FAQs on Rasbora
heteromorpha, The Harlequin
Related Articles: Barbs, Danios &
Rasboras, A Barbed Response; Wrongly maligned for being
fin-nippers, barbs are in fact some of the best fish for the home
aquarium by Neale Monks
Related FAQs: Barbs, Danios, Rasboras 1, Barbs, Danios, Rasboras 2, B,D,R Identification, B,D,R Behavior, B,D,R Compatibility, B,D,R Selection, B,D,R Systems, B,D,R Feeding, B,D,R Disease, B,D,R Reproduction,
Harlequin Rasbora / Glass Catfish Breeding
Hi, I wanted to ask you what would you recommend for breeding this
species. They are considered difficult to breed, but they have been
breed in captivity in regularly sized home aquariums. The question here
is what can trigger the spawning?
<Rasbora heteromorpha have been produced commercially for decades... Not
difficult to get to spawn; but taking care in water quality assurance,
foods/feeding are key elements>
I have 11 Harlequins (probably 4 females, 7 males) and 5 Gcatfish. In
forums, it is said that the "rainy season" is the trigger in nature for
both species, that's why they won't breed in a tank.
<These conditions can be simulated... with a pump, plumbing... new water
(rain or otherwise) of slightly reduced temperature>
This is the reason why whenever Rasboras lay eggs, its generally after
big or regular water changes. What do you think about this?
Do you have any method that could help me breed them? (Perhaps something
that worked on other species?)
<Mmm; there are sections of books I have on hand... I've spawned other
not-distantly related Cyprinids... I would have you search with the
terms "Rasbora spawning", accumulating your own notes>
About the glass cats, few cases of reproduction have been reported, and
generally the owner finds the fry accidentally. But this only means it
CAN be done right?
<It has been done; yes. Do you have time to do a bit of searching at a
local college? Read here:
PS: The fish are healthy, mature and some of the female Rasboras have
eggs, but they aren't spawning. Thanks a lot
<An exciting time here! Apply your interest, enthusiasm to investigating
what you're about. Bob Fenner>
Re: Harlequin Rasbora / Glass Catfish Breeding
All right, what would you consider optimal feeding? What has worked for
I think Im getting close with the Rasboras, some females are swollen,
and I saw males harassing them and even trying to get them inverted. I
think some more water changes will do the trick. About the books, what
books where you talking about? I searched the web but there's a lot of
random information, and I'm talking especially about the Glass Cats.
<Step-by-step breeding of Harlequin Rasboras can be found in any book
about breeding fish; for example, I'd recommend "Fish Breeding" by Chris
Andrews. It's inexpensive, widely sold, and contains a couple pages on
breeding all the popular fish. Breeding Kryptopterus is very much hit
and miss. It's been done a handful of times, and there's no step-by-step
recipe yet. A big school of them (20 or more, probably) in a large
aquarium with soft, acidic water and very dim lighting would be the
obvious way to get them settled and happy. Like a lot of catfish they
probably lay eggs more often than we think, but do so when we aren't
watching, at night, and other fish eat those eggs. Websites such as
PlanetCatfish will be the place to ask others who've tried. Cheers,
Hello. I recently added 5 Harlequin Rasboras to my 10 gal tank (which
also houses 1 Honey Gourami and 3 Corydoras). 1 of the Rasboras was
very tiny and I found it dead the next day. The other 4 were schooling
together fine. I then purchased a fifth one because I read they should
be kept in groups of 5, although this one is a little bigger than the
other 4. Now the fifth one is bullying the others and hovering over the
feeding area, and they don't school anymore.
<Do bear in mind that what we call "schooling" doesn't
mean they all get along as friends. Within the group there are intense
Yes, they need company of their own kind as part of their defence
against predators, but each adult is also trying to maximize its
breeding potential, with males in particular jostling over their rank
in the pecking order. In small groups, this can cause serious problems.
Adding more spreads out the aggression, and makes it harder for one
individual to be a bully, because he can't physically harass all
the members of the group all the time.>
The tiniest one keeps a far distance (smart of him I suspect). So I
took the biggest one out to see what would happen, and wouldn't you
know it, the next biggest in size started to mildly bully the others.
