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I seem to be unable to keep corys alive in my 150 gal tank and am having a hard time figuring out why. I have tried three different batches with almost a year in between each attempt and have had the same results. The most recent batch was labeled as "Green and Gold" at the store, but they didn't have the scientific name. They look like green corys, but with gold fins. Previous batches were melanistus and julis. Other fish that have been added at the same time as the corys are doing fine and have no issues.

Here are the tank params:

Temp 78
Gh 7
Kh 5
Ph 6.9 - kept there by adding CO2
Ammonia 0
Nitrite 0
Nitrate ~10ppm
Phosphate ~1ppm

This is a planted tank with swords, crypts, java fern, ambulia, and other plants. I add CO2 and ferts for the plants. The substrate is 75% Onyx sand and 25% fine grained gravel.

I added the latest batch of corys on Saturday and have already lost all but one. I only got 5 due to past failures adding them. I added two juvenille angelfish and one small clown pleco at the same time (from the same store) and they are doing fine. The corys at first just continuously swam up and down the glass. They eventually stopped doing that, but never acted normal. They would sit high up in the plants instead of on the tank bottom. I actually pulled the three that were still alive out of my 150 gal tank yesterday and put them in a 45 gal tank that only has some danios in it. Two of those three have already died, though.

I have been putting melafix in both tanks as a preventative measure against any bacteria the new fish may have been carrying and stress from new fish. It didn't seem to help the corys.

At this point I'm pretty much at a loss to explain why they are dying. The tank has 20-30 tetras, 3 angelfish, 2 rainbows, 2 gouramis, 6 otos, 4 SAEs, and 2 clown plecos that are all doing fine. Only the corys seem to have an issue. Many of the fish in the tank are fairly large and I wonder if the corys are just scared, but that doesn't seem to make much sense. The corys didn't seem to do any better when I moved them to my 45 gal tank so that would seem to indicate it's something in the water. I have heard that corys are sensitive to metals in the water. I have a 25 year old house with copper pipes and, believe it or not, what I think is the original water heater. I'm wondering if the water heater and/or pipes could be leaching metals into the water that the other fish don't mind, but affect the corys. I'm just grasping at straws and any theories are welcome.

David

I'll start from the back and say that I don't think cory's are particularly more sensitive to copper or other metals leaching into the water than any of the other fish you list, they are generally fairly hardy.

For example, Oto's should suffer the same...

I have Corys with 5-6" long Satanoperca jurupari, so unless your fish is SIGNIFICANTLY larger than that, I'd say your "large fish" isn't a problem as such.

What do the corys look like when they die?

Would it be possible to sort out the water condition problem by setting up a smallish tank (say 10 US gallon) with some "pure water", either RO water or perhaps you can buy some spring-water or some such [even here in England, you can buy bottled spring-water for about $0.3 per two liter, so a small tank should be doable for not too much money - don't buy the bubbly stuff tho'! )

Finally, could you update the "profile" on the top-right of the page to contain your location (if you live in the US or Canada, a state/province and country, otherwise country is enough, but you can give more details if you want) not only is it part of the planet catfish rules, but it's also helpfull when giving advice to you that works for where you live.

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mats

Could you name the Corydoras species involved?

I'm in the metro Atlanta area. Gwinnett county. I thought of seeing if I could find the local water report, but haven't yet. The fish store I purchased the corys from is in the same county so theoretically would have the same water source. I would have put the location in my profile, but it let me create one without it so I didn't notice it was required.

I'm not sure of the species. They were labeled as "Green and Gold" and appear similar to the aeneus (at least to me), but with gold fins.

They appear mostly normal when they die. No fin or body damage. The gills have a reddish hue, but not dark. That's the only indication to me that it's some sort of respitory/stress related issue.

I do have a 10 gallon tank that I keep running as an emergency tank. I could drain it and put in some DI water. I have a small DI system that'll take a while to make 10 gallons, but it's doable. I've kind of neglected that tank so I'll have to clean the alagae out fist. I'll do that tonight if the remaining cory is still alive. I don't think it will be, though. I'm really just attempting to figure out why this is happening (only to the corys) as it's really frustrating not understanding what is the issue.

Thanks for the help.

