Strange Phenomenon with Pygmy Cories

[Zeaqua]

Hi all! The first fish I have ever kept in this hobby were Pygmy Corydoras. I had quickly fallen in love after ordering them about 2 years ago, so I bought another shipment from AquaHuna. I noticed after receiving them that one had a missing eye. I named it Popeye, and didn’t assume anything was wrong. I had a few successful breeding attempts, and went on with keeping them. This went on until recently, I noticed that there were actually multiple Popeyes. A few of the younger generations also had singular missing eyes. Could this be a genetic deformity? The only tankmates I had kept them with up until this point were a few cherry shrimp and the occasional endless fry to grow out. I doubt that they could be the culprits, so if this is genetic, should I stop breeding? I’ll try to post some pics when I see the lil guys. 

[Colu]

On 1/22/2024 at 3:01 AM, Zeaqua said:

Hi all! The first fish I have ever kept in this hobby were Pygmy Corydoras. I had quickly fallen in love after ordering them about 2 years ago, so I bought another shipment from AquaHuna. I noticed after receiving them that one had a missing eye. I named it Popeye, and didn’t assume anything was wrong. I had a few successful breeding attempts, and went on with keeping them. This went on until recently, I noticed that there were actually multiple Popeyes. A few of the younger generations also had singular missing eyes. Could this be a genetic deformity? The only tankmates I had kept them with up until this point were a few cherry shrimp and the occasional endless fry to grow out. I doubt that they could be the culprits, so if this is genetic, should I stop breeding? I’ll try to post some pics when I see the lil guys. 

What are your water parameters ammonia nitrite nitrate pH KH GH temperature what are you feeding and how often what filtration are you using if Popeye left untreated can sometimes cause loss of an eye 

Edited January 22 by Colu

[Schuyler]

Just to be clear, the eye is just missing completely, right? You don't see any with an eye bulging out?

Does it look like an open wound or just that there's nothing there?

[Zeaqua]

On 1/22/2024 at 11:13 AM, Colu said:

What are your water parameters ammonia nitrite nitrate pH KH GH temperature what are you feeding and how often what filtration are you using if Popeye left untreated can sometimes cause loss of an eye 

About 20 ppm nitrate, 0 ammonia or nitrite. PH 7.5, water is kept at around 76. Feed a mix of BBS, nano pellets, and frozen daphnia. I feed once daily, not too much. I use a medium coop sponge filter.

On 1/22/2024 at 1:00 PM, Schuyler said:

Just to be clear, the eye is just missing completely, right? You don't see any with an eye bulging out?

Does it look like an open wound or just that there's nothing there?

Yep, the eye is completely gone. Not to be graphic, but there is simply a hollow eye socket covered in scales/skin, seemingly completely healed, or without injury in the first place. I have no clue what it could be apart from those two options. 

[Colu]

On 1/23/2024 at 12:03 AM, Zeaqua said:

Yep, the eye is completely gone. Not to be graphic, but there is simply a hollow eye socket covered in scales/skin, seemingly completely healed, or without injury in the first place. I have no clue what it could be apart from those two options. 

Water parameters are fine your filtration and food  are fine could be genetic it's also possible something underlying is causing the eye loss and they are healing with out you noticing  are the  fish with only one eye is missing the eye  on the same side have you noticed Any flashing if possible can you post a picture 

Edited January 23 by Colu

[Odd Duck]

Typically animals with genetic microphthalmia (smaller than normal eyes) will have a notably smaller socket and may have remnant, abnormal eye still present.  Genetic anophthalmia (no eye at all) will sometimes have a slightly pinched look where the eye should have been.  They won’t have any empty looking socket because socket development needs the globe of the eye being present and developing at the same time to cause the socket to form.

If you’ve ever seen blind cave fish (Astyanax mexicanus - a species of fish that evolved in a cave system in Mexico and lost the need for eyes), they sometimes have a little dark area under the skin where their eye should have been - to me it looks like a touch of residual retina that never proceeded to develop correctly. They sometimes have that slightly pinched or just a “not smooth” look to the skin surface where the eye should have been.  They never have a hollow socket that I’ve ever seen.  The socket just doesn’t develop into a hollow if there’s no globe to fill it.  There are other eyeless or blind cave fish but that’s the one I’m most familiar with.  I don’t know enough about the others to say anything.

