Cory behaviour and colour change - Tropical Fish Keeping - Aquarium fish care and resources

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post #1 of 27 Old 02-21-2013, 05:12 AM Thread Starter
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Cory behaviour and colour change

Hi all,

One of my two Corys has started to act quite docile this evening and he looks like he's getting pale. He seems to be spending more time than usual at the bottom of the tank. He usually spends loads of time with his mate side by side.

I did read somewhere that this can be natural but I am looking for some advice. I feed the Corys the biscuit things but the other fish seem to be very greedy. I feed them tetra colour pellets which float and then hide the buiscuits to try and give the Corys a chance to find them but to this day I'm not sure how much food the Corys are getting... The tetras, angels and mollies are speedy eaters.

I feed them every other day.

My fish are in a 153 litre tank with the following friends:-

1 x Koi Angel
1 x Marbel Angel (small)
4 x Tetras (small to medium)
2 x Balloon Molly's (small)

I tested the water earlier for pH, Ammonia, Nitrate and Nitrite.
pH was 7.6
Ammonia was trace but less than 0.25 ppm
Nitrite 0
Nitrate trace but less than 5

I performed a 20% water change on the weekend and the tank has a couple of bits of driftwood and, some plants and some rocks.

Lastly I have an Eheim canister filter pumping 1000 LPH.

The tank has been set up since October last and along the way I have sadly lost 2 of my tetras. To this day I have no idea why but my water levels have always been trace.

Can anyone give me some advice on why my cory is being docile?

Thank you all

Thanks very much,

Rich Bennett

153 L / 40 US Gal Tank with:-
- 11 x Widow Tetras
- 2 x Clown Loachers
- 2 x Bottom Feeders
- 1 x Koi Angel

15 L / 4 US Gal Tank with:-
- 1 x Very Small Beta
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post #2 of 27 Old 02-21-2013, 05:31 AM Thread Starter
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Here is a picture of him
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File Type: jpg image.jpg (69.9 KB, 65 views)

Thanks very much,

Rich Bennett

153 L / 40 US Gal Tank with:-
- 11 x Widow Tetras
- 2 x Clown Loachers
- 2 x Bottom Feeders
- 1 x Koi Angel

15 L / 4 US Gal Tank with:-
- 1 x Very Small Beta
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post #3 of 27 Old 02-21-2013, 07:18 AM
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I am curious what kind of tetras you have. At first glace I am wondering if it is related to pH. Cories like more acidic water. I am also curious if you are adding any aquarium salt, this is not advisable with cories. Adding bog wood is an idea for lowering pH. Plus it is where cories are most comfortable.

I personally do not have experience with Angels but they also like acidic water on the fish profile.

Are there other signs of illness, like ich?

I would also do another partial water change to remove more ammonia. Ammonia is dangerous stuff.

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post #4 of 27 Old 02-21-2013, 09:34 AM
I'm thinking you might use a sinking pellet food for bottom feeders....and maybe even feed after the lights go out when Corys tend to feed and competition is low.

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post #5 of 27 Old 02-21-2013, 11:01 AM
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NM.........re read OP
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post #6 of 27 Old 02-21-2013, 11:20 AM
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I concur with what has been posted on putting some sinking foods in after darkness, since corys are nocturnal.

Ammonia should be zero in a tank running since October [4+ months], and particularly with live plants. Have you tested the tap water for ammonia (and nitrate while you are at it, just so you will know)?

Corys are shoaling fish and need a group, no less than five. I'm not saying this is the cause, but the more there are, the more settled they will be.

What is the temperature of the water?

One must also accept that fish do die now and then. We cannot know what injury may have occurred to a fish at some point in the past, and then there is the matter of the long-term effect of water issues. I can't see anything in the photo, but such injuries/issues would be internal and unseen.

Byron.

Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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post #7 of 27 Old 02-21-2013, 11:53 AM
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Cories, need to be in a group of at least five I feel.. you can also get away with keeping like 3 of each from two different species, but the fish nay be stressed from a lack of having a shoal to swim with.

