FAQs on Jack
Related Articles: Jack Dempseys, Oscars, Neotropical Cichlids, African Cichlids, Dwarf South American Cichlids, Cichlid Fishes in General,
Related FAQs: Jack
Dempseys 1, Jack Dempseys 2,
& FAQs on: Jack Dempseys
Identification, Jack Dempseys
Behavior, Jack Dempseys
Selection, Jack Dempseys
Systems, Jack Dempseys Feeding,
Jack Dempseys Disease, Jack Dempseys Reproduction, &
Oscars 2, Neotropical Cichlids 1, Cichlids of the World, Cichlid Systems, Cichlid Identification, Cichlid Behavior, Cichlid Compatibility, Cichlid Selection, Cichlid Feeding, Cichlid Disease, Cichlid Reproduction,
20 Gal Long Juve JD Cichlid-any other ok?
I am really wanting to put at least two more fish in my 20 gal long tank (I
think its 29, but the BF thinks its 20).
<What are the dimensions? In the US, the standard 'long' 20-gallon tank measures
30 x 13 x 13 inches. The standard 29-gallon tank is 30 x 12 x 18 inches, so much
deeper though similar in length. A typical ruler measures 12 inches/30 cm, so
stick one of those next to the tank. If the tank height is similar to the ruler,
it's a 20 gallon tank; if the tank is 50% taller than the length of the ruler,
then it's the 29 gallon tank.>
I have about a 2 inch JD who is very aggressive.
<Not uncommon. This species is unpredictable; often fairly tolerant given space,
but some are, indeed, extremely nasty. Hard to imagine a 2-inch specimen killing
an adult (45 cm/18 inch) catfish though, unless it was armed with a chainsaw. Do
check for other reasons the Plec might have died; not unknown for a fish to be
described as killing another fish when it was merely scavenging on the corpse.>
He killed the plecostomus and another fish I left in with him (maaaaaaybe on
purpose-an aggressive baby molly eating zebra Danio) he ripped its belly right
I would love to add a couple other fish for variety into the environment.
<All sorts of options, but all made of plastic, sadly.>
I just set it up yesterday and put him in there last night. Would I still need
to rearrange the rocks? And what would be compatible? I wanted a Firemouth, but
I read on your site they are too delicate.
<Far too delicate. Their jaws become dislocated in any sort if fight, and the
Firemouth starves to death across the next few weeks. Horrible way to go, and no
Is this tank too small to house multiple juvenile cichlids? I am pretty sure
mine is a male as there is a red stripe along its dorsal fin.
<This species is actually pretty difficult to sex, and both sexes can have
colours on their fins, or none! Certainly a two-inch specimen will be impossible
to sex reliably.>
Thank you very much!
<Ashley, I do fear this is a non-runner. You have a nasty fish here, and likely
will need to be kept alone. In much bigger tanks (55+ gallons) it's certainly
possible to keep JDs alongside robust catfish of similar or larger size, but
your tank is just too small for that to work. Indeed, 20 gallons isn't really
viable long term for a fish that should get to 6-8 inches/15-20 cm. Like Jewel
Cichlids, there's a reason Jack Dempseys are ignored by most hobbyists despite
being extremely pretty -- aggression.
Silver dollar and E. Blue Jack Dempsey? Comp.?
First off, I love your site. It's an invaluable tool for any fish
Most of what I've learned over the years has either come from here or
been reinforced by your site, especially as it pertains to reef tanks.
I've read about all I can here regarding my freshwater question and
can't quite find a definitive answer.
<Let's see if I can help>
Right now I have a 29 gallon with 2 small black moors and about a 4-5
inch silver dollar that I rescued from a bad situation. I know this
arrangement is hardly ideal, but everyone gets along. It has an AC70
fully loaded and another smaller power filter with some floss just for
It's heated to around 78 for the silver dollar's benefit and the
goldfish don't mind.
<Agreed. Fancy goldfish are fine at this temp.>
NH3 is zero, NO2- is zero and NO-3 never surpasses 40
<I'd keep under 20 ppm>
or so with water changes. Everybody is happy for now. But I've always
known the arrangement wouldn't be permanent.
So I purchased a used 46 gallon bowfront in hopes of setting up a tank
for the silver dollar with more of his kind and other proper tank mates.
The problem is that of course the tank came with what I'm pretty sure is
about a 5 or 6 inch electric blue Jack Dempsey. I have him in a holding
tank until I get the tank set up properly.
Is there any chance of these two fish living peacefully together?
