Cories keep dying

[DonkeyCheese]

Corydora keep dying. Only having problems with the cories. First time I lost 2 after being in the tank for about 3 weeks but that was from them getting stuck between rocks so I redid the scape. Another time was a loss after a stressful egg laying session. Another time was the runt of the pack who probably got bullied/stressed. Another time no clue. I try to maintain a group of 12 but never seems to work out.

Well established heavily planted 90 gallon tank with sand bottom. Plenty of nooks/crannies/hiding spots. Probably a good 3 or 4 inches of plants to every inch of fish. Angelfish, keyhole cichlids, black neons, and tons of snails all of which are very happy and never lost any of them over the life time of the tank. Well, 1 neon got wedged behind the heater but that’s his fault for being dumb. Running with plenty of filtration and on top of maintenance. Temp running76-77. I have 2 air stones in there as well. No chlorine and no ammonia issues. Ph arguably between 7 and 7.4 depending on who’s eye but regardless it stays consistent which is what matters. Nitrites are zero and nitrate doesn't go above 10ppm or below 5ppm. I do small water changes, usually two per week, 3 if it really needs it but not often. Never been a fan of 1 large water change. In my opinion I think it helps with overall tank stability with a less drastic change in conditions like a large one does. However, if something catastrophic happened and the system was crashing then larger water for sure.

They eat whatever the big guys miss but they also get their own food and a variety to boot. Omega sinking shrimp pellets, hikari algae wafer, bloodworms, bug bites. They get some during the day when the other fish are fed but I also come back to give them their own food right before it’s lights out.


What can I do to possibly correct this trend?

[starfish615]

Hmm can I ask what type of Cory you have been trying to keep? No other large bottom feeder in tank like Pleco etc? Sounds like you have a good amount of hiding spots but you ever notice the cichlid or angles harassing them? I have found that Cory do not handle stress well. I also was unsuccessful trying to keep them with cichlids myself but it was years ago and I will admit I didn’t know much back then lol

[Colin_T]

Pictures and video of the fish and the entire tank so we can check them for diseases and abnormal behaviour?
You can upload videos to YouTube, then copy & paste the link here.
If you use a mobile phone to film the fish, hold the phone horizontally so the footage fills the entire screen.

Check pictures on your computer before posting and make sure they are clear and in focus.

-------------------

What sort of filter is on the tank?
How often and how do you clean the filter?

Do you gravel clean the substrate when you do water changes?
So you dechlorinate the new water before adding it to the tank?

What is the GH (general hardness) and KH (carbonate hardness) your water supply?
This information can usually be obtained from your water supply company's website or by telephoning them. If they can't help you, take a glass full of tap water to the local pet shop and get them to test it for you. Write the results down (in numbers) when they do the tests. And ask them what the results are in (eg: ppm, dGH, or something else).

-------------------

Runts (fish that don't grow as fast as the others) are usually suffering from intestinal worms or have a genetic defect.

Do you feed the fish any frozen or live foods?

[DonkeyCheese]

Ive kept albino, bronze, sterbai, juli, peppered, and panda, I’ve kept them in 20 gallons, 40 breeders, 55, and most recently my 90. Best luck I had was species only while breeding.

The angelfish are great with them. No signs of fin nipping or overall aggression. There’s an occasional “get out of my way” since cories do not understand how to travel around a tank and just do and go wherever. Besides that the angels don’t even notice them. As far as keyholes, they shouldn’t even be called cichlids. They are more like big dumb mollys then a Cichlid. They are not big either, around 4in. Probably one of the friendliest fish I’ve kept. Exact opposite of what you would think a cichlid is. Of course they can and will still act differently for others and are still a cichlid but nothing like the other cichlids out there.

I’ve kept corydora in a rainbowfish tank. I’ve kept in a swordtail tank. I did honey gourami at some point. I’ve done small community with stuff like harlequin rasbora* and rummys. Had issues in all of them.*Best tanks I’ve had for them was a 20 long shrimp tank and solo tank when *breeding.

Is there a different bottom feeder you’d suggest? Dwarf chain loach, yoyo loach, Pictus?

[Aiken Drum]

It looks to me that you have had 4 seperate incidents, 3 of which you have identified the cause of death and they are unrelated.

There doesnt appear to be anything obviously wrong with what you are doing and no common cause with the deaths.

