Tropical Fish Forum
Tropical Fish Keeping Help and Advice => Fish Species => Catfish => Topic started by: Vanadia on December 11, 2020, 08:44:29 AM
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I started keeping bronze corys in my 105 litre aquarium back in September. Every went well for 4 weeks, then one of the corys become increasingly lethargic and died. I got 3 more (as I thought they might be happier in a group of 6), one died within a few days (despite careful acclimatisation) and the LFS replaced it, so I had 6. Then 2 more died within a couple of weeks (same symptoms). At that point I treated the tank with medicine for flukes/parasites. Everything seemed to have calmed down for a few weeks, and then this week I lost another, same lethargy/not eating then dying a few days later.
I am down to 3 now, and unsure if I should get more (perhaps from a different store) or if there is something in my tank that they don't like.
My tank is at 25-26 degrees, small (but not fine) gravel, soft water, plenty of hiding places, lots of plants, 2 airstones, tank mates are rasboras and tetras. I test the water regularly and I have never seem ammonia or nitrite go above 0, and nitrate go above 10 - 20. Is there anything obviously wrong with my tank that might be causing cory deaths (I wonder if the gravel is OK), or is this just bad stock.
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Are you able to see whether the remaining 3 fish have full-length barbels? (Compare with pictures of bronze cories' barbels online.) If they don't, then it's likely the gravel is wearing them down and ultimately leading to their demise, in which case I wouldn't get any more cories unless you change the substrate to sand.
A few other possibilities:
* Did you quarantine the new cories for a month or so? I'm reading it that you possibly didn't, in which case their deaths could possibly be accounted for either by the substrate wearing down their barbels or them succumbing to something in the tank.
( Do you know if your water softness is very different from the LFS's water softness? (Might be worth checking out the LFS's postcode on the water supplier website and/or finding out if they harden the water in some of their tanks. It might well be that the recent ones succumbed either to a sudden change in water softness / PH - or possibly just couldn't cope with the stress of transit from wherever > LFS > your home.
I wouldn't get any more bronze cories for now. I also have very soft water but didn't have success with pygmy cories. If I were you, I'd wait for a few months (in the hope that anything in the tank might dissipate), then possibly consider a different type of cory if you're particularly keen on them and prepared to change the substrate to give them a better chance (or buying bronze cories at a different time of year when the stock might be better quality).
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I don't think that their barbels are full length based on pictures I have seen online, and some of them didn't seem to have very long barbels when I got them either. I think one of them has very short barbels. They were also being kept in a tank with gravel larger than mine at the LFS.
The LFS is only a 5-10 minute walk from my house, so I don't think that the water should be that different, and the travel time minimal. I also acclimatised them slowly by adding water gradually to the bag for at least 30 minute before adding them to the tank. I didn't quarantine.
I have no plans to change the gravel to sand, I don't mind using sand but gravel changes are alot of stress for the fish, and last time I changed substrate I lost a few fish, so I probably wouldn't get anymore if the gravel is the issue then.
However I do have an existing 80l tank with a sand substrate in it which is only 61% stocked according to AqAdvisor. It contains a bristle nose pleco and some black neons, so that could be an option for the 3 remaining corys if they are ultimately going to die if I leave them in a gravel tank. Can their barbels grow back?
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Just to add, one of them did have black barbels after it died (that was the one that died 2 days after purchase). Not sure if that is a sign of an infection or damage.
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can grow their barbells back, the sharpness of the substrate is as if not more important than the size - sharp sand can also cause issues. If the bristlenose is on I would assume the sand is ok, but I would be nervous of moving anything from your Cory tank to the 80l tank given your experiences.. interested to hear others thoughts
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Thanks for the replies.
I have attached a photo of the sand in the 80l aquarium, and also of the barbels on one of the corys.
I guess I am wondering if the barbels have been damaged by the gravel in my aquarium (I do wonder if some of them died of stress), and if so, would the 80l aquarium be more suitable for them?
My main concerns are potentially introducing contagious diseases into the 80litre, stressing out the corys by moving them, and whether they would get along with a bristlenose pleco.
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And the sand picutre.
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I have corys in every tank that has plecs and they seem to be ok together. My BNs tend to be quite solitary, and the corys are more outgoing, so they tend to use different parts of the tanks. All my tanks have sand substrate.
Saying that, if you are planning to move your corys I'd be tempted to quarantine them in another tank before risking them in with your BN.