Should I try to keep all the same size and return the bigger ones, or
will they eventually work it out amongst themselves? I've had them
for a week.
Thank you in advance, Lorie
<Add another 5 Harlequins, and things should settle down. Cheers,
Re: Harlequin Rasboras Aggressive 9/29/11
So you think 5 more is okay in a 10 gal?
<It's not ideal, but may be the best approach here. You will
have to keep a close eye on water quality, and ideally, upgrade to a 15
or 20 gallon tank as/when the chance arises.>
I thought maybe returning the 2 bigger ones, but I suppose the 3 left
could begin the same behavior?
<Quite so. It's really difficult to predict. Six is often the
magic number of specimens in most cases for them to school at all, with
10 being almost guaranteed to calm down even the more waspish schooling
fish like Tiger Barbs.>
Thanks for your help too! -Lorie
<Glad to help. Cheers, Neale.>
Re: Harlequin Rasboras Aggressive 9/29/11
Hi Neale, how are you?
Lorie here again with the Harlequin Rasboras. Just wanted to update you
on what I decided to do. I ended up returning one of the Rasboras, the
smaller one that was keeping his distance. I noticed his tail lost his
shape and was just a small white fluffy tail. I believe I received a
bad batch of Rasboras, because one died the very next day after I
bought them, and now this one developed fin rot or fungus (my water
parameters are 0 ammonia and nitrite, 10 ppm nitrate, hard water, 80 F
and that's with the heater off).
When I returned him to the store, I noticed another species of fish
that had a large white fungus spot on his back, that shared the tank
with the Rasboras. This really bugs me, because I returned the fish at
night, meaning they had ALL day to notice the sick fish. I don't
understand why they don't at least take it out and put it away in
<Fungus isn't a "catchy" disease as such. It's
usually in ALL aquaria. If you see a bunch of fish with fungus in one
tank, then the most likely explanation is that all the infected fish
are being stressed or damaged in the same way.>
I'm sure it's not cost effective for them to medicate, but at
least remove the sick ones from the water. Ugh! And the associate that
received the fish I returned just left him in the bag on the counter
and proceeded to text and play on her cell phone; so I guess she was
going to let him just die in the bag :( I'm not buying fish from
this chain (PetSmart) anymore. I also noticed another fish being sold
as a Harlequin Rasbora; the shape is the same but the coloring
completely different. It's blue-ish green, no triangle; is this a
Rasbora or another sick fish?
<Difficult to say. There is a Blue Rasbora (Rasbora axelrodi). But
this species isn't much traded. Although a wonderful fish, it needs
very soft and acidic water to stay healthy, so it's a difficult
fish for beginners to keep.>
It was hanging out in the back of the tank and looked off. So back to
my tank; then that left me with 4 Rasboras; well I then returned the
"bully" Rasbora too, just to test out the dynamics. Well the
3 that are left are getting along well. The only time they really chase
each other is when they eat. And 2 of them are showing pre-spawning
behavior by swimming together and the male bumping into her; the female
is so plump I was really thinking she has eggs in her already. I was
thinking of trying to breed them, but from my research, it looks like
even if she laid eggs, they'd die in hard water. The smallest of
the 3 keeps his distance in the back of the tank at times; I hope
he's just taking a breather and another problem isn't ensuing.
I'm keeping my eye on him. But otherwise they will school and they
all eat really well, so I think I'm going to keep it at 3 for
On another note, I have a Honey Gourami. I've had her for 2 1/2
months. She is very active and inquisitive and has a hardy appetite,
but I've noticed recently she will hang out by the HOB filter flow
and breathe air. She didn't do this is the past. I thought maybe it
was a nitrate problem but they were below 10 ppm, ammonia and nitrite
still 0. She still investigates the tank and nibbles on the plants and
decor; I even caught her chasing a peppered Cory all through tank over
a pellet! Never saw her do that before!
