Are cory catfish sensitive to water changes?

[Dave K.]

Over the past couple months, I've had problems with my cory catfish dying in
my 20 gallon community tank. I've had one peppered cory in there for
probably a half year now, and he always does fine. But a few months ago, I
bought another cory, he died about three weeks later. I replaced him with an
albino cory (from a different pet store), and he's lived for about 6 wks.
But today he was dead at the bottom of the tank... we didn't notice any
problems with him and he has no signs of disease.

Anyway, all our other fish have been doing fine for months. I did notice
that these 2 cories died about 5-6 days after I did a water change. Are they
more sensitive to water changes than most fish? I usually change about
30-33% of the water every 3 wks. I know it's better to do smaller water
changes more frequently, but isn't changing 1/3 of the water every 3 wks, as
I do, still pretty good?

Any advice would be appreciated.

[RedForeman ©®]

cory's aren't peculiar about water changes, but seasonal changes in your tap
water may introduce different water that they may or may not be able to
adapt to... i can't imagine cory's being sensitive after 6 weeks... in the
first few days maybe, but other than initial introduction to a tank, I've
never lost a cory yet...all my cories are over 2 years old...

Post by Dave K.
Over the past couple months, I've had problems with my cory catfish dying in
my 20 gallon community tank. I've had one peppered cory in there for
probably a half year now, and he always does fine. But a few months ago, I
bought another cory, he died about three weeks later. I replaced him with an
albino cory (from a different pet store), and he's lived for about 6 wks.
But today he was dead at the bottom of the tank... we didn't notice any
problems with him and he has no signs of disease.
Anyway, all our other fish have been doing fine for months. I did notice
that these 2 cories died about 5-6 days after I did a water change. Are they
more sensitive to water changes than most fish? I usually change about
30-33% of the water every 3 wks. I know it's better to do smaller water
changes more frequently, but isn't changing 1/3 of the water every 3 wks, as
I do, still pretty good?
Any advice would be appreciated.
--
NOTE: Please delete the word "REMOVE" from my e-mail address when replying.
This is a spam guard.

[Gavin Colbourne 1&1]

How big were your cories when you got them and how big are they now?

Post by RedForeman ©®
cory's aren't peculiar about water changes, but seasonal changes in your tap
water may introduce different water that they may or may not be able to
adapt to... i can't imagine cory's being sensitive after 6 weeks... in the
first few days maybe, but other than initial introduction to a tank, I've
never lost a cory yet...all my cories are over 2 years old...

Post by Dave K.
Over the past couple months, I've had problems with my cory catfish

dying

Post by RedForeman ©®
in

Post by Dave K.
my 20 gallon community tank. I've had one peppered cory in there for
probably a half year now, and he always does fine. But a few months ago, I
bought another cory, he died about three weeks later. I replaced him

with

Post by RedForeman ©®
an

Post by Dave K.
albino cory (from a different pet store), and he's lived for about 6 wks.
But today he was dead at the bottom of the tank... we didn't notice any
problems with him and he has no signs of disease.
Anyway, all our other fish have been doing fine for months. I did notice
that these 2 cories died about 5-6 days after I did a water change. Are

they

Post by Dave K.
more sensitive to water changes than most fish? I usually change about
30-33% of the water every 3 wks. I know it's better to do smaller water
changes more frequently, but isn't changing 1/3 of the water every 3

wks,

Post by RedForeman ©®
as

Post by Dave K.
I do, still pretty good?
Any advice would be appreciated.
--
NOTE: Please delete the word "REMOVE" from my e-mail address when

replying.

Post by Dave K.
This is a spam guard.

[Rick]

Post by Dave K.
Over the past couple months, I've had problems with my cory catfish dying in
my 20 gallon community tank. I've had one peppered cory in there for
probably a half year now, and he always does fine. But a few months ago, I
bought another cory, he died about three weeks later. I replaced him with an
albino cory (from a different pet store), and he's lived for about 6 wks.
But today he was dead at the bottom of the tank... we didn't notice any
problems with him and he has no signs of disease.
Anyway, all our other fish have been doing fine for months. I did notice
that these 2 cories died about 5-6 days after I did a water change. Are they
more sensitive to water changes than most fish? I usually change about
30-33% of the water every 3 wks. I know it's better to do smaller water
changes more frequently, but isn't changing 1/3 of the water every 3 wks, as
I do, still pretty good?
Any advice would be appreciated.
--
NOTE: Please delete the word "REMOVE" from my e-mail address when replying.
This is a spam guard.

I have about 11 different varieties of Cory's and although most are in
species tanks for breeding purposes I do have some Albino and Bronze in
Community tanks. The only one's I have lost are two pigmy hastus Cory's that
got caught between the sponge filter and glass. What other types of fish are
in this tank? Are you feeding the Cory's with some type of bottom type
pellet food. Left to scavenge on their own in a community tank they may very
well die of starvation.

Rick

[Dave K.]

Post by Rick
I have about 11 different varieties of Cory's and although most are in
species tanks for breeding purposes I do have some Albino and Bronze in
Community tanks. The only one's I have lost are two pigmy hastus Cory's that
got caught between the sponge filter and glass. What other types of fish are
in this tank? Are you feeding the Cory's with some type of bottom type
pellet food. Left to scavenge on their own in a community tank they may very
well die of starvation.
Rick

None of the other fish in the community tank is bigger than the catfish or
aggressive at all. We have cherry barbs, zebra and leopard danios, harlequin
rasboras, white clound mountain minnows, etc. All have been peaceful, and
I've never seen any of them pick on another fish.

And yes, we feed the cory catfish shrimp pellets.

Dave K.

[Rick]

Post by Dave K.

Post by Rick
I have about 11 different varieties of Cory's and although most are in
species tanks for breeding purposes I do have some Albino and Bronze in
Community tanks. The only one's I have lost are two pigmy hastus Cory's

that

Post by Rick
got caught between the sponge filter and glass. What other types of fish

are

Post by Rick
in this tank? Are you feeding the Cory's with some type of bottom type
pellet food. Left to scavenge on their own in a community tank they may

very

Post by Rick
well die of starvation.
Rick

None of the other fish in the community tank is bigger than the catfish or
aggressive at all. We have cherry barbs, zebra and leopard danios, harlequin
rasboras, white clound mountain minnows, etc. All have been peaceful, and
I've never seen any of them pick on another fish.
And yes, we feed the cory catfish shrimp pellets.
Dave K.

it's difficult to guess at what the problem might be other than suggest that
you test or have your water tested for PH level. Corydoras prefer softer
acidic water although I do have some in water with a PH around 7.6. If you
notice Corydoras coming to the surface and staying in the upper level of the
tank then that is an indication of a problem. They will surface but should
always return to the bottom. They also when spawning swim up and down the
sides of the tank but again should not stay near the surface for any
extended period of time. They may also come to you with intestinal parasites
which can take weeks to kill a fish . They will normally continue eating
until near the end but should show symptoms such as a sunken belly. Sorry
couldn't help more.

Rick

[~Vicki ~]

I had the same problem with corys a few years ago and found out that it
was a problem in the region with all the LFS's and sick corys. They
were not sure why the mortality rate was so high and thought it may have
something to do with the breeder. I finally got some that have lived
for the last year and breed on a regular basis. The only other
suggestion I have is do more frequent water changes so there is less
shock to the fish. 1/3 is a good amount of water to change in my
opinion, but do the changes weekly instead of every 3 weeks to keep the
dissolved organic compounds (DOC'S) down and thus not stressing the
fish. I certainly hope that this helps you out some and good luck.

Vicki