I think you may have a tricky decision head of you when you consider leaving the corys on gravel or moving them to the other tank. Whatever discussion happen here on the forum regarding the pros & cons of each option, the final decision is yours and we will support and assist however we can. :)
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Thanks
Yes it is a tricky decision! I do think that they would be better on sand in the long run, but I also suspect that corys don't deal with stress well (and moving to a new tank is quite stressful). I also don't want to put my bristle nose pleco at any risk either (he is my favourite fish!)
I find it very difficult to set up small quarantine tanks (around 15 litres). The smaller filters always seem way too strong, even if they are designed for a tank that size, and I have trouble keeping them cycled. Last time I used a small filter which had been in a established tank for 2 months, yet I still had ammonia and nitrite spikes. I am concerned if I put them in a quarantine tank I could end up losing them to either stress or bad water parameters. If anyone has any tips or suggestions on quarantine tanks, I would be interested to hear those.
Could I leave them in the existing tank for a period of time (not adding new fish or changing anything), and move them across if there have been no further deaths and no fish is showing any signs of disease?
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I agree that your corys would be better on sand long term.
I still think you may have been unlucky with your corys. The ones I have are generally quite sturdy.
Let's see what the others think and perhaps we can come up with some options for you. :)
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A couple of points:
* whether or not the cories would be stressed is hard to tell:
--- some/most of my fish have been very stressed out by a move, others surprisingly not at all; IME, attempts at capture indicate likely ultimate stress in the QT - evading capture suggests they would be stressed, whereas willingly going into the net/jug usually means they'll be unperturbed.
--- sometimes worth experimenting, and then either abandoning capture attempts or moving them back into main tank if problems evident in QT;
* filters for QT - yes, difficult to gauge, and volume turnover doesn't necessarily equate to tolerability by the fish:
--- the tiny filter that came with my ~17L QT is/was far more powerful than Eheim PickUp 45's adaptable flow that I bought for the tank when the aforementioned filter suddenly ceased; I also bought a Dennerle corner nano-filter for 10-40L as I wondered if it might be better, and I use it with its spraybar, but the two are very similar, and even very weak fish seem to cope with them fine. [NB overall preference probably the Eheim one as the Dennerle one required an additional module/media basket to use mature media from main tank in it.]
--- when you put the QT's filter in the main tank as an extra filter, did you ensure mature media was put into it? If not, then it's possible that it didn't actually get colonised by beneficial bacteria, hence the ammonia/nitrite spikes in main tank.
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I've set up my quarantine tank twice in the last 12 months.
The first time I used media from my main tank, and just to make sure i added enough ammonia to get 3 ppm. Next day it was still 3 ppm. A week later it was still 3 ppm. I ended up doing a 7 week fishless cycle before i could get fish. The main tank has a lot of plants, mainly slow growers but the surface is covered with floating plants which were water sprite at the time. Presumable there are very few bacteria in the filter media because of the plants.
The second time, I didn't bother with mature media. Instead, I moved 2 large water sprite floating plants and bought 2 bunches of elodea when I went fish shopping. Daily tests showed no trace of ammonia or nitrite in a 25 litre tank with 12 kuhli loaches.
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@Littlefish The filter I did add to my quarantine tank did still have all the mature filter media in it. Thanks for the filter suggestions. I was using the Interpet PF Mini, which is supposed to be for 5 - 40 litres.
@Sue I hadn't thought of trying to use live plants in a quarantine tank before, but as mature filter media doesn't seem to work, it is something I will try next time. I have plenty of elodea and floating plants in my existing aquariums which might contain some bacteria.
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Rather than the plants containing bacteria it is more that their photosynthesis utilises the ammonia excreted by the fish. As such it is important to ensure the quarantine tank is lighted if you go down this route as the plant will need the light to convert the ammonia from the fish into energy for their growth.
I do think that many underestimate the power of plants for filtration. Whilst flow is still needed in a health tank, I do sometimes wonder if my plants might not actually grow better if I removed my filter media from my filter as they prefer ammonia over the nitrate added in plant fertilisers.
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I should have added that my QT does have a light over it (which lives in the cupboard when not in use). I also used an old, cheap filter just to move the water round, the only media was some filter wool to remove any bits floating in the water.
As Matt explained, plants use ammonia as their source of nitrogen and they don't turn it into nitrite or nitrate, they turn it into protein instead. Ammonia is the preferred source of nitrogen with most aquatic plants simply because if they take up nitrate they have to turn it into ammonia to make protein, so it takes less energy to take up ammonia.
