Corydoras Trouble

[IronChefItaly]

Alright so I’m looking at stocking some corydoras again but I’m a but reluctant because my first experience wasn’t all too great. My community tank is fairly established and chemically stable but for some reason my cories never did well. My set up is a 26 gal bow, heavily planted, fluorite substrate, shrimp and cardinal tetras. Coincidently all my sterbai corys came from the same LFS and they were never in the greatest shape when I picked them up - missing barbels, fungus / rotting fins. Anyways, they would generally last anywhere between 2 weeks to maybe 3 or 4 months before dying off one by one. Generally I would observe rapid breathing, inactivity, loss of appetite then death with 0% recovery from first sign of symptoms.

Couple things I’ve considered as a cause.

· Poor health of stock from pet store

· Dirty substrate – tough to get to a lot of areas of my tank with the gravel cleaner

Most likely a combination of the two, the overall water chemistry of my tank is always great but I could see ammonia collecting in the substrate where the cories spend most of their time. Has anyone else had similar experiences or suggestions? I’d like to be certain of what my problem was first time around so I can correct it.

Thanks for reading!

[JORG]

If your Cardinals are doing fine I can't think of any reason other than temperature or diet that would cause the corys a problem. I suspect you started with crappy stock. Perhaps try to get some corys from one of the board members here.

[jvision]

To add to what Jorg said, the only other cory-specific problem I could see is that maybe there isn't enough water movement from top to bottom of the tank. I've seen it where top and mid-level fish do fine, but bottom dwellers suffer b/c there isn't enough O2 getting to the bottom of the tank.

[IronChefItaly]

If your Cardinals are doing fine I can't think of any reason other than temperature or diet that would cause the corys a problem. I suspect you started with crappy stock. Perhaps try to get some corys from one of the board members here.

To add to what Jorg said, the only other cory-specific problem I could see is that maybe there isn't enough water movement from top to bottom of the tank. I've seen it where top and mid-level fish do fine, but bottom dwellers suffer b/c there isn't enough O2 getting to the bottom of the tank.

Thank you for both of your responses! Some very good points made but after some research I think i can rule out most of them.

I've always kept the temp a little cool ~26 degrees but i think that's still well within their range. As for O2, i thought you were right on the mark when you brought that to my attention as my tank does have strong flow (vertically mounted spray bar - eheim) but just because of my layouts and plant density there are still a couple dead spots here + CO2 injection. But i read up "All corys are facultative air breathers, meaning they have the ability to breathe atmospheric air to a certain extent if necessary. They possess a modified, highly vascularised intestine to aid in the uptake of atmospheric oxygen. This adaptation allows them to survive if their habitat becomes oxygen-deprived for any reason." - http://www.seriouslyfish.com, still not sure if that's enough though.

Which leaves me with diet and crappy stock. I don't know what the hell i was thinking but for the longest time i was feeding all my fish the aquafin flakes that came with my aquarium. At the time i was supplementing that with some bottom feeder pellets and rarely brine shrimp or blood worms (once a week maybe?). One important thing to note, is that i've also had problems in the past with over feeding... are cories particularly sensitive to it?

Anyways, the two of you have boosted my faith a bit so i'm going to increase the flow near the bottom and pick up my gravel maintenance / access then look for a local breeder on the forum. Cories are probably my favorite fish so I'll be quite happy if i can successfully stock them again.

[SuperShawn]

I keep many Cory's and breed some as well. Diet could be an issue but it sounds to me like you started with unhealthy stock. I never purchase fish if they show any signs of illness or poor physical shape.

As far as over feeding, I feed all my Cory's live or frozen food daily and quite heavy when I'm condoning them to spawn, the only thing I suggest is to keep water conditions clean as excess food will spoil quickly.

[redcherrybarb]

I think you were just doomed from the start. I wouldn't be scared of corys. If you get relatively healthy fish from the start they will thrive in a clean, well maintained tank!

I have 5 strebai corys in my planted tank with my neons, snails and plants. I feed the tank flakes, sinking wafers, gel food (homemade or Repashy) and frozen mysis shrimp, changing things up everyday. I never have been overly fussy with the tank, I just don't over feed.

My corys are chubby, pushy little guys that will knock an assassin snail off a piece of freeze dried shrimp. I "rescued" them from my local LFS (which sucks) and they are doing fantastic. I find keeping them in small schools really helps them a lot to feel comfortable.

I say go for it again! But as suggested, start with good stock and you won't have those same issues. They are such sweet little guys!