+ Planted 75 Gallon Amazonian Tank +

Cardinal Tetras -- Rosy Tetras
Ember Tetras -- Silver Hatchetfish
Diptail Pencilfish -- Cories
Bristlenose Pleco
Lyretail Checkerboard Cichlids
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post #8 of 27 Old 02-21-2013, 12:34 PM Thread Starter
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Hi all,

The food I feed is sinking food. It's sera vipachip.

The tank is currently at 27 degrees C

It has spiked recently with the warm temp in Australia and hit 28 degrees C yesterday.

I have also recently added a little aquarium salt. 1 level teaspoon per 10 litres is what I followed.....

I took him out of the tank last night and put him in a hospital tank with some promethyasul and he appears unchanged overnight - very still and signs of laboured breathing.

The conditions of my tank appear to be so good in general and all the rest of the fish are excellent!?

I am happy to get a few more Corys but will my tank be a little overstocked?

Thanks very much,

Rich Bennett

153 L / 40 US Gal Tank with:-
- 11 x Widow Tetras
- 2 x Clown Loachers
- 2 x Bottom Feeders
- 1 x Koi Angel

15 L / 4 US Gal Tank with:-
- 1 x Very Small Beta
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post #9 of 27 Old 02-21-2013, 02:34 PM
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Quote:
Originally Posted by beano129 View Post
Hi all,

The food I feed is sinking food. It's sera vipachip.

The tank is currently at 27 degrees C

It has spiked recently with the warm temp in Australia and hit 28 degrees C yesterday.

I have also recently added a little aquarium salt. 1 level teaspoon per 10 litres is what I followed.....

I took him out of the tank last night and put him in a hospital tank with some promethyasul and he appears unchanged overnight - very still and signs of laboured breathing.

The conditions of my tank appear to be so good in general and all the rest of the fish are excellent!?

I am happy to get a few more Corys but will my tank be a little overstocked?
This is beginning to give us more probables, mainly the salt. A teaspoon per 10 liters equates to a teaspoon per 2.5 gallons, and that is a lot of salt. Why were you adding this? Corys are not going to last long if this continues. I would do major water changes to remove most of the salt. You can read more on the harmful effects of salt on freshwater fish here:
http://www.tropicalfishkeeping.com/f...quarium-97842/

Second, the promethyasul. I am not familiar with this, so I tried to find out about it online. From the little I can find, it contains malachite green which corys do not like at all. This seems to target external issues, which I doubt very much applies to the cory. Unless one can very accurately diagnose a problem, medications should not be used. They add to the stress of the fish which further weakens it, and this means the fish is wasting energy that could better be used to fight the actual problem. The laboured breathing is a common result of any medications. As some one here or in another thread mentioned, one of the best remedies is a water change. This certainly cannot hurt a fish, and it may allow the fish to gain some strength.

Temperature may be OK, from the photo this looks like a Corydoras sterbai and they can manage with warmer temperatures. Most corys are best below 24-25C/75-77F. But temporary rises during summer is not usually an issue, as it cools down at night and this is far different for the fish than a constantly warm tank.

On the stocking, this is a case where the fish has to be in adequate numbers to be at its best to begin with. Five corys is minimum. They are not heavy on the bioload. Live plants help too. And regular (weekly) water changes of half the tank volume.

I would do a 75% water change now to dissipate the salt and medication. It may or may not save the cory, but it can't make things worse.

Hope this is of some help.

Byron.
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Byron Hosking, BMus, MA
Vancouver, BC, Canada

The aquarist is one who must learn the ways of the biologist, the chemist, and the veterinarian. [unknown source]

Something we all need to remember: The fish you've acquired was quite happy not being owned by you, minding its own business. If you’re going to take it under your wing then you’re responsible for it. Every aspect of its life is under your control, from water quality and temperature to swimming space. [Nathan Hill in PFK]
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post #10 of 27 Old 02-21-2013, 02:38 PM
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I cant see the pic at work but the problem is likely the high temp and salt combination. I have not added salt to a tank in 25 years and IMO is not needed. Cats are sensative to salt and would suggest large water changes and to stop adding salt.

Cory typically like an average temp 74F/23C , 78F/27C would be on the upper end on the recommened temps for most species.
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