Silver Dollars Behavior
Related Articles: Serrasalmine Fishes, Piranhas, Characoids/Tetras &
FAQs on: Silver Dollars (Metynnis, Mylossoma,
Myleus...spp.) 1, Silver Dollars
Silver Dollar Feeding,
Silver Dollar Health,
Silver Dollar Reproduction, Related
biting Myloplus rubripinnis 11/25/13
I searched for two hours for info re: my problem. You are my last hope.
I have a pair of red hooks (Myloplus rubripinnis) in a 55 gallon
<Mmm, really need more specimens... like most Serrasalmines, these
"silver dollars", live in schools; and much more room for them>
with 3 African Clawed Frogs,
<Mmm, must be hard to feed here>
1 Convict, 1 plecostomus, and 1 apple snail.
The larger red hook has bitten the smaller red hook on both sides with
vigor. The smaller red hook is missing a lot of skin.
<Again; to re-emphasize... need to be kept in a group (dilutes
aggression) and bigger world (ditto)>
Is there anything I might use to treat these injuries?
<Mostly just moving them to a larger system>
Could I add some kind of sedative to the water to calm the large red
<Mmm, no; not really>
Do they make Ritalin for fish? Ha!
Should I get two more red hooks?
<Three would be better; but only in a hundred plus gallons>
The large red hook is aggressive with everyone in the tank.
I am feeding everybody red worms.
Ph and temp. are normal.
Thank you for any help you might offer.
<I do hope yours recovers... Have you searched, read what is archived on
WWM re these fishes? Bob Fenner>
Re: biting Myloplus rubripinnis
Thank you, Bob.
Silver Dollars chasing each-other 12/29/12
I have 5 Silver Dollars in a 7ft tank with two Oscars, one Jack Dempsey,
one Featherfin Catfish and one Shark fin Catfish. I know it sounds like
a lot in one tank but their all pretty peaceful, the Oscars do fight
from time to time, which is normal. The only problem is my Silver
Dollars chase each-other like there's nothing else to eat.
<What they do>
Also their not vegetarians they love bloodworms and crickets.
<Ah yes... are part of the same subfamily as the Piranhas
(Serrasalminae); are omnivorous>
<As you state; this size, shaped system should be fine for all you
list... as long as the Oscars aren't breeding! Bob Fenner>
Re: Silver Dollars chasing each-other 12/30/12
Thank you for answering so quickly. My Silver Dollars look like their
fighting for territory, also they have small bite marks on their side
but they don't seem to be biting each-other.
<Mmm, well they do... as you state, territoriality mostly... not a
problem as long as one doesn't get singled out, starved>
Another quick question, I have no idea what sex my Oscars are, I read
that it's near to impossible to identify but if you have any tips so I
could get some sort of clue, it would be great.
<See WWM re... use the search tool, indices... Oscar Reproduction FAQs.
Re Silver Dollars chasing each-other 12/31/12
My Silver Dollars look like their fighting for territory, also they have
small bite marks on their side but
> they don't seem to be biting each-other.
> <Mmm, well they do... as you state, territoriality mostly... not a
> as long as one doesn't get singled out, starved>
> Another quick question, I have no idea what sex my Oscars are, I read
> it's near to impossible to identify but if you have any tips so I
> some sort of clue, it would be great.
> Thank you
> <See WWM re... use the search tool, indices... Oscar Reproduction
I Searched but nothing. I still have a problem with Silver
<<See prev. corr.... B>>
Will different silver dollar species school
Hi Crew - I have 4 spotted Metynnis (spotted silver dollars) and wanted
to add a couple of normal silver dollars to add variety. Will they
<They'll get along, but there's no guarantee they'll
school together. A good rule of thumb is to keep no fewer than five of
any one Silver Dollar species. Any fewer and there's always a risk
of in-fighting and dominance issues. Of course, your own mileage may
vary, and the size of the tank makes a huge difference. Cheers,
Molly & Dollar... beh., sys.
I have quite a strange situation going on and I'm honestly
not too sure how to go about fixing it.
<Do start by reading here:
Mollies are very misunderstood, and a depressing proportion of
them end up dead prematurely.>
Recently, my boyfriend and I purchased a balloon molly as well as
a silver dollar. Just the other day we also purchased a 29 gallon
tank, so in a week or so we will be getting a few more of each..
the thing is, our molly seems to adore the dollar. Whether or not
it's a sign of aggression, I'm honestly not sure.
<It is aggression. I've seen this same thing before with
Sailfin Mollies and Australian Rainbowfish.>
Basically what is happening is that our molly is always stuck
right next to our dollar. Usually that's all he does, he just
sits next to the dollar, occasionally he may kind of rub up
against the dollars side.. sometimes though the molly sort of
nips at the dollar's side and the dollar may take off
suddenly but usually slows down and the molly's right next to
his side again.. now the dollar doesn't seem to mind the
molly all that much- usually if the molly goes off to pick at
some food or whatever, the dollar is right behind him... I've
read before that sometimes mollies will nip at
other fish but not in a harmful manner. I'm not sure if this
is true but I'm just beginning to wonder how much stress this
is causing the dollar, if any at all... I have searched the web
and cannot find this same situation happening to anybody else. As
I said, in a week or so we will be moving them to a bigger
aquarium, I'm just wondering what might happen if we get a
few of each.. we were thinking of at least one other dollar,
maybe two, but reading this site, it looks as if I'll need
more...? Please tell me what you can! As I said, the molly really
doesn't seem to cause any harm at all to the dollar- he seems
to absolutely adore him.. and to be honest- the dollar
doesn't really seem to mind the molly all that much either..
