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Arowana and Silver dollars in a big planted
tank, sys. 2/29/08 Hi, I have a question that has many
different angles to be looked at. I have been reading your
website for the past 2 or 3 years and have scoured about 50% of
the freshwater info as I have found it invaluable. First off, I
have a pretty big L shaped aquarium, 8 ft long, 45 degree angle
of 4 feet, then another 45 degree angle of 8 feet with the tank
being 2 feet deep and 2.5 feet tall acrylic tank (about 900
gallons +/- 50 from evaporation etc.). Ammonia and nitrites are
of course zero, nitrates are between 20 and 40ppm (attributed to
nitrate factory type trickle Bioball sump), pH at a steady 6.8
attributed to the large pieces of driftwood I have in their and
their tannin releasing ways, hardness is at 80ppm. Temperature
ranges from 74 to 76F in the mid to upper levels, 72-75F in the
lower levels, due to lighting I guess. Filtration turns the tank
over about 5-6 times an hour, though with cloggy filters, maybe
only 3 times an hour. <Does sound like you need to upgrade the
filtration a bit; in all honesty jumbo fish need all the turnover
you can get. I'd be looking at 6x turnover minimum, and
likely 8-10. If water quality is basically sound, you can perhaps
get away with just adding a powerhead or two into the tank to
keep the circulation of the water even.> It currently houses a
foot long silver Arowana and a school of 11 silver dollars (the
smaller 5-6" ones, not the red hooks). I also have 4 fairly
young (only 1 foot tall, about 20 leaves) Amazon swords planted
in 2 inches of gravel, and a whole bunch of Anacharis that's
growing like a weed (for the silver dollars munching pleasures)
though it is growing much faster than the fish are eating them.
<Sounds great!> I also have some powerful full spectrum
lighting across the two 8 foot lengths of the tank, nothing in
the middle of the L. My more concerning question, or more likely,
situation, is that my Arowana (I've had it since it was
around 5") recently started taking dives at my silver
dollars as they swim on their merry way beneath him. Is this a
show of territoriality or is he trying to eat the silver dollars
or both? <Either. Both. Arowanas are territorial and object to
anything in "their" zone of operations. This varies
with species, and Silver Arowanas are very much at the mild end
compared with, say, Scleropages jardinei. But on the other hand
that doesn't make them friendly community fish! If the
Arowana is sufficiently big, it may be trying to eat them, or at
least "sample" them to see if they're edible. A
6" Silver Dollar is borderline when it comes to safety with
an adult Arowana. Some people have mixed them fine, I know; but
look at how big the mouth of an Arowana can get! I wouldn't
be 100% comfortable with this combo.> The silver dollars are
way faster than him though so I have not yet scene what happens
when he catches them. He is usually just silently sitting beneath
a carpet of Anacharis during the day and only moves when fed
(Hikari Arowana pellets plus weekly beef heart, plus whatever
flakes, crumbles, bloodworms I feed the silver dollars) or when
the lights are off. Also, I read that Arowanas generally
leisurely patrol the aquarium all day and I figured now that I
finally built my uber aquarium (oh that's right, self made...
20% of the retailers price... plus several cases of beer and
pizza for friends who assisted in heavy lifting. <Ha!> Is
it possible that my lights are too bright and the Arowana
doesn't feel safe or its hurting his eyes, though he did just
swim around normally for about a month until he started to
"hide"? They are power compact fluorescents, 525 watts
per light fixture, 4 total fixtures. This is a major concern to
me as I have been keeping fish for the better part of a decade
wanting an Arowana but refusing to get one until I could house it
properly and now he just sits there. At night I have moonlighting
and he does then move around quite a bit, this is why I suspect
the lighting, but I never thought they were nocturnal... more
diurnal from what I read. <Difficult to say on this one.
Arowanas are noted for being photophobic, though most fish prefer
shade to bright light. Do all the lights come on at the same
time? Sometimes fish get alarmed by that, and having the lights
come on across an hour makes a big difference. It does sound like
he doesn't like the light. Is adding an understory of plastic
plants (there are some great 3' plastic plants available now)
an option? Something that could drape across the surface and cast
some more shade? I suppose the experiment would be to unplug one
light fixture for a day or two, and see if the Arowana prefers
that end of the tank.> My next question has to do with the
silver dollars and them seeming to enjoy eating the Amazon swords
more so than the Anacharis. Is there some other large show plant
that does well under high lighting that the silver dollars wont
want to eat? <I'd perhaps look at Crinum spp., e.g., C.
calamistratum, as these do seem to be left alone by herbivores.
They're big and generally hardy. Java fern will do great
under bright light, though it does tend to become an algae
magnet. Anubias even more so.> Also, my swords aren't
exactly growing as well as they had in past tanks with 4-5 inches
of gravel. Does the gravel depth make that much of a difference?
