I have bad luck with Coris...

[Hokieokieamy]

Hey all,

I have bad luck with Coris, they always want to die on me. I just had one die and I couldn't see any discoloration on it but it became really sluggish over the past few days and would lie sideways a lot and would, in general, not move a lot. It died today. Another one of my coris now has a weird orange-tint to its fins, which I have never seen before. All my other fish are doing just fine and I never have any issues with them (besides my killfish recently which was an odd occurrence).

I checked the ammonia, nitrate, nitrite levels in my fish tank and it's all normal. My pH was around 7.3ish (I cant remember the exact number). I have slightly harder water (I will need to check the exact # again as it's been awhile) but I have heard Coris can adapt well to hard water.

My only thought is that they are getting a bacterial infection somehow? I try to keep my tank clean and do a 50% water refill each week but I will admit, it seems like I can never get all of the poop out of the tank. Otherwise, the sand is free of debris. Another thing I might start doing is sifting the sand with my fingers when cleaning to try and unearth some extra fecal matter to do a more thorough cleaning.

Does anyone have any advice? I don't want to give up on my cory rearing because I love them so much, but it may come to that if I continue to have issues

Thank you

 

[CassCats]

What species of cories?

What is your GH?

Also, what are the numbers for your ammonia, nitrite, and nitrate?

Do you have photos? They would help

 

[Colin_T]

How long after you get the fish, do they die?
You could be buying sick fish.

If you have sand, then it's a good idea to run your fingers through open areas of sand each week to help loosen it up and reduce the chance of anaerobic pockets forming under it.

 

[mbsqw1d]

Fish can't adapt to the water hardness unfortunately. Its just part of their DNA whether they are soft/hard water dwellers. Whilst providing cories hard water won't kill them instantly, it causes damage to their organs over time

 

[Hokieokieamy]

What species of cories?

What is your GH?

Also, what are the numbers for your ammonia, nitrite, and nitrate?

Do you have photos? They would help

Corydoras and I am not home at the moment but when I am, I will check the numbers and let you know

 

[Hokieokieamy]

How long after you get the fish, do they die?
You could be buying sick fish.

If you have sand, then it's a good idea to run your fingers through open areas of sand each week to help loosen it up and reduce the chance of anaerobic pockets forming under it.

Hey Colin,

It's a little while after I buy them, it's enough time where they grow a decent size and then die

 

[Hokieokieamy]

Fish can't adapt to the water hardness unfortunately. Its just part of their DNA whether they are soft/hard water dwellers. Whilst providing cories hard water won't kill them instantly, it causes damage to their organs over time

I understand, I have heard both sides saying they can adapt and that they cannot. But maybe you are right since I have had so many issues with them and not my other fish, which are supposed to do well in a hard water tank

 

[AdoraBelle Dearheart]

Corydoras and I am not home at the moment but when I am, I will check the numbers and let you know

There are at least 142 different species of corydora. Different species have different requirements in terms of tank size, temperature, and GH, so we need to know which type of corydora. When you upload photos, someone will be able to ID them for you if you're not sure what you have

 

[Hokieokieamy]

There are at least 142 different species of corydora. Different species have different requirements in terms of tank size, temperature, and GH, so we need to know which type of corydora. When you upload photos, someone will be able to ID them for you if you're not sure what you have

One is spotted and grows to a max of about 2 inches and the other is the same in terms of growth but is an albino corydora. I did have two more because I know they are schooling fish but those two both died recently

 

[AdoraBelle Dearheart]

One is spotted and grows to a max of about 2 inches and the other is the same in terms of growth but is an albino corydora. I did have two more because I know they are schooling fish but those two both died recently

Would you be able to share photos of them later? NC is great at telling which species albinos are, and she knows cories better than anyone here.

There are some species of cory that cope better with harder water than others, so if you also find out your GH, we might be able to recommend some different species that could work for your water. But photos of the current ones will help for ID puposes.

 

[Hokieokieamy]

Thank you everyone for your patience. I got my readings and they are:
Water hardness: GH of 143.2 ppm
pH: 7.4
Ammonia: 0
Nitrite: 0
Nitrate: 40

Also, attached is a picture of one of my coris with the orange tint on his fins, which I believe is new because I never noticed it before? He’s acting normal so far. I couldn’t find my albino Cory but he’s the same size as the Cory pictured, just white.

 

[CassCats]

Thats a corydoras sterbai, your GH is fine. You have relatively soft water in terms of fishkeeping.

However your nitrates are very high and this would contribute to losing cories.

Do daily water changes until that number is below 20, even better below 10.

 

[Naughts]

Thank you everyone for your patience. I got my readings and they are:
Water hardness: GH of 143.2 ppm
pH: 7.4
Ammonia: 0
Nitrite: 0
Nitrate: 40

Also, attached is a picture of one of my coris with the orange tint on his fins, which I believe is new because I never noticed it before? He’s acting normal so far. I couldn’t find my albino Cory but he’s the same size as the Cory pictured, just white.

Orange pectoral fins is natural colouration for sterbai.

What type of sand do you have? It looks ok but the cory's barbels look short and sharp sand can damage the barbels.

 

[AdoraBelle Dearheart]

Thank you everyone for your patience. I got my readings and they are:
Water hardness: GH of 143.2 ppm
pH: 7.4
Ammonia: 0
Nitrite: 0
Nitrate: 40

Also, attached is a picture of one of my coris with the orange tint on his fins, which I believe is new because I never noticed it before? He’s acting normal so far. I couldn’t find my albino Cory but he’s the same size as the Cory pictured, just white.

I also see a seashell in the pic. Those leech calcium into the water and affect your water hardness and pH, not a good idea in a tropical tank. While your hardness is okay for your stock right now, with things like seashells in the tank changing the hardness, each water change is going to cause a slight fluctation, and we don't want fluctuations, stable is always better.

 

[Hokieokieamy]

Thats a corydoras sterbai, your GH is fine. You have relatively soft water in terms of fishkeeping.

However your nitrates are very high and this would contribute to losing cories.

Do daily water changes until that number is below 20, even better below 10.

Thank you! Will daily water changes work though if I have tap water? I add a solution to it to reduce anything harmful in it, but I’m still afraid that could affect nitrate levels.