I attached two photos, both of them have each fish together.. the
second one is a little tougher to find the dollar but if you look
at where the molly's lips are....... I apologize for the lack
of quality, I lost my camera so I had to use my phone to take the
pictures.. Anyway, please let me know if this is causing stress
on either fish or if it will once we purchase a few more! Thanks
so much .
<Now, there are two issues here. Firstly, Silver Dollars are
schooling fish. They need to be in groups of 5 or more specimens.
They also get very big. VERY BIG. So unless you have a 55 gallon
tank in the near future, don't keep them. These are big,
nervous, herbivorous (eats plants) fish not suited to the average
community tank. Now, as for the Molly. Male Mollies fight for
dominance by showing off. Essentially they display their size and
fins to one another, and the one with the biggest fins wins. What
happens if a male Molly is in "solitary" confinement is
that he looks for females (finds none) and looks for rival males
(finds none). Then he looks for anything that *might* be a Molly.
My guess here is that arch-backed fish -- like Australian
Rainbows and Silver Dollars -- resemble the silhouette of a male
Molly with erect fins. In other words, your Molly thinks the
Silver Dollar is another male Molly threatening him. There's
no resolution here -- the Silver Dollar can't change his
shape -- the male Molly neither beats the Silver Dollar nor gets
the Silver Dollar to back down. So the rivalry goes on and on.
The two species are not really compatible, so I don't see any
point trying to get them to live together. Mollies need very
hard, basic water, ideally slightly brackish; Silver Dollars want
middling temperature, soft, acidic water. Put each in their own
aquarium suited to their needs, and your problem goes away.
Simple as that. Cheers, Neale.>
Red Hooked Metynnis 6/8/06 I have 3
large red hooked Metynnis. The old guy or girl has been with
me about 20 years. <How nice! Myleus are faves of mine> I feed
them a diet of green beans, bananas, lettuce and Hikari
Cichlid Gold medium pellets. I know this is a long time for
a fish to live but just how long have these type of fish been known to
live. If you have time please give a response to me
question. Thanks so much Jean Smith <I do
believe there are some western European public aquariums that have had
this species for more than thirty years. Bob Fenner>
Re: Red Hooked Metynnis 6/9/06 Thanks
so much for your reply. I have mine in a 55 gal
tank. As I said I have the old one, and one that is about l0
years old and a juvenile that I have had about 5 years. The
old ones hook has lost some of the red and it seems to me that his red
color has faded some. I keep hoping that they might spawn.
<Would likely need more room...> Also I have two small ones that
I bought last year. They do have big teeth The
two older ones have brown and black markings on them but the young one
is still silver. They are kind of crazy sometimes running
into the tank and hurting their noses. <Mmm, again... need bigger
quarters> I just love them! Again thanks for
your reply. Jean <Thank you for sharing. Bob
hi. <Hello!> my oldest silver dollar has gone
mad! - 6/7/07 <Oh dear.> he swims frantically around our tank
& has hurt himself badly <Odd. Usually, this means the fish is
unhappy for some reason. Can be water quality, but other factors to
consider are: Noises (such as loud TVs or doors banging). Aggressive
tankmates. Fin-nippers.> he has taken off his lips & fore head
<Not sure what you mean by this. Is he damaged? If so, treat with
anti-Finrot/anti-fungus medication to stop things becoming septic.>
he does it at least twice a day <Try and establish if there is a
routine. Are there children banging around the house when this happens?
Characins are very sensitive to vibrations and sound. These are open
water fish, and their response to alarm is to swim rapidly away from
danger. In the confines of an aquarium, this can cause problems.>
what's wrong with him? <No idea. Does he have friends of his own
species? Silver dollars are very sociable, and won't really settled
down if kept alone. A group of 6 or more is best.> our tank is huge
& all checks are fine <Define "huge". At the very
least, check there is plenty of swimming space and strong water
current.> what do we do? <Not sure. How many silver dollars? What
are the tankmates? How big is the aquarium?> thanks Donna
Re: silver dollar has gone mad! - 6/7/07 We have 3 silver dollars.
His original friends died of old age. His new friends are only about 6
months old (had them about 3) but this behavior is new only about 2
weeks that he been acting weird, he took to the new babies straight
away & hangs around with them all the time. <Very good.> Our
tank is a huge corner one & we have a few female guppies &
black & red shark & 2 Plecs. They have all lived happy for
ages. The Water is clean, with filter & pump. He is about 7-9 years
old & I have noticed him 'jump' before when I turned the
Hoover on but in the past 2 weeks he has started dashing around our
tank for no reason, he has hurt himself now. <Very odd indeed.
He's a fair age though, so you've obviously been looking after
him pretty well.> all the skin is missing from his lips &
forehead. we are worried now & we don't know whether it is
better to put him out of his misery. he's like one of the family
though, we've had him years. <If he's otherwise fine,
schooling with his pals and eating properly, then I personally
wouldn't destroy him. I'd treat the tank with
anti-Finrot/anti-fungus so that his skin heals properly. You could also
add some Melafix as well. Give things a few weeks to see if he settles
down. You might want to remove anything rough and spiky in the
aquarium, just to make sure he can't damage himself further. You
could also add some cheap floating plants, such as hornwort or Canadian
pondweed, to see if the extra shade helps him settle down. A lot of
fish enjoy floating plants. If things still don't improve in 3-4
weeks, then maybe then you might need to destroy him.> please help
us <Cheers, Neale>