<Yes; also the quality/composition of the substrate.> I
have something like a thousand Malaysian trumpet snails aerating
the gravel and what not but am concerned that if I add more, the
snails just wont be able to irrigate and aerate all that gravel,
and the last thing I want is some anaerobic environment
unreachable by plant roots or snail burrowing releasing poisonous
hydrogen sulfide and the likes into my tank, plus stinking up my
fish room. <Just doesn't happen. The "anaerobic
decay" thing is largely a myth. Happens naturally in ponds
and in marine tanks (inside living rock) and no-one fusses. So by
all means ramp up the depth of substrate to what worked before.
Do also check first that the substrate is adequate though --
Amazon swords want a nice rich soil or Laterite enriched
substrate, and plain washed gravel just won't work for
them.> Should I consider ditching the silver dollars for a
school of tinfoil barbs? They don't eat plants at all do
they? <Tinfoil Barbs can, will eat plants.> And lastly, as
you may have guessed it, I want to add more fish to this tank as
it seems fairly empty... I'm thinking black ghost knife?
<In theory fine, but you'll be hard pressed finding an
adult large enough for this community. Mostly you only see baby
Apteronotus for sale.> I first filled up the tank about 8
months ago, filling it with something like 100 Malaysian trumpet
snails and about 20 mystery snails for my tank cycling. I over
fed the snails for 3 months in order to obtain the current
population explosion of snails I now have, <Consider adding a
group of Clown Loaches or thorny catfishes (Doradidae). These
will eat the snails, if sufficiently hungry.> at the end of
month one I added the sword plants, then I added the silver
dollars at the end of month 3, all at about the size of, well,
silver dollars. They mostly hid in the center decor castles of my
tank for the first two weeks but then began to sprint (if you
will) from one end of the tank to the center and back (they
seemed to never travel into the leftward portion). After having
them in there for 2 months, they had grown to about 3" in
diameter each and I added my Arowana at 5". After only
another 3 months the Arowana (from what I could tell) doubled in
size, which I attributed to it having so much space to swim.
<Or simply good maintenance. Arowanas grow quickly if kept
well.> Now I added the Anacharis about 2 weeks after the
Arowana was added and it was generally ignored by all but a
couple of snails. Then a month ago (beginning of month 7) is when
the Arowana began to just sit under the Anacharis. So yeah, back
to the black ghost knife... I want to buy two of these guys (I
figure the tanks big enough) and I put two PVC condos with 15
pipes of 2" diameter and 1' length in there, one in each
8' portion. Should I be concerned about the Arowana eating
them as I often find the knife fish around 4-5 inches in length
max, and it will be some time before they grow to their 2'
potential where the Arowana wont (hopefully) eat them. Are the
black ghosts fast enough to evade the Arowana if pursued? <No;
sooner or later, if they're small enough to swallow,
they'll be eaten. The Arowana only has to get lucky once!>
And for the record, despite clown knives growing huge and not
being swallowable by my Arowana, they will probably eat my silver
dollars and knock over my plants, and just grow too big for my
taste, so that options out. <I agree.> Well, that's all
for now. I literally read all over the web for months and
abstained from just writing you guys since I know how annoying it
can be to be asked simple questions that have their answers
everywhere... but I just cannot find anything like this Arowana
diving at silver dollars thing while not swimming anywhere else.
I am a student of the sciences, my job being that of a
biochemist, therefore I was cocky, stubborn, and reluctant to ask
for help (a character flaw repeatedly pointed out by many over
the years)... but there are just some things you cannot learn in
books. I'll likely have another question or comment in a
couple of months after the knife fish are added... if they are
compatible. Thanks in advance for any advice you can provide.
With Best Regards, Matt <Hope this helps, Neale.>
Re: Arowana and Silver dollars in a big planted tank (RMF,
please comment) 2/29/08 Well It looks like
I'm going to be upgrading my sump pumps using some pond pumps
to get that water flowing up to the 10 times over level. I
currently have four overflow filters going into four 55 gallon
tanks... I guess I will just have 4 extra pumps to sell on
aquabid.com as I replace them with the pond pumps. The pumps I
have looked at are reporting 1800 gallons an hour (Danner Supreme
Mag Drive Aquatic pumps, I currently own the 1200 gph pumps)...
am I going to need larger sumps or will this push through the 55
gallon tanks just fine? <No idea; RMF, any
thoughts?><<I would definitely be reading, making
careful choices here... There is much to be saved in the way of
electrical cost, pump noise, waste heat, service life, by making
good decisions re pumps... The Sequence series/Baldor motored
lines are some faves for the size, application here. Other
fractional horsepower pumps are ably reviewed here on WWM:
http://wetwebmedia.com/pumpselmar.htm and the linked
files above. RMF>> This company also sells a 5000,
specifically designed for large ponds and waterfall displays
which reports 5000 an hour. Is that overkill or should I add one
or two of those in too? I guess two 1800 and two 5000 gives me
13600 gallons an hour claiming about 15 times an hour for the
whole tank... realistically maybe 11-12 times an hour turnover?
