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Jordanella floridae (American-Flag Fish)


  1. a comparison of two algae-eating fish
    by "Roger S. Miller" <rgrmill/> (Wed, 22 Mar 2000)
  2. comparison of two algae-eating fish
    by "Roger S. Miller" <rgrmill/> (Wed, 22 Mar 2000)
  3. Flag Fish chasing Apisto's question
    by Biplane10/ (Tue, 16 May 2000)
  4. Availability of Florida Flag Fish
    by Wright Huntley <huntley1/> (Mon, 22 May 2000)
  5. American Flag Fish
    by "Cathy Hartland" <hartland/> (Wed, 26 Jul 2000)
  6. American-Flag Fish
    by jazerjo/ (Wed, 26 Jul 2000)
  7. Miller's FFF Musings
    by "Roger S. Miller" <rgrmill/> (Thu, 22 Feb 2001)
  8. shrimps, flagfish and barbs etc
    by Thomas Barr <tcbiii/> (Thu, 22 Feb 2001)
  9. Miller's FFF Musings
    by "Cathy Hartland" <hartland/> (Fri, 23 Feb 2001)
  10. American Flag Fish Observations.
    by "Bailin Shaw" <bailin_shaw/> (Fri, 23 Feb 2001)
  11. Excuse me. I hate to interrupt a good fight...
    by Wright Huntley <huntley1/> (Fri, 23 Feb 2001)

a comparison of two algae-eating fish

by "Roger S. Miller" <rgrmill/>
Date: Wed, 22 Mar 2000


Traffic on the list has been real light lately, so I guess I'll wade in
with an unsolicited post.

A few months ago I rebuilt two 10-gallon tanks that I previously used
partly for comparitive experiments.  I posted a letter at that time
describing some of my experiences with the two tanks.

When I rebuilt the tanks I gave them identical equipment and substrates,
similar plant densities (but not identical plant species) and similar
maintenance. I populated one tank with four American Flag fish (Jordanella
Floridae) ranging in maturity from small juvenile to full adult and one
with three female adult swordtails (the venerable Xiphophorus helleri).
Both fish eat some types of algae.  The plants used in both tanks carried
some algae from the previous setups and it was soon evident that there
were considerable differences between the ability (or will) of the fish to
remove the algae.

Diatoms grew in both tanks and none of the fish showed an interest in
picking at the brown film.  Plants in both tanks carried small but
noticable infestations of green hair algae, black brush algae and beard
algae.  A coarse dark algae I would call staghorn algae and a fine, short
filamentous black algae appeared later in in both tanks.

The Flag fish quickly removed all signs of the green hair algae from their
tank.  The staghorn algae made a brief appearance in the Flag Fish's tank
then disappeared.  I never saw them eating it, but who can say what they
might do when my back is turned?  The beard algae also made a brief
appearance and then disappeared.  I think I've seen Flag fish eating beard
algae before, but I don't know in this case if the fish removed it or if
the algae simply failed to thrive in the new setup. The Flag fish showed
no interest in the black brush algae and it grew on older leaves from a
small presence to very noticable bushy clumps.  The black brush algae
didn't appear on new leaves and I eventually removed the older leaves, so
now it's gone.  The Flag fish also show no interest in the fine, dark
filamentous algae and that is starting to become a nuisance on some older

The swordtails removed every sign of black brush algae from the older
leaves in their tank.  They also grazed on the green filamentous algae --
enough to keep it in check, but not enough to eradicate it.  I removed the
little bit they left.  Beard algae and the short, black filamentous algae
both made brief appearances in the tank and then disappeared.  I think
that swordtails grazed both types of algae, but I can't say how much of
the algae's disappearance was caused by grazing and how much might have
been due to the algae's failure to thrive in the tank.  The swordtails may
have nipped at the staghorn algae a little but otherwise they showed very
little interest in it.  The staghorn algae is now gone; I think that once
the tank got established that the staghorn algae simply failed to thrive.
The swordtails' tank is now pretty-much algae-free.

Both types of fish will eat plants.  The swordtails nipped the ends off
the fine leaves of R. wallichii; their constant nipping and cleaning also
uprooted some pearl grass (graciously given to my by Tom Barr) and made it
a little difficult to get the pearl grass started, though that problem
seems to be over now.  The Flag fish turned out to be real fans of dwarf
hair grass (also donated by Tom Barr) and I suspect they would have gone
for the R.  wallichii with at least as much gusto as did the swordtails.
The Flag fish also tattered the edges of C. wendtii leaves and I've seen
Flag fish in other tanks do the same thing to Val. americana leaves.