So I don't know if I should be concerned; I know they are air
breathers, but she didn't show this behavior until a few weeks
<Various factors affect how often Gouramis gulp air, including water
temperature. The warmer it is, the more air they need. If the fish is
otherwise happy, I wouldn't worry much.>
Physically she looks beautiful, and otherwise acts perfectly normal.
Any thoughts? I just want to say too, I appreciate all the patience you
have for answering all of our beginner questions over and over again. I
find your input extremely informative and helpful! Thank you, Lorie
<Thanks for the kind words. Cheers, Neale.>
Help: Shyness of Blue Rams and Harlequin Rasbora temp
Temp Compatibility For Ram Tankmates 9/1/11
Sorry for the long-winded title!
First, I'd just like to say that I am incredibly impressed with
It is one of the most detailed, comprehensive Aquarium sources I've
ever come across. Thank you for making it so easily accessible to
hobbyists that didn't have this sort of stuff available ten to
twenty years ago.
It's truly a godsend.
< Thank you for your kind words.>
Anyway, I'm starting my tank back up again, and luckily it was
already cycled by four Harlequin Rasbora. It's been up and running
for about two years. I've kept Blue Rams in the past, however have
never been truly successful with them. This time I'm determined.
I've been reading about them constantly. One thing that I know I
never accounted for before was temperature. I would always keep them
around 77F to make the community happy. Not this time. As soon as I got
them into the tank, the water went up to 80F. My question is will this
temperature be ok for the Harlequin Rasboras already in there?
< They should handle 80 F with no problem.>
I plan to get 4 more of them, 6 Cory cats, and a Dwarf Gourami too.
Would all of these fish be ok at this temperature?
< All of these fish would be fine at that temp.>
The Harlequin's seem ok right now, schooling back and forth like
they always do. I know the blue rams would like a temp closer to 82F,
but I want to make it comfortable for the community, so would 80F be ok
for the aforementioned fish?
< When you increase the water temperature the oxygen carrying
capacity of the water goes down. Increase the aeration to compensate
for the increased temps and everything should be fine.>
Secondly, my rams are so shy! I find it adorable, however I'd love
to see them come out and swim around the tank when I'm around. When
I watch the tank form across the room (it's a 30g in my bedroom),
they're picking through the sand happy as can be, swimming with the
Rasboras, and seem generally carefree. However, as soon as I move or
approach the tank, they flee and hide behind the many artificial plants
I have in the tank. Will this get better in time, and is there anything
I can do to speed it up?
< When you get the additional fish they will come up to the top of
the tank to be fed. This will get the rams to also see you as the food
monitor and they will soon learn to come out to be fed.
Too.-Chuck>They seem to be eating, not as much as I'd like,
though, but they do seem to be eating (I'll be picking up some live
or frozen blood worms at the LFS next week on my trip there).
Thanks for any help, and more importantly thanks for hanging in there
while reading this email. I know I tend to drone on. Thanks again!
re: Help: Shyness of Blue Rams and Harlequin Rasbora temp
Rams Start to Color Up 9/2/11
Thank you so much for the prompt reply! I'm relieved I can keep
them all together. I have two more quick questions, if you don't
mind. The two Rams I have are about 1.25" to 1.5" long, I
wouldn't think they are much larger than that. I know they can
reach about 3", but mine are much paler than pictures I see
online. They have colored up some, but is it possible that their color
will intensify once I start feeding them frozen food and they get
< As your fish become more comfortable in their surroundings they
will get more color. Older fish have more color than younger
Also, my two Rams often square up with each other when they run into
one another. Sometimes they'll even lip-lock. However, their
coloring reminds me much more of a female than a male. Could these two
females be showing territorial behavior like the males do? Or are they
just males who haven't quite colored up yet? Thanks so much.
< Rams are very territorial like many cichlids. Their behaviour
could be related to spawning but most likely just establishing
re: Help: Shyness of Blue Rams and Harlequin Rasbora temp
Thanks again for the fast reply! Well, it appears I have another
Today I went to the LFS and picked out 6 green aeneus Cory cats. Upon
putting them in the 36"x12"x18" aquarium, both of the
rams have been non-stop harassing the Cory's.
