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I have added five Corydoras sterbai to a 38 gallon planted aquarium. My tank is relatively new, although the water has been stable for about a week and a half now. I added first two C. sterbai, then three more three days later. They have been schooling constantly for four days along the aquarium walls, I presume because they can see their reflections in the glass. They almost never stop, although I would presume they would need to eat or rest.

This doesn't look like normal schooling behavior to me, but rather like fish that are really worried (not utterly frantic, but definitely not relaxed either). I believe everything is as it should be other than the pH - it's around 8. Could this be the problem, and are they trying to leave? I want to take care of them so they don't get too stressed out and die.

Further information:

Water parameters: pH around 8, ammonia 0, nitrite about .1 ppm, nitrate about 25 ppm, general hardness 300 ppm, carbonate hardness 250 ppm. Temperature 79-80 degrees fahrenheit. I'm currently changing 20% of the water daily, and the new water is within 1-2 degrees of temperature of the water being replaced. We're on a well, so there isn't any chlorine or anything in the water to worry about. Last week a small amount of yeast solution got into the tank from a knocked over yeast CO2 system, but the water never became cloudy and the small amount of yeast near where it came out of the bubbler is now gone (I'd been siphoning it up daily). Although I was worried, the fish didn't seem to have been bothered by it.

Tank: 38 gallon R-375 Lifetech aquarium, 30 plus plants (Vallisneria, Echinodorus, Bacopa, Mayaca, Rotala, java moss, etc.), rootwood, and a porcelain flowerport to hide in and around, but with open space too. Flourite gravel substrate with laterite and a substrate heater for the plants. The tank is near my computer at home, and doesn't have much activity around it (we have no kids, and the dogs aren't allowed in the room).

Lighting: Two 55 watt 50/50 Actinic/10K compact fluorescent bulbs, usually have both on only in the afternoon, with only one on in the morning and in the evening.

Filtration: R-375 submersed aquarium pump, which sends water to a wet/dry filter (with filter floss and ceramic beads/stones) in the aquarium hood; the water returns to the tank from the other end of the hood; there is also a bypass flow with a venturi valve which I have opened on full for aeration - the water flow is pretty fast, but the fish don't seem to mind.

Tankmates: 5 Otocinclus sp., 8 Amano shrimp (Caridina japonica), 2 angelfish (about 3 inches overall, bodies the size of a quarter), a few pond snails

Feeding: live tubifex worms, some dry shrimp pellets and other pellets corys should like, occasional frozen cubes of various sorts (uneaten food removed)

Should I be getting worried yet? Four days of almost uninterrupted schooling (one day for the new ones) seems awfully long for getting used to a new place...

I look forward to your comments.

Thank you!

Kirsten

It is a normal behaviur for all corydoras in the begining...
they are "exploring"...
After few days they will eaither settle down or start to breed like mine doo today
regards
Vedran

stina wrote:It is a normal behaviur for all corydoras in the begining...
they are "exploring"...
After few days they will eaither settle down or start to breed like mine doo today
regards
Vedran

Thank you, Vedran, for sharing your experience. Although I used to have many aquariums, it's been a number of years since I've had any. It don't remember corys taking this long to settle down before, but if they're going to decide they feel like breeding, that's certainly all right with me! As far as I can tell, I have one fully grown male and one fully grown female, one of each gender which are almost full-size, and one which is almost full-size which might be another male. Breeding would be great, but simply settling down and not behaving like a fish screen-saver in hyper-drive would be a welcome start

I think I've finally managed to get a bit of food into these guys since I posted a few hours ago. In the past few days I've seen almost no foraging, so this evening I decided to turn the lights off early and put a light with a red bulb on in the room to see what the corys are doing after dark. An hour later four of the corys were STILL swimming back and forth along the glass (so much for the reflection idea - I don't think they could see anything), but one of them - I call him/her "the sensible one" - was foraging. I went and got more live tubifex worms from the refrigerator and added about a teaspoon, and this cory just whipped around and raced to catch as many of the worms as he could. Bingo - I verified that he was hungry, and that he at least was ready to consider eating. I added about a tablespoon more worms, and at least one other cory started eating the worms that had floated over to the vallisneria "forest". I hope the other corys decided to eat too, but I didn't observe them doing so. However it's an hour or so later now, and I can't see any worms left (but the Amano shrimp have been helping clean them up as well; it turns out they LOVE tubifex worms too!).

So, I'll wait to see what the corys are behaving like tomorrow. Although three of them are still "pacing" up and down the glass in the dark, at least now two of them have chilled out for the time being. Here's hoping the rest of them will too!

Congratulations on your breeding corys I hope to have the same luck in my tank sometime too.

Kirsten

As of last night, for the first time the corys were willing to stop schooling against the glass when I fed them tubifex worms during the day. Last night, using a red light, I finally also observed them actually resting - it took them seven days to get to this point!

The three younger corys are the most willing to forage, and they are actually leaving the two older corys to school against the glass while looking for food for themselves. This evening when I put in live tubifex worms, the corys all came to eat them right away, so they're getting more relaxed. They're still not as mellow as I want them to be, but I now have hope that they'll begin to behave as though they live in this tank and it's home.

Is it normal for corys to take this long to get used to a new place? I selected C. sterbai because I think they're beautiful fish, but they're really driving me nuts with the constant swimming against the glass. I've only had C. julii previously, and they would of course occasionally swim up and down the glass, but mostly they just moseyed about looking for food or would just hang out looking relaxed. If C. sterbai truly never sit still (and it's not just an adjustment thing), maybe they're not a good fit for me. What is the experience of those of you who do have this species?

Kirsten

this is totally normal.. don't worry about it

I have three pictures to share: one of the way these corys have been behaving all too often, and the other two of them nicely foraging for a change.



This a picture of my Corydoras sterbai schooling incessantly â?? up, down, back, forth, repeatâ?¦ The older ones were in a small tank at the pet store for many months. The tank next to them had more corys than theirs did, so they often schooled against the glass to try to get together with the other corys. I wonder if their little brains are having trouble breaking away from this stereotypical "pacing" behavior. They are getting better though, so I hope fellow Catfish Forum participants are right that they will chill out sometime.



Now this is what I like to see â?? them as a nice friendly bunch of corys, not in a hurry, just foraging about.



And more friendly foraging (at least if youâ??re not a tubifex worm! â?? thatâ??s what theyâ??re looking for).

Again, thanks for the encouragement, Vedran and Madattiver - you're right, they're getting better

Kirsten

Well, finally after eleven days the school of C. sterbai have mellowed. They still school against the glass often, but they come and eat when I feed them and they look more at home. I hope they continue to relax further, but they're finally getting to the point that I can enjoy them.

And if I'm lucky, perhaps someday I'll get them to breed Thanks for the encouragement to stick with these guys. They're now becoming the fish I'd hoped they would be.

Have a nice rest of the weekend,

Kirsten