In my tanks the female swordtails did a better algae-eating job than the
American Flag fish - even cleaning up the dreaded BBA.  At this point the
swordtail tank is pretty much clean but I still have a little problem with
a short dark filamentaous algae in the Flag fish tank.

Roger Miller

comparison of two algae-eating fish

by "Roger S. Miller" <rgrmill/>
Date: Wed, 22 Mar 2000

I'm responding to my own post, even before it hits the digest.  This is
bad. Very, very bad.

I wrote the original post from my office, finished my day's work, cruised
by a PTA meeting and headed home to find a juvenile Flag fish concertedly
ripping away the short dark filamentous algae that the Flag fish had
previously never touched.  In another day or two at the rate the little
guy is going there won't be a speck of it left.

Roger Miller
in temporarily soggy Albuquerque.

Flag Fish chasing Apisto's question

by Biplane10/
Date: Tue, 16 May 2000

I've found male flagfish can be a bit aggressive when they were first 
introduced to a community tank.  This was really 1 of 3 males, I guess the 
boss guy. It chased whatever it could go after. After probably 1 week, he 
stopped harrassing. I recall adding some other fish that might have put him 
in his place. (A betta temporarily?)  I don't think they are very aggressive 
fish. I think initially it might be a stake for territory (food). Probably 
starving from the lfs. I feed them well and they're quite friendly now. When 
I had no females in this tank, he was getting very friendly with a female 
blue ram in there, rubbing his body along hers and following her everywhere. 
Now that I've put some female flagfish in, he pretty much keeps his 
affections to his own kind.


> I've added a pair of american flag fish to my 25 gallon (planted angel and 
>  apisto) tank,
>  my flag fish seems to chase everything in my tank? is this common? i 
>  they were peaceful, fm what i've read off the net...
>  or is it something i'm doing wrong?

Availability of Florida Flag Fish

by Wright Huntley <huntley1/>
Date: Mon, 22 May 2000

> Date: Mon, 22 May 2000 04:32:14 -0400
> From: Dwight <>
> Subject: Re: Availability of Florida Flag Fish

Please drop that name before the situation gets any worse.

> Ask your LFS to try another supplier.  FFF are an inexpensive, native
> species to the US.  Unlike so many other fish in aquaria, they  are not
> inbred so they have high disease resistance.  Don't forget to tell the LFS
> guy their scientific name.

That will do every bit as good as giving the wrong common name (FFF).
Distributors and fish shops refuse to use scientific names -- ever. [Well,
almost always...]

The correct common name for *J. floridae* is American Flag Fish. If you want
*real* picky, it should be American-Flag Fish, the compound adjective is
because the males vaguely resemble our US flag.


PS. Inbreeding and disease resistance have a near zero coefficient of

- -- 
Wright Huntley, Fremont CA, USA, 510 494-8679  huntleyone at home dot com

         "DEMOCRACY" is two wolves and a lamb voting on lunch.
     "LIBERTY" is a well-armed lamb denying enforcement of the vote.
             *** ***

American Flag Fish

by "Cathy Hartland" <hartland/>
Date: Wed, 26 Jul 2000

Marci wrote:

> Date: Tue, 25 Jul 2000 16:49:52 -0700
> From: Leonardo <>
> Subject: Flag fish
> Kevin Z. brought up flag fish, after hinting that he would like
> feedback...
> Well, here ya go!
> I see these flag fish mentioned all the time.  I can't track down in any
> book the common name flag fish, and I have no idea what they are, though I
> would love to find out.  So, Kevin, would you describe them for me? Anyone
> have a pic they would send me, or a scientific name, or a west coast
> colloquial name I might recognize the fish by?
> (Something tells me these fish are gonna turn out to be guppies....)
> Marci

Dwight has unfortunately mentioned these fish as Florida Flag 
Fish. The actual common name is American Flag Fish (the male 
has the coloration of the American Flag - not the Florida flag). Latin 
name is Jordanella floridae. They are not guppies. They are native 
to Florida, hence the species name. Flag fish are very effective at 
eating filamentous algae, and they are IME peaceful community 
fish which stay smaller than SAEs. You can see a photo of the 
female at this site:

Cathy Hartland
Middletown, MD

American-Flag Fish

by jazerjo/
Date: Wed, 26 Jul 2000

Actually, just to be a bit more pinnikety on the 
American-Flag fish (not Florida Flag Fish) topic.