<Probably overkill. 8-10 times turnover should be
adequate.> As for the silver dollars not being fully
compatible, I will look into giving them a new home. I have just
been keeping silver dollars for 7 years now and figured I was
pretty good at it. My last batch of 7 didn't die, with the
oldest being 5 years old starting in a 55 gallon and moving up to
a 120 gallon for the remainder. I just gave them to the LFS
before I moved halfway across the country for the job that would
allow me to have such a lavish aquarium. What other fish come to
mind, that would be an attractive school of 15-20, that could be
raised in one 8 foot section (separated by a divider) until large
enough to not be eaten by the Arowana? I'm thinking Bala
sharks? <A good choice. But also Semaprochilodus taeniourus
look amazing in large groups, and are nice Amazonian fish.> I
read they get to 12-15" and from my limited experience, are
very fast. <Oh yes.> Do they eat plants because I cannot
find info saying that they do, but then again, I was wrong about
the tinfoil barbs. <Balantiocheilos melanopterus generally
ignores plants. It eats green algae and invertebrates, and may
nibble on tender shoots, but that's about it.> Maybe 6
months separated, grown to 7-8 inches then set to survive with
the Arowana? <You may also be able to get adults via Fish
Forums, fish clubs, etc. Lots of people buy them, and then have
to rehome them when they get too big.> Are their any other
fish you could recommend as I have limited experience with large
schooling fish. <There are a lot of nice big barbs. Severums
would also look quite nice, and occupy the midwater. They're
territorial when spawning, but your tank is big enough that
shouldn't be a problem. What about catfish? Sorubim lima is a
nice big (45 cm/18") schooling catfish. It's very
peaceful, pretty, and quite easy to obtain. It famously likes to
swim vertically leaning against plants and rocks, so is
definitely fun.> As for the lighting, the timer IS set to go
on all at once come 10am and turn off at 8pm. Some sunlight does
come through the one window and glass door to wake the fish up,
but I guess that is nothing compared to a full 2000+ watts
blazing into their eyes all at once. I can turn on the actinics
at 10 am, then 2 of the other full spectrums on at 11, and the
rest at 12... and then shut them off in the same manner (off to
Home depot again for more electric timers). I assume this will
still be ample light for the Anacharis and Amazon swords.
<Should be. Try it, and see what happens!> And I do have
two 3 foot plastic plants draping across the top of my tank which
cover an area of maybe 4-5 square feet each. They are located in
between the Amazon swords as to not rob them of light. I
don't really want to put much more over the plants, but there
are still many other places in the tank to add another 4 to 5 of
those 3 footers without disrupting light to the live plants. I
will give them a try since they are cheap and fairly realistic
looking. As for the other plants, I do have an Anubias growing on
a piece of driftwood, though the plant is 3 years old, started as
3 leaves, has maybe 30 now, and has only moved about 1 foot
across the driftwood (3 foot long driftwood). It used to be house
with a Pleco so perhaps his constant sucking of the driftwood
would constantly cull the Anubias... or maybe the thick film of
algae growing on its leaves is inhibiting it? <I've tried
Anubias with my Panaque, and it gets turned into a Swiss Cheese
Plant, so I agree with you here!> Ill try out the C.
calamistratum when I find it. If nothing else the LFS can order
it for me. <Mail order plant distributors abound, and this is
a fairly common species, at least here in the UK.> I do have a
Sailfin Pleco in there too. He's only about 8 inches long
though so he is having a problems stopping all the algae as of
yet, though I have faith in him (or her, I cant tell yet).
<Once they mature they aren't really algae eaters, so
don't hold too much store by this. Plecs generally are
omnivores, and algae is only a part of their diet.> As for my
substrate, it is just painted black artificial gravel. I add
trace minerals for the plants, but I guess that's just not
gonna cut it. <Indeed.> It will take some time to clean all
200+ lbs of gravel out, but I would say in half a years time I
should have 4 inches of Laterite enriched substrate in there.
<Can't begin to tell you how much I sympathise! Anyone who
has grown aquarium plants (or tried, at least) will have been
through the mill of changing substrates.> I guess I wont be
getting the black ghost knife anytime soon, if ever, aw well.
<Again, look out for "second hand" specimens.>
Maybe I'll get some water in my 120 and raise him in there
until he's big enough for the show tank. <Quite.> And
perhaps I misspoke about the snails as a pest, as I want them in
their. I have never been able to keep a tank as clean as I do
when I have snails in their. <I wonder if Apple Snails would
help on the algae front?> I once had a tank with 4 yoyo
Loaches in there that cleaned out the snail population, there was
a gradual decline in water quality, and an increase in detritus
and algae that I fought for a year... I removed the loaches to
the LFS and my tank recovered to crystal clarity in 3 months
time. <Not impossible.> Therefore, largely based on this
single experience ( I know, that's poor scientific form) I
like to always have snails. And despite the appearance of (now
about 100 mystery snails) snails crawling all over my tank with
about 1 snail on every 4 square feet of glass (or I guess
acrylic), I find it more peaceful and artful than an eyesore.
<Indeed.> It looks to me as though your experience in the
trade has done it again. Thank you very much for your assistance.
Matt <Good luck, Neale.>
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