Pygmy Corydoras size disparity

Adavachi

A couple of my pygmy corys are smaller than the other 4 is this because of sexual dimorphism or are they not getting enough to eat? I'm worried that the other bigger fish are hogging all of the food.

tank is a 29 gallon and has:
6 cherry barbs
6 pygmy corydora
1 feeder goldfish (I know he'll get too big, but I'll rehome him later)
 

Zach72202

Pygmy cory's are naturally, well-pygmy. How long have you had them?

Something to note with them is that they don't need much more than a morsel of food to eat. Quite honestly even if a few flakes are hitting the bottom its probably enough for them as such a small fish a tiny stomach. Not saying they don't need to be fed, but if you see food hitting the bottom in any amount, they are probably eating.

Another thing is that corydoras, pygmys especially, are slow growing. With pygmy's they are so small at full size even that a 'juvenile' at 2 months old is like the size of a 1 week old guppy. There is dimorphism, but it is subtle as the females will be more 'rotund' in the abdomen area where the males are kinda skinny looking. It can be hard to notice in a moving school, but once you really look at them side by when they are still you can sex them. It doesn't really have anything to do with the length.
 
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DoubleDutch

Uhhhhh males are smaller than females.
 
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Adavachi

Pygmy cory's are naturally, well-pygmy. How long have you had them?

Something to note with them is that they don't need much more than a morsel of food to eat. Quite honestly even if a few flakes are hitting the bottom its probably enough for them as such a small fish a tiny stomach. Not saying they don't need to be fed, but if you see food hitting the bottom in any amount, they are probably eating.

Another thing is that corydoras, pygmys especially, are slow growing. With pygmy's they are so small at full size even that a 'juvenile' at 2 months old is like the size of a 1 week old guppy. There is dimorphism, but it is subtle as the females will be more 'rotund' in the abdomen area where the males are kinda skinny looking. It can be hard to notice in a moving school, but once you really look at them side by when they are still you can sex them. It doesn't really have anything to do with the length.
I have hikari sinking wafers and I usually drop 1 in there everyday. The leftovers tend to get eaten by the other fish in the tank so food isn't getting wasted. I also try to put my flakes into the tank so that they will sink. I have only had them for 2 weeks, but they were REALLY small when I first got them and I've noticed that a few of them have grown a bit since I got them, but also the smaller ones were originally smaller than the rest to begin with. Just wondering if it's normal for there to be size disparity.
 
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Zach72202

Uhhhhh males are smaller than females.
I would say they are yes in girth, but by terms of length, maybe 1/16th or 1/8th inch smaller- not really enough in my opinion to say they are dwarfed compared to females. I have Corydoras pygmaeus, and sexual dimorphism of them isn't extremely noticeable at a glance, unless you are very familiar with corydoras, but yes, I do agree with your statement.


Just wondering if it's normal for there to be size disparity.

Yeah the biggest thing to watch is if they are getting skinny or just don't look right compared to the others. I would say by the sounds of it they are doing good, but the cory's could be:
1) Wild caught so all different ages
2) Tank raised from the same batch, but some fish grow faster than others, known as 'racers'- which this completely normal
3) Tank raised and from different batches so different ages.

If you are real worried about it, I would say feed right before the tank lights go out and wait for the corys to come out and watch from a distance if they are eating. It might take a while if they are shy, but you should see them eating.
 
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Flyfisha

It is possible to starve Pygmy corydoras but you are not going to do it in two weeks. Any size difference is from the previous tanks feeding routine. No creatures grow well if they have to compete for food with more dominant species and more dominant members of their own kind.
I put my hand up and acknowledge that I probably starved a group of pygmy corydoras when housed with tiny ember tetras , endler/guppies, and cherry shrimp. At the time I did not realise how aggressive 100 adult cherry shrimp can be around food when they have the numbers to push tiny fish off food.At the time I was believing the pinch of food stories perpetuated on the internet.

All species of fish can go a week to ten days without food. However they do need to eat once in a while.

I have cherry barbs and consider them peaceful but fast eating fish. Watch closely to make shore some food is getting to EVERY pygmy ?
Both the goldfish and the cherry barbs at species that will pick up food from the gravel.

Just saying in your efforts not to have food sitting on the substrate rotting don’t go to far the other way and starve the little guys.

Feeding any corydoras is an issue with other tank mates. Like many other people I drop pellets in at night after the lights are out. But can still see with enough light who is eating.

You have not had them long enough to take any blame.
 
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Adavachi

It is possible to starve Pygmy corydoras but you are not going to do it in two weeks. Any size difference is from the previous tanks feeding routine. No creatures grow well if they have to compete for food with more dominant species and more dominant members of their own kind.
I put my hand up and acknowledge that I probably starved a group of pygmy corydoras when housed with tiny ember tetras , endler/guppies, and cherry shrimp. At the time I did not realise how aggressive 100 adult cherry shrimp can be around food when they have the numbers to push tiny fish off food.At the time I was believing the pinch of food stories perpetuated on the internet.

All species of fish can go a week to ten days without food. However they do need to eat once in a while.

I have cherry barbs and consider them peaceful but fast eating fish. Watch closely to make shore some food is getting to EVERY pygmy ?
Both the goldfish and the cherry barbs at species that will pick up food from the gravel.

Just saying in your efforts not to have food sitting on the substrate rotting don’t go to far the other way and starve the little guys.

Feeding any corydoras is an issue with other tank mates. Like many other people I drop pellets in at night after the lights are out. But can still see with enough light who is eating.

You have not had them long enough to take any blame.
I'm still trying to get the feeding routine settled in because I've only had the tank for about a month and I just got everyone into the tank from quarantine last week. I didn't feed for a couple days to allow the BB to catch up and then when I ended up feeding I fed WAY too much because I didn't want the corys to starve. I've only been feeding once per day, but I'm thinking about feeding twice per day and just putting a smaller amount of food in the tank. Thanks for the tips on not worrying about rotting food at the bottom of the tank, I feel like there won't ever be food rotting at the bottom of the tank since all of my fish tend to clean up after themselves xD. I have watched a few times too to make sure every single cory is at least getting some food and if I see one not getting food I'll feed more a little later in the day.
 
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