Mystery disease only affecting cories

[jessicaspeigel]

Hey friends,

I’ve been struggling with a mystery disease that’s only affecting Cories. I’ve lost 3 over the last two months and the last death was 3 weeks ago.

Everyone seems healthy now (attached a vid of the 5 cories left). My worry is that their school is really small now (went from 8 to 5), so I want to add some more but am hesitant until I’ve identified the issue. 

Background

The tank is a 55g freshwater planted community tank with 5 false julii cories, 20 cardinal tetras, 4 otos, and a boatload of shrimps (amanos and cherries). The tank is about 6 months old.

Params:

Temp: 74.5 / Ammonia: 0 / Nitrite: 0 / Nitrate: 5 / pH: 7.2 / Gh: 80 / Kh: 120 / Chlorine: 0

The issue 

About a month ago, one of the cories had swim bladder issues. I tried feeding peas and an epsom salt bath but unfortunately I lost him. 

Fast forward to three weeks ago. I found one cory dead and another with his tail floating up. I’d been super sick for the last two days after a work trip, so I didn’t see if the one that passed had swimming issues, so that is an assumption on my part. I gave the one with swimming issues epsom salt dips over a day or two and it seemed to help a bit but I lost him. Is there something that would cause swim bladder issues in cories but none of the other fish? My water quality is unchanged and I’ve got masses of shrimp babies.

Possible cause?

I don’t overfeed but I’m curious if maybe the way I feed is causing problems. I only feed every 2-3 days to try and keep my snail population at bay and I’m wondering if it’s possible that because they’re hungry, they’re gorging and getting digestive issues. I fed on Thursday when I got home from my travel and had the death right after. 

Anyone have any ideas? I posted on Reddit and didn’t get any help. I changed my feeding habit to smaller amounts every day and everyone seems happy although I did have a gap between the first and second deaths as well. 

for some reason I can’t attach video, so here’s a Dropbox link. 

Edited November 11, 2023 by jessicaspeigel
Fixed links

[Colu]

How long have you had the Cory's before the first death any rapid breathing hanging out near the surface lethargy flashing spitting food erratic swimming sunken belly @jessicaspeigel

[jessicaspeigel]

I think three or four months? I had cycled the tank with plants and added fish slowly when I saw plant growth and only nitrates. The Cories were the first ones I added. 

I do still have video and a photo of my first little guy to have issues. It happened really fast. I noticed he was having slight issues swimming (vid) but then within 4 hours, he was unable to remain upright, stuck on his side (see attached photo), corkscrew swimming. He died the next day. It was a similar story with the next one.

The swim bladder issues were the only visible problem. No lethargy, eating well, no gasping, distended belly, clamped fins or any other injuries. That’s why I was wondering if maybe I was causing digestive issues with my feeding schedule. I’ve always worried far more about feeding too much than too little.

 

 

[Colu]

On 11/12/2023 at 4:49 PM, jessicaspeigel said:

I think three or four months? I had cycled the tank with plants and added fish slowly when I saw plant growth and only nitrates. The Cories were the first ones I added. 

I do still have video and a photo of my first little guy to have issues. It happened really fast. I noticed he was having slight issues swimming (vid) but then within 4 hours, he was unable to remain upright, stuck on his side (see attached photo), corkscrew swimming. He died the next day. It was a similar story with the next one.

The swim bladder issues were the only visible problem. No lethargy, eating well, no gasping, distended belly, clamped fins or any other injuries. That’s why I was wondering if maybe I was causing digestive issues with my feeding schedule. I’ve always worried far more about feeding too much than too little.

 

 

How often are you feeding and what foods are feeding 

[jessicaspeigel]

I was feeding 2-3 times a week to try and control my snail population and after I realized that maybe the cories weren’t getting enough (after the last death about 3 weeks ago), I upped that to every day but less food. I feed frozen foods, daphnia, baby brine shrimp, cyclops. Depending on the size of the cube, I’m doing one over 2 or 3 days. I also feed the shrimp their little shrimp pellets but the fish try and eat those too. 

I need to add some veggies to the mix. 

[Colu]

On 11/12/2023 at 10:05 PM, jessicaspeigel said:

I was feeding 2-3 times a week to try and control my snail population and after I realized that maybe the cories weren’t getting enough (after the last death about 3 weeks ago), I upped that to every day but less food. I feed frozen foods, daphnia, baby brine shrimp, cyclops. Depending on the size of the cube, I’m doing one over 2 or 3 days. I also feed the shrimp their little shrimp pellets but the fish try and eat those too. 

I need to add some veggies to the mix. 

It could be  their getting outcompeted by your cardinal tetras and  didn't get enough food and became weak what I would do is feed them a small pellet food once a day such as hikari micro pellet  along side  the frozen food you can add repashy super green for your Otto and your Cory's will also eat it when i have kept Cory's in the past I have always feed them twice a day to make sure there not getting outcompeted  when you have fish that eat quickly such as tetra or barbs very little food will make it to the bottom i would monitor them for next couple of weeks with the increased feeding then give an update nothing else is just out at me disease wise given the time between deaths and no deaths amongst your tetras 

[jessicaspeigel]

Makes sense. After I realized I might be underfeeding, I couldn’t believe how I hadn’t seen it before. The other thing about the Cories is that, while adorable, they don’t seem super bright about noticing food. I have some hikari pellets but they never found them. I’ll try them again though and grab some super green and also start supplementing with blanched veggies. 