<Yes, very common. Would have warned you of this! I've mentioned
several times on this site that Mikrogeophagus don't always cohabit
with catfish, and in any case, Mikrogeophagus ramirezi needs much
warmer water than (most) Corydoras prefer. Paul Loiselle describes one
situation where the Ram Cichlids bite the eyes off the poor
The LFS, a forum I go to, and you guys all said they would be fine
so this is very shocking to me. Will this stop in time, or is it
something I should be worried about? What should I do? Thanks so
<Your cichlids view the Corydoras as threats to their brood, and are
acting accordingly. There's no solution beyond separating them.
re: Help: Shyness of Blue Rams and Harlequin Rasbora temp
Upper Tank Mate Recommendations 9/4/11
Sorry for the double email, but I've decided that I'm going to
be taking the Cory cats to the LFS tomorrow and try to exchange them
for a different fish. I want a top dwelling fish. What do you think
would go good in a 30g (36" x 12") with 2 German Blue Rams
and 8 Harlequin Rasbora? I'm trying to balance out the look of the
tank. Thanks for any help!!
< South American hatchet fish or splashing tetras are always found
not too far from the surface.-Chuck>
Stocking established 60L
Yet another question from me, hopefully short and sweet.
Would it be reasonable to add 5 Harlequin Rasboras
(enough for this shoaling spp?) to my established tank? Details
<Should school, be fine>
Tank: 60L rectangular (60cm X 30cm X 35cm), 2 months
old, small internal power filter (quoted 300L/hr max) with sponge and
Temp: 27-28 deg C.
Water parameters: pH 7.2, ammonia 0, nitrite 0, don't measure
nitrate (will soon), GH 4.
Water change regime: 30% weekly (too much?), including gravel vacuum
(half each week) and squeeze of filter sponge in tank water (looking
after the precious bacteria!).
Stock: 7x Melanotaenia praecox, 2x Atyopsis spp
<Oh! Well, this system is already a bit full. I would not add more
beyond the Rasboras>
Sorry if this is all sounding a bit familiar, but I figure you guys
answer enough emails for someone to say "hey remember me..."
and then expect you guys to remember their set-ups as well as their
Anyways, 5 Harlequin Rasboras - yay or nay??
<Yay, with the proviso that you either get another, larger system,
or stop at their addition>
<And you, Bob Fenner>
Re: Stocking established 60L tank 7/5/11
Thanks a lot Bob for your quick reply!
<Certainly welcome Duncan>
I was definitely going to stop at the addition of the
Rasboras - they would complete my tank, as it were.
BUT you mention that the system is "already a bit full". I
would prefer to not get the Rasboras if they are pushing it even a
little - I believe the welfare of the fish should take precedence over
<Mmm, well; now that you've granted me another opportunity to
"spout off" (akin to a baleen whale if you can imagine), I
would like to add that you might consider some other livestock that
would occupy another "niche", area of the tank. The Rainbows
and Rasboras are both mid-water species...
perhaps something more toward the bottom, or surface... that can/will
handle the commotion of the Melanotaeniids>
I know you said yay, but I really want to be sure, and I trust WWM over
any other source of info.
Thanks so much, and you guys and girls are the greatest, at least in
the fish-keeping world!
<Thank you for your kind, encouraging words. BobF>
3/6/08 Hello Neale, I have a question about one of my harlequin
Rasboras. About 6-7 months ago I bought 6 harlequin Rasboras for my 20
gallon planted tank. About 4 months ago I noticed that one of my
Rasboras has a big white spot on the forehead. Now this fish is very
dull in color and very skinny. It eats well but looks like it has
difficulty to swim. All other 5 Rasboras look very well: bright colors,
strong swimmers. I have also in the tank school of cardinals(9 fishes)
that are doing great. Do you have any idea what is that? Thank you for
your help Mark <Hello Mark. Identifying diseases like this is very
difficult without a photo. It could be something as harmless as a cyst,
or more dangerous, like a tumour or parasite of some sort. Given the
fish has lived for several months already but is noticeably less active
than the others, I'd tend towards thinking this is some sort of
tumour or perhaps a viral infection. It isn't likely to spread so
there's no reason to isolate it. My guess is that it will
eventually die, perhaps because the infection will spread to other
parts of the body, much like cancers in humans. Anyway, if you want to
send a photo, please do. Cheers, Neale.> Fish illness,
Rasboras -12/14/07 Hello, I am a bit puzzled since not sure
if I should be concerned or not about my juvenile harlequin Rasboras. I
originally bought 6 baby Rasboras for my cycled but new (1 month) old
10g tank. Now it has been a total of 1.5 months that I had them, 3 died
right away and 3 were left. Out of the 3 one of them had a white
colored anal fin even from the time I brought it back from the LFS
(didn't notice until a few days after). I thought it was fin rot so
treated the tank with Jungles fungus eliminator for 2 weeks.