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That's good to know that plants can remove ammonia, without converting it to nitrite. The nitrite stage of the cycle always seems to take the longest!
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The faster growing the plant, the faster it takes up ammonia. Slow growers like java fern and anubias don't take up much; and at the other end of the scale are floating plants which take up more than other plants because they are very near the lights and can get CO2 from the air. Stem plants like elodea are also good at taking up ammonia, which is why I got some for the QT when I got the fish - and elodea is cheap.
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I do sometimes wonder if my plants might not actually grow better if I removed my filter media from my filter as they prefer ammonia over the nitrate added in plant fertilisers.
Hi @Matt
I did an experiment recently to check this out. And I hope to repeat the experiment soon. In short, I found that the plants (your plants, in fact) did not appear to take up the ammonium. Instead, nitrifying bacteria seemed to beat them to it - even with no filter! If you're interested, you can read more on t'other forum. You'll know the one I mean.
John
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Unfortunately I lost another cory today, down to 2 now. It died suddenly, it was eating this morning and I found it stuck to the filter a few hours later. I also had a neon tetra (which I had had quite a few years) die yesterday as well. Unsure if it is a coincidence or if there is something going around my tank. Water parameters are all fine.
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I would guess the problem is the gravel. Gravel of any kind is never ok for Corys. It wears away the skin on the barbels causing sites for bacterial attack.
Also ime a substrate change is not very stressful for fish if done carefully while the fish are in the tank. Scoop it out with a margarine container, replace with a margarine container. Start at one end and work your way across. The fish are usually very interested in what’s going on....
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I do have a tank already with a sand substrate (80 litre with a bristlenose pleco and some black neons) which I could move them into. It does have a few rocks in there (I use them to create a barrier between the filter and sand), would this be a problem?
However I am worried just in case it is not the gravel and they are infected with something.
I am thinking of setting up a small tank and putting the last 2 corys in there (I think around it's 12 to 15 litres). I would fill it with water from the main tank and adding some floating plants. Hopefully these will remove ammonia as suggested in the other comments, but not sure how I could provide enough light for these, would a desk lamp over the tank work?
I would keep this tank bare at the bottom. I will try the small filter I have (healthy fish have been fine with it in the past, but it's too strong for weak sick fish), and if it's too strong, use an airstone instead or look at getting another filter.
If they are still alive in a month and appear healthy, I would move them to the sand substrate tank.
What are everyones thoughts on this?
Thanks
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I have just found some spare sand so I would put sand in the temporary tank for the corys!
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I think it's worth a try putting the last two into the smaller tank with some sand.
Move some filer media from the main tank and put it in to the small filter.
See how it goes with a desk lamp for plants. It is something I've done short term and the plants survived.
Good luck, I'm keeping my fingers crossed for you and the corys.
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I agree with Littlefish's (helpful-as-always) advice. I've also used a desk lamp with live plants, for the quarantine tank, and managed to keep them alive - Amazon sword, from recollection.
Best of luck.
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Thanks!
I moved them into the small tank about half an hour ago. I found a small LED spot light for a display cabinet which I am using for the plants. I put some filter media from an existing tank into the small filter, and the filter flow doesn't seem to be bothering the corys. They seem quite relaxed now in the small tank, so hopefully being caught and moved hasn't been too stressful for them.
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This all sounds good.
On the subject of internal filters that you mentioned before [replies #8 and #10], I was sorting through some 2017/2018 PFK mags recently, and found a review of 50 internal filters. Your Interpet Mini isn't included but the PF1-PF4 four filters are. If you were thinking of trying an alternative, the following might be possibilities:
* JBL Cristal i30 - for tanks 10-40L, no flow control (a downside) but adjustable flow direction [FC/AFD], litres per hour when loaded 152 or otherwise max 200.
* Aqua Internal Filter 50 - 0-50L, no FC or AFD, l/hr loaded 68 and max 100.
* Superfish Aquaflow 50 - 0-50L, no FC or AFD, l/hr loaded 69 and max 100.
* Dennerle Nano Eckfilter - 10-40L, FC and AFD, l/hr loaded 106 and max 150 [I have this for QT].
[For comparison:
* Fluval U1 - up to 55L, FC and AFD, l/hr loaded 175 and max 250.
* Interpet PF1 - 45-68L, FC and AFD, l/hr loaded 237 and max 380.