It's supposed to be written American-Flag Fish
with the hyphenation between American and Flag
as it is an American Flag ..... Fish,  not an
American  FlagFish. People think of it as a 
Flag Fish... which of course it isn't. It looks
like an American Flag, so hence it's an
American-Flag fish.

K, nuff said.

- --------------------------------------------------
Kite Flyers Are Outstanding In Their Field
Visit The Power Kite Site

Miller's FFF Musings

by "Roger S. Miller" <rgrmill/>
Date: Thu, 22 Feb 2001


Before going any further, I'd like to get two things straight.  First, I
wasn't musing, I was stating experience.  Second, let's all remember that
Dwight *sells* American-Flag fish, so his reply may be a matter of
protecting a vested interest and not a matter of trying to get the truth

On Thu, 22 Feb 2001, Dwight wrote:

> So...if you were fully aware of the fact that single-sex arrangements of
> Females and Non-breeding males or Females w/ juvenile males are in fact the
> ones to make good community fish or "reasonable tank partners" as you
> grudgingly described it, then why the H*** did you put those fancy male
> guppies in with adult male and female FFF?!  Just what did you expect?
> Doesn't that seem contradictory?

Gee, Dwight, I wasn't really aware of all this until *after* I put the
guppies in the tank with the flag fish.  It was a true learning

> To the best of my knowledge, Dwarf Cichlids [for example] mostly make good
> community fish.  Yet we all know how aggressive and territorial they all
> get when they are breeding. Do we thus abandon them to Cichlid only tanks?
> Nonsense!  Instead we prevent them from breeding so we can enjoy them w/
> other inhabitants.  FFF breed much more easily than do Dwarf Cichlids and
> the male becomes aggressive once courtship begins.  Knowing this, separate
> mature males from females if you want community aquarium harmony.  Check
> out this article by our own Wright Huntley:

I wouldn't advise anyone to keep dwarf cichlids in a community tank; they
aren't particularly good community fish.  I think we all like observing
the breeding and brooding behavior of our fish.  It would really be a
shame to keep dwarf cichlids without keeping them together.  The same
thing can be said for flag fish.  Their breeding and brooding behavior is
interesting and the male's colors are truly beautiful when he's breeding.
Non-breeding females and juveniles are pretty doudy fish.

The flag fish were not breeding at the time they tore into my
guppies.  So it appears that flag fish can be aggressive even when not

> Miller says:
> >  I do have problems with >a tough short-haired algae that hugs the
> >substrate and thrives in dim
> >light.  They don't do much at all about that stuff.
> A "Tough-Short-haired-algae".."Thrives in dim light".. Doesn't that sound
> like STAGHORN algae or some BBA variant?  Whoever heard of TOUGH hair
> algae??  Personally, I've never had a problem w/ this algae so I can only
> go on what others told me:  The FFF will nip the ends off of this stuff
> (some say they don't).  They can't remove what's left (all agree).  I'm
> told this does have a deleterious effect on that algae, but the FFF don't
> really dig it.

It is a green algae, probably what Diana Walstad describes as "mat" algae.
It likes to grow on the substrate and it gets tangled up in carpet plants.
It isn't BBA or any other sort of red algae.  If you haven't run into,
then count yourself lucky.

> Now, I'm totally confused with the inherent contradictions in your musings.
>  First, you seem to suggest they don't eat the hair algae then you say the
> effectively remove it.  Which is it?  Besides the fact that few people have
> ever reported Ruby barbs consistently as "effective Algae eaters" (which
> algae?) the nebulousness of your first "algae" description can be
> interpreted several ways.

Only you could be confused by this, Dwight, and then only for some
self-perceived rhetorical advantage when you're trying to debate a point.
They removed the long, soft hair algae -- which wasn't much of a problem
to start with -- and they don't touch the short, tough hair algae that is
a problem in that tank.  They also damaged a lot of plants.

Some time ago (last year,I think) I gave a detailed description and
comparison of two recently setup tanks, one with flag fish and one with
female swordtails. The flag fish damaged the plants in their tank enough
that the plants couldn't get established before algae got a foothold in
the tank.  Their plant-damaging behavior actually caused the algae problem
in that tank.

