Danios: Behaviour and appearance questions
 

So now we have four danios (never go into a pet shop with three
children and the intention to buy two fish). Two are zebra, two are
leopard. They were put into the tank yesterday afternoon.

As of this morning, two of them - one zebra, one leopard - appear
very yellow in colour. I found a photo on-line which showed zebra
danios in both black-and-white and black-and-yellow tones, so
presumably the colouring itself is normal, but is it usual for them
to change colour? They weren't noticeably yellow yesterday. The other
two fish look just the same as yesterday.

Two of them - again, one of each, but not the same pair - seem very
aggressive towards the others, chasing and seeming to nip at them. Is
this normal behaviour?

The non-yellow leopard danio looks fat - would it be noticeable if it
was pregnant? (This is one of the less agressive two, it also seems
to be moving a bit slower than the others, and less interested in
shoaling.)

PH is between 5.0 and 6.0 (bit closer to 6), ammonia is 0 and nitrite
is 0.1.

--
FishNoob

FishNoob wrote:
So now we have four danios (never go into a pet shop with three
children and the intention to buy two fish). Two are zebra, two are
leopard. They were put into the tank yesterday afternoon.

As of this morning, two of them - one zebra, one leopard - appear
very yellow in colour. I found a photo on-line which showed zebra
danios in both black-and-white and black-and-yellow tones, so
presumably the colouring itself is normal, but is it usual for them
to change colour? They weren't noticeably yellow yesterday. The other
two fish look just the same as yesterday.

Two of them - again, one of each, but not the same pair - seem very
aggressive towards the others, chasing and seeming to nip at them. Is
this normal behaviour?

The non-yellow leopard danio looks fat - would it be noticeable if it
was pregnant? (This is one of the less agressive two, it also seems
to be moving a bit slower than the others, and less interested in
shoaling.)

PH is between 5.0 and 6.0 (bit closer to 6), ammonia is 0 and nitrite
is 0.1.

Your pH sounds a little bit low to me. What is it out of the tap? You
might need to take some action on this if this is the tap water - others
will be better qualified to advise on this.

Gill

Thusly FishNoob Spake Unto All:

As of this morning, two of them - one zebra, one leopard - appear
very yellow in colour. I found a photo on-line which showed zebra
danios in both black-and-white and black-and-yellow tones, so
presumably the colouring itself is normal, but is it usual for them
to change colour? They weren't noticeably yellow yesterday. The other
two fish look just the same as yesterday.

This:
http://mikes-machine.mine.nu/specime...o_DSC_0324.jpg
is what a zebra danio looks like.
Leopard danio is believed (it is not certain) to be a breed of zebra
danio, and has much the same base coloration.
Neither are ever, AFAIK, white.

Two of them - again, one of each, but not the same pair - seem very
aggressive towards the others, chasing and seeming to nip at them. Is
this normal behaviour?

Yes. Males are somewhat territorial.

The non-yellow leopard danio looks fat - would it be noticeable if it
was pregnant?

Yes, females are much plumper than males.

PH is between 5.0 and 6.0 (bit closer to 6), ammonia is 0 and nitrite
is 0.1.

That's a low pH. Unless you are breeding sof****er fish like neons,
you'd have greater margin of safety if you put a couple of limestones
in the tank (which'll buffer the water and give a pH of 7.5). Now, 5
isn't lethally low, but many fish will have problems reproducing at
that pH, and at 4.5 some fish will start to die. You also can not keep
snails or shrimp at a pH under 6.

Mean_Chlorine wrote:

This:
http://mikes-machine.mine.nu/specime...o_DSC_0324.jpg
is what a zebra danio looks like.

That's a great picture! I've never had my long-fin zebras stay still
long enough to get a shot like that!

FishNoob wrote:
So now we have four danios (never go into a pet shop with three
children and the intention to buy two fish). Two are zebra, two are
leopard. They were put into the tank yesterday afternoon.

ROFL! My BF is like that in fish stores. You'll be fine with four danios.

As of this morning, two of them - one zebra, one leopard - appear
very yellow in colour. I found a photo on-line which showed zebra
danios in both black-and-white and black-and-yellow tones, so
presumably the colouring itself is normal, but is it usual for them
to change colour? They weren't noticeably yellow yesterday. The other
two fish look just the same as yesterday.

Fish like danios subtly change colors all the time. They tend to go
pale when stressed and darken when they're content. Some fish will show
or lose stripes as well. If a bunch of fish in your tank suddenly go
pale and still, they're "telling" you that something is amiss.

Two of them - again, one of each, but not the same pair - seem very
aggressive towards the others, chasing and seeming to nip at them. Is
this normal behaviour?