* Eheim PickUp 60 - up to 60L, no FC but AFD, l/hr loaded 208 and max 300. NB. There is a 45 model but not included in review.]
[Dictated and checked for accuracy.]
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Thanks for the filter recommendations. I have swapped to a sponge filter for now as I felt the filter I was using was too strong (the corys became alot more active after I removed it and started digging in the sand), but I have still kept the filter media in the tank. I will see how they get on with the sponge filter for now, and look into getting a new filter at some point.
Corys are still alive in the small tank, but having trouble maintaining good water quality. I did not feed them on the day I moved them, or yesterday, but ammonia and nitrite have now climbed up to 0.25. I am doing a daily water change and adding Prime. I also added more filter media from my Betta tank and some gravel from the original aquarium (I put it in a filter bag) to try and help, but it doesn't seem to have done anything yet.
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Both corys are still alive and well in the quarantine tank. They seem to be enjoying the sand and their barbels are looking long. The plants didn't do too well though (maybe the light wasn't strong enough) so I have had to remove them.
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Glad to hear that your corys are doing well in the other tank. :)
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Today I noticed a white thing on one of the cory's backs. At first I thought it might be Ich, but there is only 1 spot, it doesn't seem to be attached to a fin and after a quick internet search, I understand that corys are unlikely to get Ich. The corys has been swimming around and it is still attached, so I don't think it's just a bit of debris or a bubble.
There has been a small ammonia spike in the tank this week (up to 0.25ppm) which I have been dealing with using Prime and daily water changes of 50%. The fish have showed no signs of stress at all.
Does anyone have any idea what this could be?
I have attached a photo. Unfortunately it is not good quality as the corys swim away when I go anywhere near the tank. It is just the spot on the back, there might be bubbles in the water which look like other spots in the photo but they aren't.
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It looks much smaller now, wondering if it is an Ich that has burst or just debris which happened to be stuck to the fish for a while. I may leave it another week or 2 before putting them in the 80 litre aquarium to be on the safe side!
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If it's just an isolated dot like that, I wouldn't worry too much. I've had the occasional fish with their own little marking like that, either becoming permanent, coming and going, or temporary. I think your plan of postponing moving the fish sounds wise, as a couple of weeks ought to give some indication of whether it evolves into anything or simply remains static or disappears.
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Unfortunately I lost one of the corys and the other looks like it isn't going to make it.
Everything went well in quarantine, and I moved them into my other aquarium 3 days ago. I suspected that the white dots were either sand or possibly residue from Prime I was putting in the water and they seemed happy and healthy until I moved them. They seemed OK in the main aquarium, they hid alot but were still eating and scavenging in the sand.
However this evening I went to check on them and one was upside down looking quite bloated. It was dead. The other one looks like it has possible buoyancy problems too and I suspect it may be dead by the morning.
There have been no ammonia or nitrite spikes and I acclimatised them slowly. I removed all rocks and anything they might hurt their barbells on in advance, so it definitely wasn't that. All I can think of is that it is stress.
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Sorry to read about this.
I doubt the Prime caused the white dots (based on my own experience of using it), so it's probably more likely your other explanations. I think stress most likely is the cause of the death(s), unfortunately - despite being very careful about transfer, I've had a few fatalities soon after. [I have often wondered if the enhanced water flow in the main tank accounts for it - I've had a few particularly small fish that seem to struggle as though "drowning" from which they don't recuperate.]
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The only 2 variables that were different were the tank mates and the filtration, so the increased flow rate is definitely a possibility. I was using a very gentle sponge filter in the quarantine tank and in the 80 litre it was a large internal filter which created a bit of current. I am tempted to try a sponge filter in my main aquarium as the water flow does seem to stress some fish out and small fish do get stuck behind the filter from time to time!
I think I will have to give up on keeping cories, they seem far too sensitive!
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Sorry to hear that you lost a cory, and that the second looks unwell.
I've generally been quite lucky with my corys, and have not experienced the sort of issues you have had recently, so I don't know what to suggest.
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Unfortunately the other cory died today :(
I thought corys were hardy and easy to keep fish when I bought them. I even went for bronze over panda or albino as I thought they would be hardier. I don't think I will risk getting any more as I have no idea what killed them.
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Sorry to hear this, you really didn’t seem to have much luck with them. I wonder if they had poor genes - some of the most popular species do nowadays...
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Sad news about the second cory.
I can't put my finger on what the problem could be either.