I'm not reporting ruby barbs as consistent and effective algae control.
I'm reporting that ruby barbs did a better job than flag fish.  Female
swordtails also did a better job than flag fish.  What should I test them
against next?  Mollies?

Is there anyone out there who *doesn't* sell flag fish that want's to
stand up and tell us what a great community resident flag fish are, or to
tell us that they really are great at controlling algae?

Roger Miller

shrimps, flagfish and barbs etc

by Thomas Barr <tcbiii/>
Date: Thu, 22 Feb 2001

The recent talk on Florida flagfish for hair algae herbivory has not
convinced me that they are good at it. I had them sometime ago. I was not
too awfully impressed personally but others had mentioned successes. Most
were unimpressed and a few said they did nothing for their algae problem. I
fell into this group myself. Much of what Roger said mirrored a time or two
that I had. Neil Frank had them so I tried them for some time way back when.
But Rosey barbs kick their butt in this area. But roseies were going after
my Riccia etc. Or anything else fluffy or fuzzy. Still a pretty fish and
quite active if not intense. But they are often a temporary animal in some
tanks due to this. Flagfish can/could be used in a similar
fashion(temporary). Rosey barbs are a better community animal IMO hands
down. Hard to catch though in a fully planted tank! But you can get the long
finned types that are slower and easier to catch. But flag fish can have
their place also.
But having a massive school of flagfish? That will cause problems. The Rosey
barbs are schooling fish naturally. Put 12 in a 100 gallon tank and they
will clean it out fast. No sexual aggression happening etc. Say good by to
your Riccia stones and moss though. They are much nicer to see than the
flagfish IMO. Nice cherry silver red color. Some varieties are very intense
and have slightly different markings.

If you want an active tank and have no moss/Riccia etc have a semi
aggressive tank where a shrimp may be eaten these guys area good solution
for hair algae.

Shrimps will not bother any plant or any fish though. They will sit out and
hang on many species of algae picking away. I recently add a big glob of
hairy scum to a tank. The shrimps where all over it like dung beetles on know. It was gone by the next morning. They are cheap if you look
around or try to get more than 6 on a deal or group buy. They are not tough
regarding water quality like flagfish and then the rosey barbs but if you
have a good handle on your CO2 and have some water circulation in your tank,
do water changes this is not a problem. SAE's will chew on some species of
hair algae. SAE's while good and great for specific types of algae do attack
one plant that I know of, Rotala wallichii. I've watched do it many time by
many different SAE's. Not just "my two fish" or once or twice or three times
Shrimps and snails seem to be the clear winners for herbivory.  They don't
attack plants at all and don't bug other fish. Now the fish might bug them
But Flag fish are over rated and not the most effective hair algae remover
in tanks I have messed with. They get 3 out of 10.

But you can use the nutrition, CO2 and picking at the algae methods also.
This is the long term solution to any algae. The herbivory crew is just
icing on the cake to make sure new algae don't appear. No animal is going to
cure bad conditions.
Another note on hair algae. There are many species of hair algae. Some much
worse than others.
Tom Barr

Miller's FFF Musings

by "Cathy Hartland" <hartland/>
Date: Fri, 23 Feb 2001

Roger Miller wrote:
> Is there anyone out there who *doesn't* sell flag fish that want's to
> stand up and tell us what a great community resident flag fish are, or to
> tell us that they really are great at controlling algae?

That would be me. I have a pair (male/female) of American-Flag 
Fish in my 30 gallon community tank. At the time they were 
introduced (about a year ago), the tank had serious green algae 
problems (thread and fur). I had begun to control it via nutrient 
balance. When the flag fish were added, they hid for the first week. 
Then they started in on the algae. First all the thread algae 
disappeared. Then they went to work on the tougher fur algae 
(Oedogonium). Eventually that too disappeared. Now I see them 
nibbling here and there on the driftwood or anubias, picking off what 
little they can find. They sometimes nip at the micranthemum, but I 
can assure you that they do no noticeable damage. They don't eat 
food from the surface, but devour sinking pellets. The female is 
especially voracious for both algae and pellets. The male is very 

So far they have been model citizens in the tank, keeping to 
themselves and bothering absolutely no one. I have rasboras, 
various small tetras, pygmy cories, and an SAE in the tank too. At 
no time have I ever seen any aggression. Let me also note that this 
pair has not bred as far as I can tell. If they do, they must pick a 
deeply hidden part of the tank where no other fish go anyway (not 
hard to do in this densely planted tank). 