Thanks for the help. I was pretty sure it was the feeding, but wanted a gut check that there wasn’t something I was missing. The only other thing I could think of was that I was afraid to vacuum after the shrimplets showed up, so maybe the Cories, being hungry, were rooting around and found an ammonia pocket or something. It just seemed so weird that it was only affecting them and no one else. 

[nabokovfan87]

On 11/11/2023 at 2:57 PM, jessicaspeigel said:

Everyone seems healthy now (attached a vid of the 5 cories left). My worry is that their school is really small now (went from 8 to 5), so I want to add some more but am hesitant until I’ve identified the issue. 

In the video they look good!  I would expect them to spawn for you and that would increase the numbers over time.  I wouldn't be concerned much at all of adding to the herd at this point.  Give them time to grow and just do their thing.
 

On 11/11/2023 at 2:57 PM, jessicaspeigel said:

Temp: 74.5 / Ammonia: 0 / Nitrite: 0 / Nitrate: 5 / pH: 7.2 / Gh: 80 / Kh: 120 / Chlorine: 0

Getting GH higher than KH might be helpful.  It's a ratio used and recommended for plants.  Just a sidenote and something to keep an eye on if the GH drops further.
 

On 11/11/2023 at 2:57 PM, jessicaspeigel said:

I only feed every 2-3 days to try and keep my snail population at bay and I’m wondering if it’s possible that because they’re hungry, they’re gorging and getting digestive issues. I fed on Thursday when I got home from my travel and had the death right after.

At minimum feed once a day.  Preferably twice whenever you have a day where you want to feed them again in the afternoon (2-3x a week) is always fine too.  I tend to use repashy or something and then let that sit in the tank for them to graze on.  the same thing works in the afternoon and they can feed through the night.  One thing to keep in mind with both the shrimp and the fish is the substrate that you have.
 

The food might end up being too hard to them to get to if it falls down in the crevices.  It just depends on what you're feeding.  It's also a good thing for the shrimp too and they get to have their fill a bit easier when it comes time to feed them calcium based foods.

Adding a snail issue on top of all of those things means that any food that isn't in the dish, then you'll end up with that being very accessible for the snails and that might make issues worse for you.  That's a roundabout way to simply say, having some dishes for the shrimp to feed on, using a feeding plate (or having a sand section) for the corydoras could be helpful to control the snails and make sure food is indeed eaten.

Give the tank a good cleaning, use some snail traps, and just repeat that until you're satisfied with the progress.
 

On 11/12/2023 at 2:05 PM, jessicaspeigel said:

I was feeding 2-3 times a week to try and control my snail population and after I realized that maybe the cories weren’t getting enough (after the last death about 3 weeks ago), I upped that to every day but less food. I feed frozen foods, daphnia, baby brine shrimp, cyclops. Depending on the size of the cube, I’m doing one over 2 or 3 days. I also feed the shrimp their little shrimp pellets but the fish try and eat those too. 

I need to add some veggies to the mix. 

corydoras usually do well with a mix of krill / spirulina granules, pellets, or flakes as long as they don't have something that too big for them to digest.  Algae wafers might not be a bad idea, repashy would be good for them too and you can try a variety of the recipes available.  Bug based foods like aqueon nutrinsect are pretty good and most corydoras seem to love some bugs!  While omnivore food is good for corydoras, just keep in mind they do need some good protein sources as well.

 

[jessicaspeigel]

On 11/12/2023 at 3:54 PM, nabokovfan87 said:

In the video they look good!  I would expect them to spawn for you and that would increase the numbers over time.  I wouldn't be concerned much at all of adding to the herd at this point.  Give them time to grow and just do their thing.

That’s great to hear! Yeah, I’m hoping for babies. I had a spawning pair of angels years ago and it’s so fun. I’m pretty sure I’ve got two females and three males which is a great ratio at least. Fingers crossed!

 

On 11/12/2023 at 3:54 PM, nabokovfan87 said:

Getting GH higher than KH might be helpful.  It's a ratio used and recommended for plants.  Just a sidenote and something to keep an eye on if the GH drops further.

Yeah, I’ll keep an eye on it. It’s very stable at least. I live in Seattle and our water out of the tap is so soft. Literally 1 drop of kh and gh reagent to turn colors. I have a bunch of rocks in my tank and kept an eye on it as it was cycling before I added fish and this is where it settled so I haven’t messed with it. 

 

On 11/12/2023 at 3:54 PM, nabokovfan87 said:

That's a roundabout way to simply say, having some dishes for the shrimp to feed on, using a feeding plate (or having a sand section) for the corydoras could be helpful to control the snails and make sure food is indeed eaten.

I think you’ve hit the nail on the head. When I was setting this tank up I grabbed ecocomplete because it’s my favorite but am regretting not doing a sand layer on top. Most of the food goes right through. I’ll pick up a couple feeding dishes. And snail traps. I just don’t like killing them but I read freezing is pretty humane at least. 

 

On 11/12/2023 at 3:54 PM, nabokovfan87 said:

Algae wafers might not be a bad idea, repashy would be good for them too and you can try a variety of the recipes available.  Bug based foods like aqueon nutrinsect are pretty good and most corydoras seem to love some bugs!

Gonna try all this, thank you!