<Mmmm...> It neither went away or got worse. The fish is acting
and swimming normal and eats fine. The other Rasboras and tankmates are
unaffected. Recently within the past week the whiteness has spread to
the pelvic fin. It is not cloudy nor appearing as a cotton fuzzy
growth. Its like the entire fin is actually opaque white made up of
white pigment (e.g. not just a surface coloring). The finnage is
smaller than it should be, yet has not progressed to complete
deterioration. One side of its body looks like it has cloudy streaks or
haze on it. He does not scratch or have trouble breathing, I don't
think its Trichodina nor fungus... <... not so sure> is there
something else it could be or is it Trichodina or Costia and they take
a long time to develop? <Yes, could be> Is this contagious? How
should I treat? He is acting normal otherwise... <Could be
catching... depending on what "it" is... Do you have a
microscope? Can be blindly treated for with protozoacides...> Tank:
4 Neons 2 Rasboras 4 baby Corys 10gallons pH 7.8 <High...>
ammonia 0 nitrite0 nitrate15 weekly 30% water changes Temp 74 <A bit
low> thanks so much cheers t <Please read here:
http://wetwebmedia.com/FWSubWebIndex/fwmaintindex.htm the sixth tray
down... on FW Disease... There is not much, enough here to "go
on" to suggest much in the way of specific treatment... If it were
me/mine, I'd likely start working on lowering the pH of the water
through modifying the change-out water (over time that is), and raise
the temperature to the upper 70's F... and leave all else as it is.
Photosensitive Harlequin Hi folks
<Denis> I was wondering if you have ever come across a
photo-sensitive fish? One of my harlequins has developed a
strange habit of hanging around with slightly clamped fins near the
surface while the aquarium lights are on. When the lights
are switched off he moves around and feeds as normal. This
has been going on for around a week. The other harlequins are perfectly
healthy and behaving normally. The tank is 180 litre and
very lightly stocked with currently only 4 panda Corys, 4 harlequins
and one female blue ram. The tank is at 79 degrees
and PH is about 6.9 and I am doing 10% water changes
weekly. I recently have added a small amount of peat into
the filter to soften the water. Any suggestions
welcome. Thanks for your time. best wishes Denis Donoghue
<I have seen such behaviour before... in both marine and freshwater
fish species... Wonder what, if any survival value it may portend? Bob
Fenner> Lamb chop Rasbora - a Harlequin Look-Alike
Hello WWM Team, <Hi Craig, Sabrina here, today> Hope you can help
me. I recently bought fish labeled Harlequin Rasbora. The problem is, I
know what a Harlequin looks like and the reason I bought these fish was
they are a Rasbora I have not seen before. I am hoping you can identify
them for me. <Will gladly try!> They have the same colouring as
the Harlequin with some changes. The blue triangle is evident as in the
Harlequin, however, the same blue is also displayed in a very thin line
along the anal area. The iridescent orange is a definite mark confined
to the edge of the triangle and then extending past the triangle
towards the gill in a definite half-circular mark. The remainder of the
body colour is golden .The body is far more slender than the
Harlequin and the fins are all translucent, unlike the Harlequin which
are reddish/orange. The eyes are also golden and not orange...any
ideas? Craig <This sounds unmistakably like the
"Lamb chop" Rasbora, Trigonostigma espei. The
"Harlequin" Rasbora, Trigonostigma heteromorpha, as
you've mentioned, is quite a bit more common in the US, but the
lamb chops do show up a lot. T. espei will only grow to
about half the size of T. heteromorpha, and is a touch more sensitive
as well. More info from FishBase on the
harlequin: http://filaman.uni-kiel.de/Summary/SpeciesSummary.cfm?genusname=Trigonostigma&speciesname=heteromorpha and
on the lamb chop: http://filaman.uni-kiel.de/Summary/SpeciesSummary.cfm?genusname=Trigonostigma&speciesname=espei
. Be sure to make use of all the links throughout those
pages if you wish to learn more detail on the fish, there is a lot of
info there! Wishing you
Rasboras, hlth. 3/6/08 Hello
Neale, I have a question about one of my harlequin Rasboras. About 6-7
months ago I bought 6 harlequin Rasboras for my 20 gallon planted tank.
