Lethargic Corydoras

Hello All!

First post here. Looking for advice on a juliI cory that hasn’t been doing much the last few days. Details at the bottom.

Tank

What is the water volume of the tank? 180L
How long has the tank been running? 6 weeks
Does it have a filter? Yes, canister
Does it have a heater? Yes, two, one at each end
What is the water temperature? Thermometers at each end read 25.8 and 26.1. One is consistently 0.3 higher than the other.
What is the entire stocking of this tank? (Please list all fish and inverts.)
13 cardinal tetras
5 juliI corydoras
One billion tiny tiny rams horn snails (and a bladder snail or two)

Maintenance
How often do you change the water? Once a week
How much of the water do you change? 1/3 (60L)
What do you use to treat your water? API stress coat +
Do you vacuum the substrate or just the water? Light/spot vacuuming, the pool filter sand substrate looks very clean

*Parameters - Very Important
Did you cycle your tank before adding fish? Yes
What do you use to test the water? API liquid test kit
What are your parameters? We need to know the exact numbers, not just “fine” or “safe”.

Ammonia: 0
Nitrite: 0
Nitrate: <10
pH: 6.8

Feeding
How often do you feed your fish? Once but occasionally twice a day
How much do you feed your fish? Too much. As of yesterday, we are cutting back. We were doing about two small pinches of crushed API tropical flakes, two small pinches of probiotix new life spectrum small pellets, three API shrimp pellets, and then half an API algae tablet maybe once every two days.
What brand of food do you feed your fish? See above
Do you feed frozen or freeze-dried foods? No

Illness & Symptoms
How long have you had this fish? 17 days
How long ago did you first notice these symptoms? A couple days ago
In a few words, can you explain the symptoms? Seems apathetic/lethargic, not moving around much. Small and thin. Gills possibly a little red?
Have you started any treatment for the illness? No
Was your fish physically ill or injured upon purchase? No
How has its behavior and appearance changed, if at all? Become more lethargic

Explain your emergency situation in detail. (Please give a clear explanation of what is going on, include details from the beginning of the illness leading up to now)

We got this fish 17 days ago, on a Sunday, in a batch of 6 juliI corys and one bristlenose. We noticed the next day that one cory was barely moving, except when it went to the surface for a breath, which was a bit often. It was also pretty thin, and it’s top fin wasn’t all the way up. That fish died on the Wednesday. On the Friday, one of our previously purchased cardinal tetras died— rapid decline, gasping at the surface, etc. Noticed it had some tiny spots on it. We figured out this was ich, and on Saturday started treating with Blue Planet Tri-Sulfa. Many of the remaining tetras had a few tiny ich spots, no signs on the corys.

We looked over photos of the fish when we bought them and realised— now that we knew what we were looking for— that our spotty bristlenose wasn’t just naturally spotty but was also heavily infected with The photo was from two hours after we bought it. We hadn’t seen the bristlenose in a few days— thought it was just hiding— but now, fearing the worst, we pulled the tank apart and found it had been dead for several days. All during this time, there was no ammonia spike.

We kept treating with tri-sulfa through the following week. On Thursday, we couldn’t see any more ich, and ammonia was still zero— on Friday night, it was 1. Did a 30% water change. On Saturday morning, ammonia was back up to 1– did another 30% water change and added a lot of liquid beneficial bacteria. On Sunday, ammonia was still up— about 0.75. Fish store guy suggested putting carbon in the medication for a few hours before adding more bacteria. We did this, and within two hours of adding bacteria this time, ammonia was down to 0.25 (without a water change). By the next morning, Monday, it was 0 again. During the ammonia spike, fish behaviour continued as normal, except possibly some had reddish gills. However, the smallest and thinnest of the corys became quite lethargic, moving from time to time but not snuffling around with/like the others. His top fin isn’t all the way up.

Today is Tuesday and the tiny Cory is still lethargic and apathetic when his boisterous buddies snuffle around him. He doesn’t show interest at feeding time. His gills are possibly still a bit red, hard to tell if it’s normal. We are worried he is going the same way as the first cory that died, although he hasn’t been going to the surface to breathe like that one did. The other four corys are large and energetic, so this one’s behaviour stands out. Although he is thin, I don’t think his belly is sunken.

I’ll see if I can get a picture, haven’t been able to get a useful one so far.

Appreciate any advice!

Should add that tiny cory also looks a bit dull in colour compared to his buddies, who have a pearly shimmer to them.

 

He may be a weaker fish and is taking more time to recover. Keep up the water changes and monitoring the parameters. You are doing good there.