The non-yellow leopard danio looks fat - would it be noticeable if it
was pregnant? (This is one of the less agressive two, it also seems
to be moving a bit slower than the others, and less interested in
shoaling.)

It's either carrying eggs or unwell. In many small, shoaling species,
male fish are thinner than females and often have slightly deeper color.
If the fat fish's scales start to stick out from its body, it is sick
with a disease called "dropsy." Let's hope that's not the case.

PH is between 5.0 and 6.0 (bit closer to 6), ammonia is 0 and nitrite
is 0.1.

Your water must be very soft. There IS an advantage to having a low pH
while your tank cycles. Ammonia is much less toxic at low pH. However,
bacteria don't grow very well below pH 5.5. If there is not much
ammonia yet, I'd try to gently raise the pH to around 7.

In the short term, since there's no ammonia, add 1/4 US tsp (there's
about 5 ml of volume in a US teaspoon; I don't know how many grams) of
predissolved baking soda (sodium bicarbonate, bicarbonate of soda,
bicarb) to your tank today. The pH and KH will rise and then fall again
over the next 24 hours.

Test pH and ammonia again tomorrow. If pH isn't up to 7 or higher and
ammonia stays below 0.5 ppm (it should since you have some nitrite but
you never know), add another 1/4 tsp of baking soda. This *should* be
enough baking soda, but you can repeat this for two more days if necessary.

In the long term, you have a couple of options. For a planted tank, use
a buffer like Seqchem's Equilibrium when you change water. It's
designed to set the pH at 7.0 and supply essential nutrients for plants.

Another easy, natural way to control pH is to put a form of calcium
carbonate in the tank or filter. It will slowly dissolve and increase
both the general hardness and pH (carbonate hardness, to be more
precise) with no fiddling on your part. Seashells, crushed coral, or
limestone all work. The more you add, the higher the pH will go, up to
a maximum of 8.4. Livebearers in particular appreciate water that's
been hardened with limestone.

Finally, you can keep using baking soda, adding more when you change
water. You can do this if you end up choosing a tank full of soft water
fish and don't need a buffer like Equilibrium.

--
Elaine T __
http://eethomp.com/fish.html '__
rec.aquaria.* FAQ http://faq.thekrib.com

Thusly Guido Spake Unto All:

This:
http://mikes-machine.mine.nu/specime...o_DSC_0324.jpg
is what a zebra danio looks like.

That's a great picture! I've never had my long-fin zebras stay still
long enough to get a shot like that!

Glad you like it; zebras are so hyperactive it took me ages to get a
decent shot, and it's still not as good as I'd like.

It came as a surprise to at least me that zebras have so much blue on
them.

In article ,
says...
PH is between 5.0 and 6.0 (bit closer to 6), ammonia is 0 and nitrite
is 0.1.

That's a low pH. Unless you are breeding sof****er fish like neons,
you'd have greater margin of safety if you put a couple of limestones
in the tank (which'll buffer the water and give a pH of 7.5).

So it's okay to put some limestone in? I read some websites that said
that rocks were okay to add as long as they *weren't* limestone, so
we collected some rocks and tested them. We set aside those that
contained limestone, but there are a couple of great ones (the kids
particularly like the one that looks like a fossil of an alien's head
G), so if we *can* use them...

I also read somewhere (thought it was here, but can't find it here
now) that placing some seashells in the tank will increase the ph. I
can find a few websites that offer that advice - eg
http://www.fishtanksandponds.net/set...tank_decor.htm -
but other websites that say "under no circumstances". Opinions
please...

(Hoping that it's okay, because after I read it and before I read not
to do it, we went off seashell-collecting today LOL. If it *is* okay,
how many seashells are we talking? Most of those we've got are an
inch across or less. We also got some that look like snail-shells -
empty ones! - is it the same for them?)

This is a really good interest for someone who loves to learn LOL

--
FishNoob

Thusly FishNoob Spake Unto All:

PH is between 5.0 and 6.0 (bit closer to 6), ammonia is 0 and nitrite
is 0.1.

That's a low pH. Unless you are breeding sof****er fish like neons,
you'd have greater margin of safety if you put a couple of limestones
in the tank (which'll buffer the water and give a pH of 7.5).

So it's okay to put some limestone in? I read some websites that said
that rocks were okay to add as long as they *weren't* limestone

Yeah, that's because most websites don't know anything at all about
water chemistry, and simply quote eachother and/or books by authors
who don't know anything about water chemistry either, therby
perpetuating a whole range of myths.
Limestone in water will neutralize acid, and raise pH. Most of our
fishes come from water with a pH of about 6 - 8. This much everyone
know. What the websites etc miss is that the dissolution of calcium
carbonate has an endpoint at 8.3 (which, incidentally, is a 100% safe
pH), and that the process speed decreases the closer you get to 8.3,
so the actual pH in an aquarium filled with limestone will stabilize
around 7.5. That is, you _can not_ kill your fish by raising pH with
limestone. You will never reach dangerously high pH's. Ever.