Like Dwight, I have been promoting the keeping of these fish for 
algae control, to anyone who asks. It would appear that the 
personalities of these fish are highly individual. However, if you find 
a mild pair, they are excellent for algae control in a planted tank. 
Perhaps Dwight could breed for mildness?

Cathy Hartland
Middletown, MD

American Flag Fish Observations.

by "Bailin Shaw" <bailin_shaw/>
Date: Fri, 23 Feb 2001

Hello APDer's,

With all of the recent talk about the "American Flag Fish", I wanted to 
pitch in my experiences with this little terror.  After reading about how 
the fish could be ideal for removing algae, I decided to purchase a pair of 
females to try and control BBA in one of my tanks.  At the time I had some 
beautiful Angelfish in this tank and the tank was very heavily planted.  
This particular tank was my pride and joy.  Well, everyone knows the story 
about how troublesome these little fish are.  My angelfish's tails were 
mangels in about a week and numerous plants were stripped down to the stems. 
  Now, I thought that this was due to the fact I don't feed as often as I 
should to keep algae in check.  So, I increased the frequency of feedings 
and made sure I noticed that the American flag fish got their fair share of 
the food.  It do absolutely NO good.

In about two weeks, I had lost about half of my plants and my angelfish were 
sick and the tails heavily damaged.  Needless to say, I was distraught.  I 
never thought that the fish were responsible, instead thinking that the 
pleco had gone on a rampage.  That was until I watched the American flag 
fish tear a chunk out of my angelfish's tail and tear pieces of a large 
Amazon sowrd plant.  That was when I decided that the two had to go back to 
the pet store.  I traded for some nice peaceful ottocinclus catfish instead 
and my fish and plants in the tank were much happier for it.

So, to me it's obvious that these fish were not designed for long term algae 
control.  I was very displeased with these fish and wouldn't recommend them 
for algae control.

Bailin Shaw

Excuse me. I hate to interrupt a good fight...

by Wright Huntley <huntley1/>
Date: Fri, 23 Feb 2001

> Date: Thu, 22 Feb 2001 20:10:00 -0600
> From: zxcvbob <>
> Subject: Excuse me. I hate to interrupt a good fight...
> How can I tell whether *my* flag fish is a female, or a juvenile male? 
> I haven't found any pictures on the WWW.  The fish has a definite spot
> on its sides, and a little red coloring that seems to come and go for no
> apparent reason.  Sometimes the fish has little or no red or bluish
> coloring, but has kind of a checkerboard pattern. All of the colors are
> quite subdued, but the fish is still stressed out, so may not be fully
> colored yet.  It is less than 2 inches long including fins.

American-Flag Fish are easy to sex from a very early age. They all look like
females until starting to sexually mature, but only females get the crisp
dark eye-spot in the dorsal fin. It shows much earlier than other sex
indicators, AFAIK.

It sounds like you have a female, but you can be sure if the dorsal fin has
a strong black spot. Mature females have the big spot below the front of the
dorsal, in the middle of the side, but they often echo it several times back
toward the tail. I have only seen females do the checkerboard bit.

> Either way, will the fish do OK as the only flag fish in the aquarium if
> I get a pair of mollies to keep it company?

Sure, but as both are vegetarians, you will need to feed the sinking wafers,
blanched zucchini chunks, etc. or your plants could suffer. I've never known
a *Jordanella floridae* to bother plants until starved for veggies, with one
exception. A displaying male will sometimes bite a big chunk out of a leaf
to show how tough he is. Otherwise, you can be pretty sure your feeding
isn't correct if they bother your plants. There could be exceptions I'm
unaware of, but I've had them with several of the plants mentioned here as
being eaten by them, and they did not eat mine if I had enough vegetable
matter in their diet to begin with. [Too many veggies, and they may not be
eager to eat bitter algae, tho! :-)]


- -- 
Wright Huntley, Fremont CA, USA, 510 494-8679  huntleyone at home dot com

              Politicians and diapers have one thing in common. 
                 They should both be changed regularly 
                       and for the same reason.


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