Why do my corys change colour every night???

I have 3 bronze corys, 1 female and 2 males. I am completely puzzled by this, every night when i go to bed i feed them, and every single nght when my corys come out for food, the have no black stripe on them, they are just bare, and in the morning, their black stripe down the middle of them is back!!! I have asked my sister, and she said its just the way they feel, but its all of them!!! I would undrstand it if it was just one, but all of them?? plz help!!!

Usually, a fish's color will fade when they are under stress. That may not be the case with your aquarium, but checking the water parameters would be a good idea. Also make sure you are not over feeding.

i defo know i dont over feed, my sister has a tank the same size with around the same amount of fish and she feeds twice a day, whereas i only feed once a day. I have had these corys for a few months only, the nitrate is perfect and ph is too, so i dont know what the problem is?? x

Did you also check for ammonia? Although I have three cory cats in one of my aquariums, I'm no expert on the species. None of mine have ever changed colors that I know of. I'm pretty sure you can get more detailed information by entering their Latin name in Google. At least it worked for me on killie fish.

well, its not that they are ill or anyhting, theyre eating and swimming and acting normal, i was just curious thats all.

my corys do that too. I read into it and it may be because they are mating. but my corys are peppered corys, i have one bronze cory, only because it was labeled wrong at the pet store. broze corys are shiny and green, they also grow way bigger than normal corys, which makes me wonder if the are really the corydoras species.

so are my corys bronze or not then?

A bronze or what some call green cory does have a dark strip down the side by the dorsal fin.
There are so many different varieties...some are hard to tell apart.
The fact that your cories are changing color though indicates they are under stress.
Please get yourself a test kit & check water parameters.
Reason these cories are going from normal coloration to faded is probably due to water quality as JohnA mentioned.
Have you checked "ammonia" level?
There should be none.
What other fish do you have in this tank ?
What size tank?
..and how often are you doing water change
( removing old & adding new condtioned)?
Cories may not show signs of illness until it is too late.

Ammonia, nitrate and ph are all perfect. I have in this tank 2 mollies, 1 silver and 1 black, 2 red eyed sword tails, small bristle nose, 3 corys and a gibby plec. The only thing i can think of is the water. The water is like a murky brown clolur. I have done numourous water changes at different times to try and get it clear, but its impossible without shocking the fish by doing such a high water change percentage. Maybe its that?? I dont know. . .

How large is the aquarium, and how much light is it getting? The brown stuff could be algae.

I just looked in our blog section, and one of the older ones had a link that talks about cloudy water. It says the brown or yellow tint can be removed by adding activated charcoal to the filter. You may have too many nutrients in the water, and that's caused by over crowding or over feeding. Live plants can help.

The tank is only 5/6 gallon. It gets quite a bit of light. My sister says its the sun, so i have started shutting the curtains, but it makes no difference!! I wouldnt say its over crowded. I have had more fish in there at a time, and they were all fine. I dont think its algae as i have 2 plecs in there, one about 4/5in, and he doesnt miss much!!! Also another thing, there is quite alot of waste at the bottom. I have tried to get it out with a syphon, but I always miss some!!!!

Getting out all the cory or pleco waste is always such a chore.

I don't know... I may personally go back to gravel in my tanks. Except my little bitty angel fry tank.

I just like the undergravel filter and the idea of being able to plant the plants in the gravel instead of in pots.

I'm fed up with trying to more the pots and get all the waste... it's more like a chore than a hobby!!!

Although, I know that cory cats like sandy bottoms... I haven't experimented with this yet. Although I'm fixing to. I have another tank and I'm splitting my greens and albinos to see if I can pull off a breeding...

Wish me luck!

I've had corys in a small community tank with an under gravel filter. Although I didn't notice at the time, they spawned, and a few survived. If I were to try for another spawn, the cories would get a single species tank with UGF and bunches of live plants. Have you ever tried to get albino cories to spawn?

Nope, not albinos. I have with bronze corys but they didnt seem to want to. I didnt trigger them though as i was inexperienced then lol!! Does anyone have any more ideas of what could be triggering my corys to change colour? Its getting so bad now that im having trouble seeing the fish please help!!!

In my experience, it's much more difficult to keep a small aquarium clean than it is a large one. If you have even slightly too many fish or too much food in a five gallon tank, it will get out of control very quickly. Sometimes you can get by with a too large biological load, but even a small thing will upset the balance. Put the same biological load in a large aquarium and it takes more mistakes to upset the balance. Plecos can be very large and very messy, and I'm not at all sure they are ideal for a small aquarium. Bigger aquariums are not expensive if you buy them used, and a 20 or 30 gallon tank could solve your problems. The 5 gallon tank is good for spawning gouramis or bettas as well as some small species.

I didn't realize how small your tank was. Upon re-reading your posts... You have too many fish in not enough water.

You probably are getting too much waste/excess food in the water and that's why it's brown.

I have to recommend getting a larger tank. I feel that one you can't see the fish, you're going to end up finding them dead.

If you need to buy some time... to get a bigger tank, you need to be doing 50% water changes every day or every other day.

This will help with the cloudiness... This is not ideal conditions for the fish.

I've had this situation happen in an overstocked 10 that I was just trying to get by with until I got another bigger tank, and it just didn't work.

My 2 cents: Get a bigger tank.

Good Luck to you!

OK thanks alot for your suggestions. I have take it on board and am saving up!!

I always recommend yard sales for cheap aquariums. In Phoenix at least, used aquariums are very inexpensive.

Definately! Depending on where you're at... I'm in Tennessee... and I try my best not to pay more than a dollar a gallon. And I won't pay more than that for the glass.

Depending on what comes with it, I'll see if it justifies the price.

But remember... See if you really need all the stuff it comes with. Sometimes more stuff isn't the greatest... Sometimes more stuff is just more stuff...

Good Luck!