Then there's the issue of "the right pH". The importance of, and the
sensitivity of fish to, pH is monstrously exaggerated in aquaristics.
Fact of the matter is, pH 7.5 is _perfect_ for every freshwater fish
on this earth EXCEPT if you're breeding (and I do mean breeding, not
just keeping) blackwater fish like neons or if you're a high-tech
plant aquarist who want maximum amount of free CO2 in the water. The
reason you may need to lower pH when breeding blackwater fish is
because the fish may use low pH as a trigger for spawning, or the egg
membranes may become impermeable to the sperm. The adult fish' health
is completely unaffected.

Every fish on earth, including the marine ones, will also greatly
prefer a stable pH over a fluctuating one, and the limestone will make
the pH stable.

In your case, with your very low pH, a limestone (or shells etc) may
actually be a lifesaver for your fish.

I also read somewhere (thought it was here, but can't find it here
now) that placing some seashells in the tank will increase the ph. I

Yes, anything that's made of calcium carbonate: shells, fossils,
limestone, chalk, even eggshells, but NOT blackboard chalk (that's
calcium SULPHATE, aka gypsum, and will not buffer pH at all).

FishNoob wrote:
In article ,
says...

PH is between 5.0 and 6.0 (bit closer to 6), ammonia is 0 and nitrite

is 0.1.

That's a low pH. Unless you are breeding sof****er fish like neons,
you'd have greater margin of safety if you put a couple of limestones
in the tank (which'll buffer the water and give a pH of 7.5).


So it's okay to put some limestone in? I read some websites that said
that rocks were okay to add as long as they *weren't* limestone, so
we collected some rocks and tested them. We set aside those that
contained limestone, but there are a couple of great ones (the kids
particularly like the one that looks like a fossil of an alien's head
G), so if we *can* use them...


I keep a small bag of "crushed coral" - i.e. limestone - in each of my
filters. It's to add some alkalinity (carbonate hardness) and buffer pH.
That's because my city water is soft, about 35 ppm (total hardness or
carbonate hardness - the test kit is not clear which it measures). The
crushed coral/ limestone gives me about 80 ppm "hardness" and a pH of
7.1 to 7.3, so I can be confident there will be not pH "crashes" toward
acidity.

Using carbonate in the filter is recommended by several aquarium books
I've read. Using pieces of limestone should be pefectly all right,
unless you want low hardness and acid conditions.

I think that rocks to be avoided are those containing sulphide or
arsenide minerals (pyrite, arsenopyrite...), and perhaps sulphates (gypsum).

I hope you keep having fun with the aquarium!

Steve

Mean_Chlorine wrote:
Thusly FishNoob Spake Unto All:


PH is between 5.0 and 6.0 (bit closer to 6), ammonia is 0 and nitrite

is 0.1.

That's a low pH. Unless you are breeding sof****er fish like neons,
you'd have greater margin of safety if you put a couple of limestones
in the tank (which'll buffer the water and give a pH of 7.5).

So it's okay to put some limestone in? I read some websites that said
that rocks were okay to add as long as they *weren't* limestone


Yeah, that's because most websites don't know anything at all about
water chemistry, and simply quote eachother and/or books by authors
who don't know anything about water chemistry either, therby
perpetuating a whole range of myths.
Limestone in water will neutralize acid, and raise pH. Most of our
fishes come from water with a pH of about 6 - 8. This much everyone
know. What the websites etc miss is that the dissolution of calcium
carbonate has an endpoint at 8.3 (which, incidentally, is a 100% safe
pH), and that the process speed decreases the closer you get to 8.3,
so the actual pH in an aquarium filled with limestone will stabilize
around 7.5. That is, you _can not_ kill your fish by raising pH with
limestone. You will never reach dangerously high pH's. Ever.

You've got me curious because I've not seen pH stabilize around 7.5 when
I fill a tank calcium carbonate. I've always had hard, high pH
tapwater, though. When I stuff a tank with carbonates, it's usually for
marine fish or Tanganyikan cichlids and with hard water to start with,
the pH generally ends up above 8.0. If you have time to elaborate on
the equilibrium chemistry for soft water or have a link, I'd enjoy
taking a look.

--
Elaine T __
http://eethomp.com/fish.html '__
rec.aquaria.* FAQ http://faq.thekrib.com