About 4 months ago I noticed that one of my Rasboras has a big white
spot on the forehead. Now this fish is very dull in color and very
skinny. It eats well but looks like it has difficulty to swim. All
other 5 Rasboras look very well: bright colors, strong swimmers. I have
also in the tank school of cardinals(9 fishes) that are doing great. Do
you have any idea what is that? Thank you for your help Mark <Hello
Mark. Identifying diseases like this is very difficult without a photo.
It could be something as harmless as a cyst, or more dangerous, like a
tumour or parasite of some sort. Given the fish has lived for several
months already but is noticeably less active than the others, I'd
tend towards thinking this is some sort of tumour or perhaps a viral
infection. It isn't likely to spread so there's no reason to
isolate it. My guess is that it will eventually die, perhaps because
the infection will spread to other parts of the body, much like cancers
in humans. Anyway, if you want to send a photo, please do. Cheers,
A question about harlequin Rasbora hi, one of my
harlequin Rasboras died overnight (why do they always die
overnight..?) without a mark on him that I could see, except
maybe the area around his gills was a little red. what might
cause that? this fish has been well established and healthy since late
January or February. I did recently add six cardinal
tetras to the tank a week, week and a half ago of which two died in the
first couple days (poor little guys) and were removed promptly, and the
rest seem to be on their way to being well adjusted.
None of the other fish in the tank (5 additional harlequins and three
Scissortails, and two Otos and a Cory) seem to be unhealthy in any way.
pH reading is very slightly low (maybe 3-4 tenths off at the most, the
color is 'between' two readings) - maybe from fish
waste? I haven't done a water change recently. But the
pH is usually too high anyway (8.4). The fish that have been
there for a while seem to be completely well adjusted to it though so I
don't think high pH would've killed the Rasbora. Well, any
suggestions of what I could look into would be much appreciated, I
really don't like my old fish dying suddenly :( < Most of the
fish you are keeping come from soft acidic water from rainforests. At
the high pH you are running it is hard for these little fish to adapt.
I don't think your cardinals will last too long at that high a pH.
The high pH will not kill your fish off directly but they are
definitely being stressed to the point that they are breaking down.
Start looking at some websites and articles to bring down the pH of the
water to at least the 7 range with 6 being better. I would start by
looking at Marineland.com and look at Dr. Tim's library. These
articles are very informative and will give you some
direction.-Chuck> thanks, ~Anna ps: mailing a separate email with a
question for your freshwater snail folks.
