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tanker 03-14-2010 11:47 PM

Corydoras julii questions - new setup, considering cories
I am considering what fish I can get when I've cycled my tanks and I like the look of the corydoras julii so I'd like some opinions about its suitability for my setup.

I have a 35-litre tank and am getting a 75-litre tank as well. I have 5 platies at the moment (at least I hope I still do, one seems to have disappeared...). At this stage, I can be flexible about how to arrange them and I can split them up between the tanks if necessary. I've been advised that 5 is too many for the smaller tank, so I'm either going to move all of them (hopefully I'll still have them after the tank has cycled) to the bigger tank, or move some of them at least.

Compatibility with platies
So, the first question is, are the julii compatible with platies?

Tank size
From what I've read so far, they'd only be suited to the bigger tank, but is it big enough for them?

Number of fish
I've read that they want a school, but I've read opinions ranging from 2-6 as being acceptable numbers. I'm thinking that 5 sounds like a good number, but when considering that many, the question is whether there's enough room for 5 platies and 5 catfish in the bigger tank?

Water alkalinity
The water here is naturally alkaline. It tested at 7.8 (or higher, that's the highest on the chart). The aquarium shop sold me some pH neutralizer but I've been advised in my other thread that I should leave the pH alone. Can the julii cope with my water pH?

Other options
I'm open to other suggestions for small bottom feeders suited to what I have. Unfortunately, the pygmy cories don't seem to be available locally (I haven't checked all shops, but the ones I usually go to don't have them). They do have the julii which seems to be one of the smaller ones available to me and I like the look of them.

I'd appreciate any opinions or advice. Thanks.

JMILLER 03-15-2010 11:28 AM

I'm not sure on the compatibility issue but I may be able to answer the rest.

tank size... I currently have 3 in a 10 gallon (37L ) and that is about the maximum you would want for that size tank. From what I read the larger the tank the more active they are

number of fish...I originally had just one for a few months until I found out they were schooling fish, while alone all he did was stay in one spot in the tank, since adding the other two all are quite active now but 5+ would be better

water...mine is 7.8/7.9 and they are fine

Cories have quickly become one of my favorite fish, The three I have a quite the odd trio. The one I've had the longest is a lot larger than the other two and the most timid, the middle one is just kind of average but the smaller one (just a baby) is something to watch. It constantly plays in the filter current either swimming against it then suddenly heading off to one side and using it's momentum to shoot it across the tank or swimming to the surface and riding the current down the front glass then off to the side. They are quite entertaining.

Bacchus 03-15-2010 12:27 PM

i have a school of six, and similar water parameters and they are all fine. one thing though, true julii corys are actually a rare find. most of the time, the stores are actually selling you Corydoras trilineatus, or 3-lined corys.

when keeping corys you should ideally be using sand for substrate, or at the least small substrate with no sharp little edges. otherwise, their barbels get damaged and impede them from finding food

Byron 03-15-2010 02:17 PM

Your 75l (=20 USg) tank is fine for a group of 5-9 Corydoras. You could have 3-4 in the smaller tank. With corys the issue is not so much space (area of the substrate) because they are not active swimmers like the platies and many tetras. They spend their day browsing over every surface in the aquarium, substrate, plant leaves, wood, rock... so the more of all this the better/happier the Corydoras will be. Provided water quality is good (regular maintenance, and live plants help a lot) 3-4 corys with a small shoaling fish group or a pair of something would be fine in the smaller tank.

Most of the common Corydoras species are fine with livebearers. Some of the more rare or sensitive species do not fare well in basic/alkaline water, but the common spotted species like C. julii, C. trinlineatus, etc., and C. aeneus or C. paleatus are OK below pH 8. The last two species in particular have a wide tolerance in water chemistry, more than any other Corydoras species. And yes, do not fiddle with water parameters; know what you have and work within it, there are a lot of fairly adaptable fish species out there.

Pygmy corys are one of the sensitive species. Many members here have posted about losing most or all of their pygmy corys. In my 20 years with these fish I have had good luck with them, but only in established tanks (after at least 3 months but preferably 5+ months) and in soft, acidic water. They also do not like higher temperatures (up to the normal community temp of 78F/25.5C is fine).

Five of each of the corys and platys in the larger tank is OK. You could have two Corydoras species, say 3 of each, if you want more variety. Most of them will chum around with other species, though some do have a preference for their own species and I have found 3 of a species satisfies this mwhen I have several different species.


LisaC144 03-15-2010 02:22 PM

The only thing I would add here is that is it usually recommended not to add cories until the tank has been established for a couple months. They can be fairly sensitive (some species more than others as Byron stated) and appreciate a well established tank.

tanker 03-15-2010 11:55 PM

Thanks for all of the replies. I am going to get some when the tanks are well established.

My substrate is gravel - it's not very fine, but it's smooth. Hopefully it'll be ok for them.

If the pygmy cories are sensitive and like soft acidic water, that probably explains why they aren't available locally where the water is hard and alkaline.

Yes, I'd read about the confusion between julii and trilineatus. The shop says they are julii. I'm not that bothered if they are the other ones, they look nice whatever they are.

(BTW, I lost the platy who went missing.:-()

Byron 03-16-2010 11:40 AM

Regular aquarium-type gravel is fine for Corydoras, I've used it for 20 years with no issues. It's the sharp edges that are a problem, not only for their barbels but undersides and this applies to all bottom-dwelling fish. Run a handful of gravel through your fingers and chances are it will not feel rough or sharp, and that is OK. Sand is more necessary with burrowing fish like some loaches, rays, etc. B.

Bacchus 03-16-2010 05:08 PM

regular gravel with rounded edges will work fine, but corys will be their happiest with a fine sand substrate. they enjoy rooting around in the sand with their faces looking for food, and love to sift it through their gills at times as well. you would never see that with gravel

here is a video i found of them rooting around in sand:

tanker 03-16-2010 10:30 PM

Would it be possible to put a little container of sand in there? Would they use it or would they just throw all of the sand out and make a big mess? If so, what sort of plastic is aquarium safe?

Bacchus 03-17-2010 12:08 AM

i wouldnt bother with a small container of sand....just either go all sand or all gravel. they will do fine if gravel is what you have, as long as there are no sharp edges to it.

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