David

Yes, I know that it doesn't actually ask for a location in the profile - I don't know if it's easy to make the code in the phpBB to actually check - probably not that difficult, I'd say - but I don't have the source-code here, so I can't look at it. I may do later on. It works reasonably well to ask nicely too

Back to the fish: You should be able to get a water report for your local area from the water board, but I doubt that it will say that your water has lots of nasty stuff in it - not that it would be incorrect, but I'd rather think that most common Cory's will survive most things that are allowed in tap-water and then some.

Make sure that you don't run PURE DI water, as it's probably too low on minerals to work well. Also, if you go into a local supermarket and get some drinking water at a couple of dollars for a big bottle (5g or so), that should be fine for this purpose - we're just trying to eliminate the local water supply from the possible causes... If the cory(s) survive in this water, then we'd have to look closer at what could be in your tap-water. Copper wouldn't be a cause, I'd guess, because:
1. tap-water is pretty inert to copper unless you have VERY acidic water - which you don't!

2. Copper is often used in medications against parasites, and whilst this is indeed poisonous to catfish and other scale-less fish, it's at a level where the water is clearly tinted blue-green, and I think you'd notice if this was the case with your tap-water...

I understand your frustration, and I hope that we can find a solution to the problem.

You didn't specify what temperature your tank is... Some corys aren't particularly happy with HIGH temperatures (up to about 26'C - 78'F or so is fine for almost all species), but I doubt they would die quickly from this, they would most likely just have a shortened lifespan. If they are commercially bred, they would also most likely be bred in SE Asia, and they don't chill their breeding tanks (unless it's ABSOLUTELY necessary), so the tanks are often kept at more than 26'C there, and if you have some form of C. aeneus, then it's almost certainly a commercially bred form.


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Mats

What species of Cory are they?

The only thing that really comes to mind is that the difference between the water in the store and your water is vastly different. Did you check the parameters of the water they were in compared to your own before you released the Corys. To be sure that the fish are acclimatised properly they should be introduced to the new water very slowly, this I do by putting the new fish into a fairly large container with the water they arrived in and then add your own water via airline tubing until the container is full. Then net the fish out and put them in their new home. Introducing new fish into water with parameters different to what they are used to can shock their systems and cause all sorts of problems.

Ian

Temp is 78F. I went back and added that to the original post probably after you read it.

I have stuff to "reconstitute" the DI water, but buying something from the store is probably easier. I was thinking the spring water at the stores wouldn't be ok for fish, but it sounds like that's not the case.

David

Aqua Dave wrote:Temp is 78F. I went back and added that to the original post probably after you read it.

I have stuff to "reconstitute" the DI water, but buying something from the store is probably easier. I was thinking the spring water at the stores wouldn't be ok for fish, but it sounds like that's not the case.

David

78'F is fine for most corys, so it should be fine.

I agree with what Ian says about acclimatising the fish. If your water is noticably different in pH, temperature, conductivity (roughly the same as hardness) etc, it can shock the fish, indeed.

I think any "drinking water" is fine for fish-keeping, but obviously you would have to check the same things as with your tap-water when it comes to making sure the chemistry is similar - and if they have different types of "drinking water", try to find the one with the lowest mineral content. But for example "Tesco's" (English supermarket chain) has still spring water that is less minerals than my fairly hard tap-water... And what else would be different from tap-water (except it's got less chlorine )

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Mats

Coryman wrote:What species of Cory are they?

The only thing that really comes to mind is that the difference between the water in the store and your water is vastly different. Did you check the parameters of the water they were in compared to your own before you released the Corys. To be sure that the fish are acclimatised properly they should be introduced to the new water very slowly, this I do by putting the new fish into a fairly large container with the water they arrived in and then add your own water via airline tubing until the container is full. Then net the fish out and put them in their new home. Introducing new fish into water with parameters different to what they are used to can shock their systems and cause all sorts of problems.

Ian

I do pretty much the same thing, but leave the fish in the bag they came in. I gradually add water from my tank to the bag till it has about double the water when I started. The bag is sitting in the tank so that the temp in the bag equalizes to the tank temp. I pour the water from the bag through a big net into a pan so that the fish wind up in the net and then in the tank they go. This is the method I used for the corys and all the other fish I put in the tank.

David

Have you checked back at the store to see how the rest of the corys from the same batch are doing?