Harlequin Rasboras & schooling at diff. ages Hi, in
January I purchased 6 relatively young harlequin Rasboras. (since then
one died of unknown causes but the remaining five are large happy fish
- maybe 1 inch long although its hard to say due to the refraction of
the water, I would probably guess more like 3/4) There
are also 3 scissortail Rasboras and 2 cardinal tetras (I got six but
sadly 4 of them died, I am going to fix my pH and try to get a
quarantine tank and try again in a month or two), and two Otos and a
Cory in the tank. I'm wondering if I were to get more
young harlequins (I usually see them in the pet store half the size of
the ones I have now or smaller even) if they would be 'safe'
from the older fish, and if they would grow up to school with the older
harlequins? < Schooling fish seem to developed somewhat of a pecking
order. The larger ones will surely push around the smaller ones for
awhile. As long as you introduce a group of smaller ones to the tank at
once then I think you will be OK.-Chuck> Thanks for your help and no
urgency on the reply, I'll be out of town for a few days and its
not like it's an urgent question anyway. :) ~Anna Sick harlequin
Rasboras Help! I have a 10g tank, fake plants, with 2 guppies, 2
Corys, and 4 harlequins. Came home tonight and the harlequins were
hiding, one at the bottom, kind of twitching. I did a 40% water change,
and at first they were all flipping out, but now they seem better. Just
not totally okay. They don't seem to have Ick, no white spots, but
aren't swimming about like they usually do. Someone said they are
depressed because they need more to school properly. What could be
wrong with them? What could I do? < It is true to some extent that
schooling fish are less stressed in a large group but I don't think
that this would cause the sudden reaction that you are seeing. When an
entire group of fish come down with something at the same time it makes
me think of the water quality. I suspect if you checked the ammonia,
nitrites and nitrates you may find that the nitrates have exceeded 25
ppm and the fish were stressed from the poor water quality. This can
weaken the fish and cause disease. I suggest that you check the water
quality and try to keep the nitrates below 25 ppm by servicing your
filter, occasionally cleaning the gravel, not overfeeding, and change
the water to reduce nitrates as needed. -Chuck> Thanks, New Fish
More sick Harlequin Rasboras... Don, Sorry to bother
you again... well, I decided to try what you suggested with one
Rasbora. The water he came in tested at 7.0, my tank tested at 7.4. I
floated the bag and then added about 10% tank water to the bag. I did
this again 20 min later and checked the pH in the bag, and-- surprise!
The pH was 6.4?? Here's my speculation. I'd been adding acid
buffer to the tank pretty much every day up until 2 days ago, in a
futile attempt to keep the pH down. There were enough alkalines in my
tank to check the acid, so the tank basically found homeostasis at
7.4. However, when I added the tank water to the bag, the
acids were no longer checked by the alkalines (presumably the water
from the store wasn't as well buffered), so the pH shot way down.
Sound about right? << Yes (BobF here), very easy to make these
sorts of changes w/o careful understanding of alkalinity AND an
alkalinity test kit>> Well, to make a long story short, I
continued to do 10-20% water changes in the bag, this time with fresh,
un-pH-adjusted water. But after a few of these I realized
that what was happening was that the acids I'd added were
continually bringing the pH down, so basically I was just bouncing the
pH all over the place. Once I realized this, I gave up, pH was around
7.0, I added the fish to the tank, and he is well on his way to dying.
Same symptoms as the others. So now I know what pH shock
looks like. I could do what you suggested, i.e. do water changes until
the tank pH matches the tap pH. The problem is, my tap water
comes out at 8.2. If I add enough acid to neutralize the
water to 7.0 before I add it to the tank, then my tank seems to hold
stable at 7.4. But if I add no acid at all, then eventually
my tank will be at 8.2, right? And that seems awful high for
most fw fish. So what's a guy to do? <I think you got it right.
I was unaware your tap was at 8.2. The easy suggestion is to stock fish
that like your conditions. In your case Mollies or African Cichlids.
But I'm going to ask Bob to comment on this. I'm blessed with
pretty good water (soft at a steady 7.2) here in the Philadelphia area.
You could always move. Don> <<Best to use whatever method to
adjust pH outside your system, in preparation for use... if it has
sufficient buffering capacity (which at a starting/tap of 8.2 I
strongly suspect it does) then lowering (eating up the alkaline
reserve) with an organic or inorganic acid will result in an adequately
buffered (i.e. stable) pH at some "point"... that will tend
to slowly lower over time... due to the reductive (acidic) activities
of small aquatic systems... Please read here re: http://www.wetwebmedia.com/FWSubWebIndex/fwph,alk.htm and make
it known that you (both) understand the concepts of pH,
alkalinity/acidity, and their relation to each other. Bob F>>