Hi, I have a 4 month old 70l tank. I had 6 albino cories but sadly one died soon after arrival. All other fish have done fine and the water parameters are good. Until recently I noticed particularly on the larger two of my cories they are looking very orange. On closer examination I think their scales have peeled away. I am really sad about it as I've tried so hard to give them all a good and safe environment after knowing nothing about fish keeping at the start. Can anyone offer any insight? Anything I can do to help them? Thank you
Infection?
- Thread starter Elena82x
- Start date
In case it helps, PH is about 7. Ammonia and nitrite 0, nitrate 20 typically. I have a good quality filter and heater that came with the tank. I feed them twice a day usually spirulina sinking wafers, weekly frozen bloodworm and peas. Tank slightly overstocked due to molly fry in separation box whilst I wait for new 240l to cycle. I've been doing approx 20% water change every two days. 3 mollies, 8 fry, 6 guppies 5 cory catfish and some uninvited snails. Behaviourally the cories are mostly ok though get a bit giddy in the evenings which made me wonder if something wrong even before noticing the scales issue.
They're often more active in the evenings, like to swim about in a big group? That chunky female in the first pic looks as though she might be full of eggs, so the activity you're seeing might be pre-spawning behaviour. If you see the smaller, slimmer cories following the larger, chunkier ones around, that's normal pre-spawning behaviour. 
Glad you're upgrading the tank to a good sized one, you've seen that the current one is a bit too small for this amount of fish, and for C. aeneus, the cories you have, they can get pretty big before you know it!
What substrate do you have them on? For now, I'd recommend increasing the volume of the water changes. Change 40-50% every other day. If there are missing scales, that does leave them at risk of a secondary infection - hard to see from the photos if there's an infection - but if it gets fluffy or looks worse, post more pics and more action would be needed. But for now, increased water changes would help, the clean fresh water and cleaning the substrate reduces harmful organisms in the tank that could cause an infection, and boosts the fishes immune systems so they stand the best chance of healing and fighting off any secondary infections.
So which substrate do they have? And is there any decor they could be scraping against when hiding?
Glad you're upgrading the tank to a good sized one, you've seen that the current one is a bit too small for this amount of fish, and for C. aeneus, the cories you have, they can get pretty big before you know it!
What substrate do you have them on? For now, I'd recommend increasing the volume of the water changes. Change 40-50% every other day. If there are missing scales, that does leave them at risk of a secondary infection - hard to see from the photos if there's an infection - but if it gets fluffy or looks worse, post more pics and more action would be needed. But for now, increased water changes would help, the clean fresh water and cleaning the substrate reduces harmful organisms in the tank that could cause an infection, and boosts the fishes immune systems so they stand the best chance of healing and fighting off any secondary infections.
So which substrate do they have? And is there any decor they could be scraping against when hiding?
I forgot to say, corydoras need more insects and protein in their diet than algae/veggies. While they relish the odd algae wafer, that should be an occasional thing, and not the staple part of their diet. For everyday food, Bug Bites is an excellent food for them, made of insects and a good quality brand. bloodworms are fine once a week or so, but if you're able to get frozen foods that's great, but try for a variety - mosquito larvae, daphnia, cyclops, brine or mysis shrimp - all good insect based foods that will be much better for them than peas and algae wafers.
Thank you for all of this info. Really helpful.They're often more active in the evenings, like to swim about in a big group? That chunky female in the first pic looks as though she might be full of eggs, so the activity you're seeing might be pre-spawning behaviour. If you see the smaller, slimmer cories following the larger, chunkier ones around, that's normal pre-spawning behaviour.
Glad you're upgrading the tank to a good sized one, you've seen that the current one is a bit too small for this amount of fish, and for C. aeneus, the cories you have, they can get pretty big before you know it!
What substrate do you have them on? For now, I'd recommend increasing the volume of the water changes. Change 40-50% every other day. If there are missing scales, that does leave them at risk of a secondary infection - hard to see from the photos if there's an infection - but if it gets fluffy or looks worse, post more pics and more action would be needed. But for now, increased water changes would help, the clean fresh water and cleaning the substrate reduces harmful organisms in the tank that could cause an infection, and boosts the fishes immune systems so they stand the best chance of healing and fighting off any secondary infections.
So which substrate do they have? And is there any decor they could be scraping against when hiding?
The substrate is sand. In honesty, the cleanliness of the sand is the point part of tank maintenance I'm struggling with. I don't feel like I'm syphoning it correctly despite watching some youtube tutorials.
I don't think they are grazing themselves though perhaps the castle ornament I have in isn't smooth enough. I might replace it with something smoother for the new tank just in case.
No problem! That's what we're here for
I'm only a few years into the hobby myself, so I really like helping people who are new to the hobby but keen and want the best for their fish! Because I remember how tricky it was learning to clean the tank properly, wondering whether it's clean enough, or if I'm overcleaning it (which is a real thing that can happen!) etc. There's a really steep learning curve to the hobby especially in the first year or so, but you'll get there! Sand is good for cories for sure. Is it a fine sand though? Brand?
People probably get sick of my linking these same videos all the time, but I found them soooo helpful, so I always urge people worrying about syphoning or cleaning the substrate to watch them.
He shows how to clean gravel at first, but does cover how to clean sand later in the vid.I also find this article from our very own @AbbeysDad to be delightful and helpful!
If you still have any question or concerns, don't be afraid to ask!
Could be, sometimes there's some rough edges from the manufacturing. Take it out and feel around the entrances and holes. You can sand down any rough edges you find!
No problem! That's what we're here for
Sand is good for cories for sure. Is it a fine sand though? Brand?
People probably get sick of my linking these same videos all the time, but I found them soooo helpful, so I always urge people worrying about syphoning or cleaning the substrate to watch them.
I also find this article from our very own @AbbeysDad to be delightful and helpful!
If you still have any question or concerns, don't be afraid to ask!
Could be, sometimes there's some rough edges from the manufacturing. Take it out and feel around the entrances and holes. You can sand down any rough edges you find!
Thank you so much!
So this is the sand I've got..
Attachments
Hmmm, I don't know that one, and can't find it via google - where did you buy it from? Does the sand look and feel smooth? Rough edged sands are abrasive, and can be a risk to corydoras delicate barbels on their faces. They also filter feed when given the chance, taking the sand and food into their mouths, sifting the food particles out and expelling the sand through their gills. So a rough sand isn't great for them.
You are so helpful thank you. It's from my LFS. I'll look into this now too.
Since you're upgrading tanks anyway, it's a good time to make sure the substrate is right.
It doesn't have to be an expensive sand either - the basic Argos play sand is aquarium safe, and super cheap! Much more affordable than store bought aquarium sand. I'm thinking of using it in my own tank upgrade. It's soft and fine, so great for cories, and can still grow beautiful plants in it. Check out @mbsqw1d 's tanks, he uses it, and has stunning plant growth! Plus happy, breeding cories
Great I'll look at that one thanks. I've been reading up on sands. My sand is black and I didn't even think to mention it as I didn't even know that colour was relevant but now I'm wondering if the sand is sharp as it is particularly around the cories faces that their scales are missingSince you're upgrading tanks anyway, it's a good time to make sure the substrate is right.
It doesn't have to be an expensive sand either - the basic Argos play sand is aquarium safe, and super cheap! Much more affordable than store bought aquarium sand. I'm thinking of using it in my own tank upgrade. It's soft and fine, so great for cories, and can still grow beautiful plants in it. Check out @mbsqw1d 's tanks, he uses it, and has stunning plant growth! Plus happy, breeding cories
Definitely worth checking it out!
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