I would suggest to check if a lack of oxygen at the bottom of the tank might be the problem - especially reading about the swimming and resting behaviour. How is the respiration rate of the Corys? Do you switch off the CO2 supply at night?
See:
http://www.planetcatfish.com/shanesworl ... cle_id=313

I would suggest to check if a lack of oxygen at the bottom of the tank might be the problem

I would think that as cories can breathe atmospheric air, they would be the last to suffer from oxygen problems.

I would think the plec would be first to show distress if this was the case.

I'm thinking perhaps the stock is diseased in some way, or that for some reason the tank water is vastly different from the shop water, and the fish can't acclimate.

racoll wrote:I would think the plec would be first to show distress if this was the case.

I'm pretty sure that Panaque spp. can breath atmospheric oxygen too - as far as I know it's only Chaetostoma that aren't able to do that in the Loricariidae family.

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Mats

I'm pretty sure that Panaque spp. can breath atmospheric oxygen too - as far as I know it's only Chaetostoma that aren't able to do that in the Loricariidae family.

Didn't know that.

I thought it was only species such as Otocinclus, Glyptopterichthys and Hypostomus that could do that.

everything sounds fine...i'd lean towards the trace metal issue..maybe buy an ro unit..

My CO2 is hooked up to a Ph controller so it only comes on when the Ph rises above 6.9. I run a sump on my 150, which I think would keep the water fairly well oxygenated.

This is the third batch of corys I've tried with the same results. So I don't think the stock at the store was bad. I looked at my records and I added the first batch Aug 2004, the second batch Aug 2005, and then this last batch. The tank has been running since early 2004. The symptoms seem to be the same each time.

I went home yesterday to find two live corys, which was a surprise. One was on its side breathing extremely rapidly when I left for work and I figured it was a goner. They still weren't acting normal, but they looked better. I went to Publix and got some of the Publix brand drinking water. I cleaned out my 10 gal tank and filled it up with the bottled water (As an aside, it appeared that my 10 gal tank had reached a state of bio-equilibrium where there was enough plant detritus to keep the plants growing without adding any fertilizer. Kind of cool, but I've disturbed it now.). The corys are now in that tank and we'll see what happens. They didn't appear much better this morning, but they didn't seem worse either.

I moved into this house about 3 1/2 years ago and I didn't seem to have issues with corys in my old house. I didn't have the 150 gal tank at the old house either. I'm only about 10 mins away from my old house so the water supply should be the same or at least similar. That's one of the reasons I suspect something to do with the plumbing at this house (or possibly even the supply lines to the house). My other thought with the trace metals was that they might be more concentrated at the bottom of the tank since they would tend to sink. Water circulation in the tank isn't great (which I'm hoping to rectify over Thanksgiving) and that may contribute to the problem. Anybody know if there's a way to test for metals in the water? I guess I could have a pro come out and do a full water test.

Something else that could be an issue, though this is really reaching, are snails. The tank has lots of common pond snails that came in on some of the plants and have multiplied. I kind of like them and haven't attempted to eradicate them. I do find lots of snail shells from dead snails and I've heard that dead snails can poison the water if enough die. Seems like it would take a lot of dead snails to pollute 150 gallons of water, but when you've looked at the normal stuff it's time to look at the weird. Also seems like the other fish would be affected as well.

I'll see how the corys do in the bottled water. That may give an indication as to where the issue lies.

Thanks for the reponses and if you have any ideas to try let me know cause I'm pretty much out.

David

I do find lots of snail shells from dead snails and I've heard that dead snails can poison the water if enough die.

Any dead snails will show up in your ammonia, nitrite and nitrate tests as elevated levels, so I doubt it is this.

I'm a bit stumped on this one.

Best of luck with the 10g.

Aqua Dave, I live in Atlanta and I can tell you that if your water is as bad as mine, I wouldn't be too surprised. I solved my problems with a DI unit, and I mix this DI water with tap water. My older cories are more than 5 years old now, and they keep spawning.
Good luck!

RiC wrote:Aqua Dave, I live in Atlanta and I can tell you that if your water is as bad as mine, I wouldn't be too surprised. I solved my problems with a DI unit, and I mix this DI water with tap water. My older cories are more than 5 years old now, and they keep spawning.
Good luck!

What ratio of DI/tap water are you using? Is it a 50/50 mix? What DI unit do you use? I have a small one, but it would take a long time to make the amount of water needed to do a water change in my 150. I'm doing 50 gallons at a time. Thanks.