Just caution with medicating with cories, since theyre considered scaleless fish and are sensitive to many medications. Its often advised to half dose if needed.

With ich, raising the temps up for 2 weeks past 86F (sorry not good with Celsius despite being canadian) usually is the best cure for it, meds being last resort. Some use salt, but salt also cannot be used with cories either.

 

Thanks very much for your response.

Our local store recommended the tri-sulfa, they said they use it on pretty much all the fish they get in, including corys (many medications available in other countries are not available here in Australia). Another store (the one that sold us the ich-y bristlenose) had recommended a half dose of the tri-sulfa, but this store (which quarantines all their fish themselves) disagreed.

I’ll keep the temperature thing in mind for next time (fingers crossed there is no next time!).

I hope he’s just taking time to recover. Although my partner disagrees about when the illness (?) started, he reckons the cory has been like this since before the ammonia spike.

Managed to get a decent picture.

Thanks heaps for the advice!

 

Welcome to FishLore! I hope you find the site helpful.

 

Welcome to FishLore! I hope you find the site helpful.

Thank you!


I’ve noticed something a bit...weird looking. I didn’t see it in real life, but I can see it in all the zoomed in photos. Anyone have any thoughts on this? Looks like something on its skin?

The fish has gone up to the surface for a breath a few times, in between not doing anything. Still not reacting to other corys snuffling right over it. This is what the other cory was doing before it died We are going to bed expecting the worst

 

My eyes aren’t the best but that looks like it could possibly be an argulous louse, hopefully someone with sharper eyes can take a look, does it move at all?

 

My eyes aren’t the best but that looks like it could possibly be an argulous louse, hopefully someone with sharper eyes can take a look, does it move at all?

Thanks, that’s a good suggestion. I just did some googling and tried to get a closer look, I don’t *think* it’s that.

I managed to get a photo of his other side, he’s got dark spots there too. And you can notice the difference in his colour and the other cory’s.

 

Can you get Seachem Prime? Itll help neutralize any ammonia and nitrite and can help him have an easier time recovering

 

Can you get Seachem Prime? Itll help neutralize any ammonia and nitrite and can help him have an easier time recovering

Not sure if it’s available here but could have a look. Do you think it would make a difference, given our ammonia and nitrite levels are already at zero? We do already use stress coat in the water.

Things seem to have taken a turn, hopefully for the best, late this morning— he is being active for the first time in days. He was actually swimming back and forth in the mid level of the tank for a while. Still not hanging out with the other corys or snuffling properly (wiggling in place but
not rooting through the sand) but a lot more movement than previously. I wonder if he is on the mend from whatever it was? There does still look like there is something wrong with his skin but I feel like surely the increased movement must be a good thing?

Thanks again for the help, it is really appreciated

 

Tbh he looks skinny, like his skin is stretched over bone. That could be a parasite issue or even genetic...

You could soak some pellets in garlic juice and see if that entices him to eat

 

Tbh he looks skinny, like his skin is stretched over bone. That could be a parasite issue or even genetic...

You could soak some pellets in garlic juice and see if that entices him to eat

Thanks for your advice. We thought you might be right about parasites, and the aquarium shop guy agreed. We started treating the tank with a praziquantel based medicine (Blue Planet Fluke & Tapeworm). Although the bottle said use with caution with corydoras, I found people online saying it hadn’t hurt theirs, so we used full strength. He still wouldn’t eat— we tried your idea of food soaked in garlic but no luck. He just sat there with the food right next to him. Other fish enjoyed it though.

Not sure if it wasn’t the right med or if he was just too far gone. This morning he was lying on his side panting, and the tetras had shredded his tail. We figured at this point that it was kinder to euthanize him, and did. RIP tiny cory.

In case anyone else finds this thread and is worried about praziquantel and corydoras like we were— none of our healthy corydoras (or snails and tetras) seemed to have any adverse effects. After two days of treatment, all the other tank inhabitants still look good/normal.

Sad ending but glad he isn’t suffering any more at least

 

Thanks for your advice. We thought you might be right about parasites, and the aquarium shop guy agreed. We started treating the tank with a praziquantel based medicine (Blue Planet Fluke & Tapeworm). Although the bottle said use with caution with corydoras, I found people online saying it hadn’t hurt theirs, so we used full strength. He still wouldn’t eat— we tried your idea of food soaked in garlic but no luck. He just sat there with the food right next to him. Other fish enjoyed it though.

