread in the UK - but “eating” something “nasty” could (like dogs consuming chocolate)...


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## ghostsword (2 Feb 2013)

Cory's do well in EI and high CO2, at one point I was breeding them on such a tank.. a right plage it was.. worse than guppies.. 

Your fish are dying, then you need to look either as a sick batch, or just old age. Very seldom Cory's die...


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## Martin cape (2 Feb 2013)

Yea I have sera Florena tabs under there that seem to have broken up and loads of white bits on sand. Don't use them anymore but they are still there somewhere.


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## Nat N (2 Feb 2013)

Well, this is what is killing your Cory's, unfortunately...


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## Martin cape (2 Feb 2013)

Damn. There's nothing I can do then really. The tabs have disintegrated into a million bits now.


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## ghostsword (2 Feb 2013)

Why would Florena tabs kill the fish? That is a bold statement..  


___________________________
Luis 
@ghostsword


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## AverageWhiteBloke (2 Feb 2013)

I sometimes wonder if there is already a bacterial infection going that they succumb to or something they have never been exposed to. Nothing worse than just watching them drop by one and you can't pin point anything wrong.


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## Martin cape (2 Feb 2013)

I know. I got sand especially for them. Last setup had gravel and wore the bar bells down. The ones I have now don't seem to move much either.


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## Nat N (2 Feb 2013)

ghostsword said:


> Why would Florena tabs kill the fish? That is a bold statement..


Because I’ve been there myself a few years ago – overzealous on my new experience with planted tanks. The first batch of corys died. I did think, indeed, that it was a “bad batch”... Then another... Then another type of corys... then another one... Famous Diana Walstad was kind enough to reply to my email and we eliminated one thing after another: H2O, bacteria and finally – poisoning on ingesting particles of Laterite which I had at the time cupped with very small grade gravel (nearly sand grade). Did you see your fish in the feeding frenzy when they accidentally pick up their tank mate’s poo and spit it out? Well, tiny particles of this poo are swallowed – no harm there. HOWEVER there is harm when a fish swallows a tiny particle of a root fertilizer.
I have corys now with Eco Complete – they live for ages. I have had them since I don’t remember when. So, this is the only thing I can suggest - cory's are not known to be inbred, so a "bad batch" is a rarity.


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## Martin cape (2 Feb 2013)

Bet that's what's doing it. I used some in my old setup too. Snails must be bringing bits up.


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## AverageWhiteBloke (3 Feb 2013)

Excellent a bit of a breakthrough. I use osmocote for enriching the gravel pushed in as deep as I can get it. They have less of a tendency to break up.


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## Nat N (3 Feb 2013)

Yep, I agree about osmocote. I am not suggesting that it is completely impossible to keep corys with laterite but it needs to be really-really well covered. Interestingly, I just tried to remember if I saw any really artistically scaped tanks with corys or other fish which digs – and could not remember one...
I think this also works as an argument in favour of EI dosing – no fish will get poisoned.


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## abloomer (18 Feb 2013)

I have bred Sterbai's in a community tank with Co2 and dosing EI.

How they survived is beyond me, as I also have a syno in there too!

The joys of a planted tank I guess....lots of hiding places!


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