David

Aqua Dave wrote:[What ratio of DI/tap water are you using? Is it a 50/50 mix? What DI unit do you use?

It depends on the tanks; for some I have 50% DI/ 50% tap, for others I have 100% DI (trace elements and electrolytes added afterwards). I use the Kent Marine 200 DI (3 stage filtration). All RO/DI units will require time though, since the water has to go through the resins very slowly. Kent say the resins for my DI unit can last for 6 months depending on the source (i.e. original quality); my water is so bad that at times I have to change them once a month...

in the long run an ro unit would be cheaper than changing those resins..and easier.

I would still like to know what species of Cory we are dealing with here. All Corys do not require the same conditions, in fact there can be a vast difference.

Ian

Why don't you quarantin your Corydoas so yo can easily treat them, if necessary?
Also many Corydoras are run down when you buy them and in a quarantine tank you can be sure to get the food to them without competion and after a few weeks to a month they will be in much better condition when you add them to your display tank.

When I read what size your tanks was, 150 gallons, the first thing that popped in to my mind was; the water is to deep for them.

How deep is the tank, and what would you guess the corys size was when you put them in there?

The younger they are, the more sensitive they are to changes in the water pressure. Small and young corys easily go in to chock and can die if the water depth increases too much and too fast.

Ian,
With regard to our question, this is what Dave wrote early on in the thread:

Aqua Dave wrote:I'm not sure of the species. They were labeled as "Green and Gold" and appear similar to the aeneus (at least to me), but with gold fins.

I think that theory applies better to Corydoras fry than it does to half or full grown Corys in good health.

It's been about a week so I thought I'd post an update. The two remaining corys are alive and seem to be doing better, though not completely healthy. They were looking lonely and weren't very active so I got them some buddies to try and perk them up. I now have 8 emerald green corys (from Pet Smart of all places) in the 10 gal tank along with the 2 green & gold. They all seem to be eating and doing normal cory things. The 2 green & gold don't necessarily hang out with the others, but I think just having them in the tank has helped.

This would seem to suggest that it was something in the 150 gal tank that was causing the corys stress. It's hard to say at this point if it was the water or something else. The 150 is very deep, 28 inches, though I hadn't heard of depth being an issue for corys. I found some places on the web that will test water (for a steep $150) and am planning on getting my tap water tested to see if it contains anything it shouldn't. I'll figure out what to do with the water from there.

My plan at this point is to leave the corys in the 10 gal tank and let them grow some. They aren't tiny, but they aren't large either. I'll keep using the bottled water in this tank until I have the results of the water test. When they get to be a good size and I'm happy with the water in the 150 then I'll try putting them in it and see what happens.

Thanks for the responses.

David

Hi Dave,
Your water department will mail you a free comprehensive analysis of your tapwater. All other problems in the aquarium water are related to things under your control. I suspect that you just bought some run down catfish that would have died no matter what you did. The depth of your tank is completely irrelevant. Save your $150 for fish and plants or a better filter. Whatever, but not on testing. Aquarium water test kit for $20 or so will tell you all you need to know about the tank water.

I'm with Larry on this one - $150 to test the water is a waste of money. Your local water board (or whatever the term is for "local supplier of tap-water") should do this for free - I got one from Thames Water within a few days of asking via their web-site.

The money you don't spend on that, I'd suggest you spend on something like a RO or DI filter.

I very much like the that I think is what you have added to your small tank. Very suitable for a big tank, as they get a bit bigger than your average Cory species - but they grow quite slowly...

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Mats

I haven't seen Aqua Dave's fish, but if he got them at PetSmart, and if they were labeled "emerald green cories", then they are not corys but Brochis splendens.
PetSmart is a chain, and offers the same products in each store. They are labeled this way in the ones near me, too.
In fact, even the LFS labels two different species of Brochis "emerald cory" or "large green cory" or "emerald green cory." They do it this way to attract buyers who like corys, and will buy them, but have never heard of Brochis.
I got some very nice B. britskii (identified by Ian on corydorasworld) for about $2.69 each, which seemed cheap to me. Care is the same as for Corydoras, and they will "school" with Corydoras, and sleep with them, too. It's really sweet to see. Brochis are interesting to watch, too. They often swim upside down at the top, searching the roots of floating plants for food.

Aqua Dave, you ought to count the dorsal fin rays for a quick confirmation of which species you have.