Not sure if it wasn’t the right med or if he was just too far gone. This morning he was lying on his side panting, and the tetras had shredded his tail. We figured at this point that it was kinder to euthanize him, and did. RIP tiny cory.

In case anyone else finds this thread and is worried about praziquantel and corydoras like we were— none of our healthy corydoras (or snails and tetras) seemed to have any adverse effects. After two days of treatment, all the other tank inhabitants still look good/normal.

Sad ending but glad he isn’t suffering any more at least

I'm sorry for your loss, but you made the kindest decision. At that point, there was no bringing him back and you did all you could

 

Sorry to hear.

 

I have recently noticed one of my 3 corydoras has been acting lethargic no other fish in the tank has been hes staying in one spot and when he does move he seems to not be able to swim well
The tank is 29 gallons
it has 7 Dalmation mollies 2 adults and 5 unexpected fry
4 cherry barbs
3 corydora catfish
The parameters are:
Ammonia: 0ppm
Nitrite: 0ppm
Nitrate: 0.1 ppm
PH: 7.6ppm

 

He looks thin. Have you seen him eat? He may be lethargic due to internal parasites. Are you feeding them catfish pellets or algae wafers?

 

He looks thin. Have you seen him eat? He may be lethargic due to internal parasites. Are you feeding them catfish pellets or algae wafers?

Pellets since we have gotten them I am unsure if he has been eating I tend to see the mollies go after the 9ellets instead of their food

 

Just make sure the pellets are 40-50% protein. Cories can starve on algae pellets as they are carnivores. I would probably treat for parasites. If there isnt a cave you could add one and put the food inside it to try to keep it away from the mollies.

 

Just make sure the pellets are 40-50% protein. Cories can starve on algae pellets as they are carnivores. I would probably treat for parasites. If there isnt a cave you could add one and put the food inside it to try to keep it away from the mollies.

They are mainly protein I will be placing the mollies food on the other side of the tabk while I put the pellets where he is the others look fatter so he's definitely thin

 

The substrate is my main concern

 

The substrate is my main concern

The way it looks or the type of substrate I vacuum it quite frequently with the water changes however I'm always looking for advice to better my aquariums

 

Cories spend much of their time digging through substrate looking for food morsels. Because of that it is usually recommended they have sand or very smooth rounded gravel. This protects their barbels from cuts and possible infection. The problem with the gravel even if they are rounded is that they can get food trapped underneath in air pockets that cories cant get to and sulphur can build up causing issues. Long story short---sand is recommended for cories.

 

Cories spend much of their time digging through substrate looking for food morsels. Because of that it is usually recommended they have sand or very smooth rounded gravel. This protects their barbels from cuts and possible infection. The problem with the gravel even if they are rounded is that they can get food trapped underneath in air pockets that cories cant get to and sulphur can build up causing issues. Long story short---sand is recommended for cories.

Thank you we actually had sand in there before getting the fish but heard it wasn't good but it may have been the sand we used wjat type of sand is recommended?

 

The size and shape is the issue.
Leftover food will get trapped / unreachable and cause pollution (ammonia/nitrites and bacterial)
Temporary sollution is a sandbeach.
Don't know if this is culprit but it could be.

 

The size and shape is the issue.
Leftover food will get trapped / unreachable and cause pollution (ammonia/nitrites and bacterial)
Temporary sollution is a sandbeach.
Don't know if this is culprit but it could be.

What type of sand is best to not be harmful to them and would it be better for us to move him Into a smaller tank by himself to have him eat and see if that helps?

 

Cories are social so I doubt he would enjoy being by himself. Any type of sand works really as long as you rinse it well enough. Some use the sand substrate from fish stores, others play sand, and some get pool filter sand. They are all different sizes- just remember the smaller the granules the tighter it compacts so you may have to stir it once in a while to get gases from building up under the top layer.

 

Cories are social so I doubt he would enjoy being by himself. Any type of sand works really as long as you rinse it well enough. Some use the sand substrate from fish stores, others play sand, and some get pool filter sand. They are all different sizes- just remember the smaller the granules the tighter it compacts so you may have to stir it once in a while to get gases from building up under the top layer.

So for changing the substrate do I leave the fish in while I change it or how would I change it to sand

 

I would start slowly. Both for stress and for your BB. Take a 1/4 or so of the old gravel out and replace it with well-rinsed sand. Then wait several days to a week to do some more. Some people only do 1/2 sand and half gravel but it depends on the tank.

 

There was still some sand in the tank but had gravel over ot so until I can get sand I have moved the gravel making like a beach area hes still alive just sitting in the sand moving sometimes I will feed them there for now