Your cories are having eye issues, like popeye, or someone is taking their eyes.  Popeye would be very hard to notice in a crowd of such tiny, sometimes secretive cories.  There’s no way in the world I could identify each of my pygmy cories, let alone tell you if one had popeye and was hiding because of it.  I can’t even count mine accurately.  I have at least 8, could be twice that.  Planted tank and fast little buggers that dodge in and out of the dense Anubias in their tank.  The food tends to go right into the Anubias forest because it goes in at the back of the tank since it’s a cube with the near solid glass lid and the only gap is at the HOB overflow.  🤷🏻‍♀️ 

Could there be a genetic component that is causing them to have eye problems?  Yes.  But empty sockets means there’s some sort of issue or somebody’s being bad.

[anewbie]

Are the pygmy by themselves or in a community aquarium. Some fishes like female dwarf cichild will frequently go for the eye of cory to remove them from their territory.

 

[Zeaqua]

On 1/22/2024 at 8:12 PM, Colu said:

Water parameters are fine your filtration and food  are fine could be genetic it's also possible something underlying is causing the eye loss and they are healing with out you noticing  are the  fish with only one eye is missing the eye  on the same side have you noticed Any flashing if possible can you post a picture 

Sorry about the very late reply! I took some time to get a picture, and when I wasn’t able to as the cories are so elusive, I forgot about this thread. Here’s a picture!

On 1/23/2024 at 1:35 AM, Odd Duck said:

Typically animals with genetic microphthalmia (smaller than normal eyes) will have a notably smaller socket and may have remnant, abnormal eye still present.  Genetic anophthalmia (no eye at all) will sometimes have a slightly pinched look where the eye should have been.  They won’t have any empty looking socket because socket development needs the globe of the eye being present and developing at the same time to cause the socket to form.

If you’ve ever seen blind cave fish (Astyanax mexicanus - a species of fish that evolved in a cave system in Mexico and lost the need for eyes), they sometimes have a little dark area under the skin where their eye should have been - to me it looks like a touch of residual retina that never proceeded to develop correctly. They sometimes have that slightly pinched or just a “not smooth” look to the skin surface where the eye should have been.  They never have a hollow socket that I’ve ever seen.  The socket just doesn’t develop into a hollow if there’s no globe to fill it.  There are other eyeless or blind cave fish but that’s the one I’m most familiar with.  I don’t know enough about the others to say anything.

Your cories are having eye issues, like popeye, or someone is taking their eyes.  Popeye would be very hard to notice in a crowd of such tiny, sometimes secretive cories.  There’s no way in the world I could identify each of my pygmy cories, let alone tell you if one had popeye and was hiding because of it.  I can’t even count mine accurately.  I have at least 8, could be twice that.  Planted tank and fast little buggers that dodge in and out of the dense Anubias in their tank.  The food tends to go right into the Anubias forest because it goes in at the back of the tank since it’s a cube with the near solid glass lid and the only gap is at the HOB overflow.  🤷🏻‍♀️ 

Could there be a genetic component that is causing them to have eye problems?  Yes.  But empty sockets means there’s some sort of issue or somebody’s being bad.

Very interesting! With closer inspection from the picture, it may be possible that the cories simply have flesh-colored eyes on one side, or that they are hollow. Either way, do thing that those affected are half-blind, as they do not react to my movement when facing that way, while the rest of their school does. 

On 1/23/2024 at 7:38 AM, anewbie said:

Are the pygmy by themselves or in a community aquarium. Some fishes like female dwarf cichild will frequently go for the eye of cory to remove them from their territory.

 

They’ve nearly always been in a species tank (with the exceptions of shrimp and snails) but I have kept them with small endler’s and tetras in the past. 

[Odd Duck]

Is that Cory missing the other eye, also?  It looks like it could be with that center part looking brighter.  The inside of their eyes are not far apart so if they are missing both eyes, there can be light coming through the very minimal separation between the sockets.  If that is a hollowed out socket, there isn’t an underdeveloped eye, it’s missing completely.  That doesn’t look like an underdeveloped eye to me.  So missing globe usually means somebody is removing them or there is infection causing eventual loss.