Just bad luck.

[m.j.gomez]

Originally Posted by DonkeyCheese

Corydora keep dying. Only having problems with the cories. First time I lost 2 after being in the tank for about 3 weeks but that was from them getting stuck between rocks so I redid the scape. Another time was a loss after a stressful egg laying session. Another time was the runt of the pack who probably got bullied/stressed. Another time no clue. I try to maintain a group of 12 but never seems to work out.



Well established heavily planted 90 gallon tank with sand bottom. Plenty of nooks/crannies/hiding spots. Probably a good 3 or 4 inches of plants to every inch of fish. Angelfish, keyhole cichlids, black neons, and tons of snails all of which are very happy and never lost any of them over the life time of the tank. Well, 1 neon got wedged behind the heater but that’s his fault for being dumb. Running with plenty of filtration and on top of maintenance. Temp running76-77. I have 2 air stones in there as well. No chlorine and no ammonia issues. Ph arguably between 7 and 7.4 depending on who’s eye but regardless it stays consistent which is what matters. Nitrites are zero and nitrate doesn't go above 10ppm or below 5ppm. I do small water changes, usually two per week, 3 if it really needs it but not often. Never been a fan of 1 large water change. In my opinion I think it helps with overall tank stability with a less drastic change in conditions like a large one does. However, if something catastrophic happened and the system was crashing then larger water for sure.



They eat whatever the big guys miss but they also get their own food and a variety to boot. Omega sinking shrimp pellets, hikari algae wafer, bloodworms, bug bites. They get some during the day when the other fish are fed but I also come back to give them their own food right before it’s lights out.





What can I do to possibly correct this trend?

Hello, this is just a suggestion but you may want to add something for circulation. Cory's are bottom dwellers & in planted tanks no matter how good you clean there is stuff that gets trapped.
With a power head or wave maker you can dissipate anything that may have a negative affect on them. I'm sure all your fish will benefit from added circulation. Hopefully this helps you!!!!!

[Andy Sager]

Originally Posted by DonkeyCheese

Ive kept albino, bronze, sterbai, juli, peppered, and panda, I’ve kept them in 20 gallons, 40 breeders, 55, and most recently my 90. Best luck I had was species only while breeding.

The angelfish are great with them. No signs of fin nipping or overall aggression. There’s an occasional “get out of my way” since cories do not understand how to travel around a tank and just do and go wherever. Besides that the angels don’t even notice them. As far as keyholes, they shouldn’t even be called cichlids. They are more like big dumb mollys then a Cichlid. They are not big either, around 4in. Probably one of the friendliest fish I’ve kept. Exact opposite of what you would think a cichlid is. Of course they can and will still act differently for others and are still a cichlid but nothing like the other cichlids out there.

I’ve kept corydora in a rainbowfish tank. I’ve kept in a swordtail tank. I did honey gourami at some point. I’ve done small community with stuff like harlequin rasbora* and rummys. Had issues in all of them.*Best tanks I’ve had for them was a 20 long shrimp tank and solo tank when *breeding.

Is there a different bottom feeder you’d suggest? Dwarf chain loach, yoyo loach, Pictus?

There's a couple of things that may be in play. First off, you say you kept all these different varieties and in with all different kinds of set ups yet had problems with them all. If this is true, you need to look at the set ups for water temps, substrates, wild fish/ tank raised ones, etc. Did you lose them all at a similar time or did you lose them from occasional deaths or accidents? Most Corydora cats come from rapid flowing, highly oxygenated water so if you don't have that in your setups, that could be a reason for your failures. ( For example, your honey gourami tank should have had slow moving water which is the opposite of what corydoras need. ) Keeping shoals of corydoras ( or any kind of fish) is not always easy. When you lose a fish here and there, hierarchy issues or too many of one gender issues could have caused these problems. When you lose the fish en mass, that's usually a tank/water caused situation. Certain wild caught species are more prone to diseases ( internal more than external) that may be the issue. Just a lot of possibilities. You really need to dig into the set ups you had for them.

As MJ Gomez suggested, a circulation pump might solve your issues. It might explain why your success(es) came when the fish were by themselves. If your issue is lack of oxygenated water at the bottom, none of the loaches or Pictus you listed would be a good substitute as they all need higher oxygenated water.

Hope this helps.