Pygmy Cories lethargic since introduced Endlers
I have a relatively new aquarium (35l, planted aquarium, 2 1/2 months old, 20% water change once a week).
In mid February we introduced 5 pygmy cories (not sure of sex, think 3 females and 2 males), and they were fantastic. Swimming all over the tank, playing together, and vacuuming the tank bottom.
After three weeks (three weeks ago) they'd settled in nicely and everything had stabilised so we introduced six immature endlers livebearers (3 male, 3 female). At first they all got on fine, even playing together, but now the cories have gone really quiet and shy, so much so that they barely move anymore :-(
The endlers seem fine and are very lively. The cories all look OK, still got their barbels, one maybe has slightly faded coloration but that could be my imagination. They do still swim about and feed but spend 99% of the time sitting on the gravel at the back of the tank. This is worrying because they had been so happy and lively.
What are the possible options?
- are they intimidated by the endlers?
- are the endlers outcompeting the cories for food? (but they don't go after food when it's dropped right next to them in the tank)
- are they depressed - we have hidey holes and plants, but is that not enough? Do they need counselling?
JasonI is quite correct, and that is one possibility. Another is the Corydoras pygmaeus themselves.
This is one of the most delicate and sensitive of the Corydoras species, and in relatively new tanks frequently do not last beyond a few weeks; I have experienced this myself. I can offer some suggestions perhaps, but first, what are your water parameters: pH, hardness, temperature? These all have a bearing on Corydoras.
Greetings, I would not consider this anything to be concerned about. Any group of Corys will go through periods of less activity than what you may be used to seeing. Some days mine are flittering all over the tank, especially when in spawning mode -and at other times they might spend many days, barely moving at all.
Although they have a reputation for being a sensitive fish, I have never found that to be the case. My original spawning group is at least 5 years old and in that time I believe I have lost 2 fish. Additionally, the females have grown so large that they barely qualify as "pygmys." lol.
When people write me, concerned about periods of inactivity and huddling, I usually recommend that they first try adding a few more fish to the group, provide a bit more cover and lower the lighting, which most people greatly overdo on their tanks. This generally provides a greater sense of security and can oftentimes have a dramatic impact on the activity of the group.
I hope that this helps. Cheers. - Frank
Thanks for your advice. Finally got hold of some test strips and checked the water quality today. All OK except slightly high on the nitrates. I'm doing a couple of significant water changes, making sure all the browner moss is cleared out and see how they get on.
As I see it, you have 5 pygmy corys and 6 endler's livebearers in a 10-gallon aquarium. The thing is that, in my experience, pygmy corys prefer the midwater areas that endler's also tend to gravitate to. I think your corys have been outcompeted by the more active endler's for the ideal space. I'd bet that they'd all be just fine in a 20-gallon long.
Sorry I missed your (fuse1001) last post mentioning nitrates; today's new post brought this thread back up.
What is the nitrate number? "High" can mean different things to different aquarists. This can be a cause of concern for corydoras.
And speaking of corys, how are they doing now?
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