Cories scared of me all the sudden?

[glassescat]

I few months back, I started with six peppered cories. One died shortly after bringing them home due to some swim bladder issues I was too late to resolve. And then, out of nowhere, I lost another cory a couple weeks ago due to unknown reasons (though it was much smaller than the others so it might be related).

I recently added in a dual sponge filter to my tank since I plan to switch over to a 20 gallon long and my current filter is built in the back and cannot be moved. So I'm letting the sponge filter run until I'm ready to begin the transfer this coming spring. But, ever since the addition of the filter and the loss of the one cory, my cories have gone from being excited little puppies whenever they see me to being scared of me and swimming away, and just being overall skittish.

I checked the water parameters and everything is normal, so that's not the cause. I'm guessing either my remaining cories are stressed out by the sponge filter, or they feel less safe with one less cory around and I'll have to stop at the LFS to get another one.

 

[otterblue]

they feel less safe with one less cory around

I'm no fish therapist, but I think it probably is that. Two or 3 more might be good.

 

[Marlene327]

I have a tank with 3 and another with 4 and they've been fine. Peppered are usually pretty good in 3's, had them in another tank and they bred all the time, happy little campers!

It's hard to tell what happened to make them skittish. Maybe just having more bubbles/agitation in the tank set them off. If you have some hiding places so they don't feel vulnerable it could help them. One of my tanks has upwards of 30 cories now and there's some I rarely see, they hide in the plants.

 

[glassescat]

I have a tank with 3 and another with 4 and they've been fine. Peppered are usually pretty good in 3's, had them in another tank and they bred all the time, happy little campers!

It's hard to tell what happened to make them skittish. Maybe just having more bubbles/agitation in the tank set them off. If you have some hiding places so they don't feel vulnerable it could help them. One of my tanks has upwards of 30 cories now and there's some I rarely see, they hide in the plants.

I'm kind of wondering if they are just a little spooked by the extra bubbles/agitation. Today they were a bit less skittish, saw one snuffling along the sponge filter looking for bits of food, and they're now snuggled in the corner by the java fern. Hopefully they'll start to calm down a bit more as they get used to the sponge filter.

 

[Spudsssy]

20gal long and larger school of cories will help. I find having a school of mid/top level fish make bottom dwellers more comfortable.

If smaller fish are happy out swimming above them, then they have nothing to worry about .

 

[Zonotrichia]

20gal long and larger school of cories will help. I find having a school of mid/top level fish make bottom dwellers more comfortable.

If smaller fish are happy out swimming above them, then they have nothing to worry about .

It might be too soon to tell, but I've already noticed a difference in my skittish school of Corydoras sterbai after adding a school of harlequin rasboras to the mix. I would also recommend increasing number of corys, as others have said. But it also sounds like sometimes...they're just shy.

(And re: the sponge filter being the culprit, that may be the case, but my sterbais love their sponge filter and spend much of the day huddled behind it and/or playing in the bubbles if they're feeling braver.)

 

[Chiz]

20gal long and larger school of cories will help. I find having a school of mid/top level fish make bottom dwellers more comfortable.

If smaller fish are happy out swimming above them, then they have nothing to worry about .

I have green emeralds in a planted tank that has also has white cloud minnows (and cherry reds), and the corys are always out and about and very 'playful. I added a small school (5) of sterbai to a heavily planted 29 gal a few months ago that has no other fish (and blue dreams), yet they still dart for cover when they see or sense danger. I attributed it to the sterbai just being nervous, but the minnows swimming above makes sense.