<Mmm, maybe... w/ enough room to maneuver... and the Dollar being
introduced first... a few days to become familiar... they might get
along. I give the situation about a 50:50 chance>
Or is the cichlid going to have to go with other cichlids only?
<Mmm, maybe not even this/these>
I don't want to take much of a chance with the dollar's well being. I've
already nursed him back from bad shape once. The dollar is very
submissive, presumably from sharing space with the boisterous yet
well-intentioned moors. The Dempsey also seems rather unagressive, at
least to the extent that I've observed him thus far. He had shared his
tank with an Oscar until it died when the owners moved. He spends all of
his time under his little tree-cave. I suppose all of this previous
behavior can go out the window when certain species are mixed.
<And certain individuals>
I suppose another option is to simply rehome the Dempsey to someone that
knows what they're doing. I've always wanted a cichlid tank but I really
hate to have to build around one fish and not have options about tank
mates. I always pictured my cichlid tank with Mbunas.
What do you think my options are? What would you do?
<Maybe try mixing the two... with a plan to trade one or the other in...
longer term, another tank/system>
I patiently await your sage response.
<Sage as in the herb I take it. Cheers! Bob Fenner>
Ornate Bichir and Jack Dempsey (comp.
Love your site. So on to my problem. I have a Dempsey who's now
approx 5yrs old and quite large along with a Ornate bichir who is
approx 3 yrs old and about 12inches long. They have never had problems
in the past but I'm now finding that the bichir is nipping at the
Dempsey at night. I never would have imagined that I'm fearing for
my Dempsey's well being but i am. Is this a sign of future more
<Could well be>
should i separate them now?
<Yes I would>
Oh and i have this going on in a 60 gallon tank. I'd hate to part
with either one. :( . Your thoughts?
<Another system! Cheers, Bob Fenner>
mates for Large Electric Blue Dempsey
Tankmate Choices For An Electric Blue Jack Dempsey 9/24/11
Hello, I have been a follower of your website for sometime and
information on it is of highest quality and usefulness!
< Thank you for your kind words.>
Story/question is as follows:
After growing out several Electric Blue Jack Dempsey cichlids I am left
with one (lost some, sold others - fragile little beasts!) - an almost
4-inch large healthy male (pointy dorsal fin with red fringe).
His tankmates in a 55-gallon tank include:
7.5-8-inch Senegalus Bichir
4-inch Senegalus Bichir Albino
2.5-inch 2-year old perpetually cranky convict female that had via
biting, spawning 2-3 clutches of eggs at a same time in various parts
of tank, more chasing and biting - stressed out her much larger male
into being sick. Male had been taken into a different tank, but she
still can and does stand for herself.
Panaque of smaller species (brown with yellow-golden lines across
bought to replace Plecostomus of large size and nasty bichir-harassing
7 female Congo Tetras (about 1-1.5 inch each)
Being larger of 2 remaining cichlids, Jack started picking fights with
Convict. She wins every one so far. Partially because ritual of
shaking-to puffing up-to locking jaws-to potentially fighting is lost
on her, - she
simply bites Dempsey on the nose or fin as soon as he comes too close.
He usually comes back in few minutes and puffs up and opens mouth at
her again - and gets bitten on the nose as soon as she sees what
possibly she can only consider as a nonsensical showing off by this big
shiny rude boy!, - but given size difference and that fact that Jack is
still growing, I'm afraid this situation will not stay such for
Either he will kill the Convict or she will injure or stress out
Congo tetras were purchased to be dither for EBJDs while growing out,
but none of EBJDs paid any attention to them. I would not count on them
diffusing Jack vs. Convict aggression.
I am looking to introduce more cichlids to help drive aggression
1 or 2 convict females;
1-2 Rainbow cichlid;
Salvini? (gets large, but I had kept one that was very peaceful
I do not seek a large cichlid because EBJD is still a man-made fish
with fragile health and compromised ability to withstand competition
for territory. A short introduction attempt of a regular Dempsey
juvenile) ended on a second day with my guy gasping in the upper corner
- and juv running the tank (he was then exchanged back to store)
Non-cichlid species suggestion would also be very very welcome - given
that they should be large enough to avoid looking tasty to Bichirs.
Thank you so much for any recommendation you can give.
(filtration in tank is good - Eheim rated for 120 gallons, gently
cleaned once a 6-8 weeks at least and an aerator, temperature at 80-82
F, ammonia and Ns at 0, water unfortunately is a bit soft but I'm
hoping to try mix of baking soda, Epsom salt and marine salt to bring
it up, or adding crushed limestone to filter media) Elena E.
< You are correct that this line bred cichlid is more fragile than
its normal cousin.. If you drop the water temp to 75 F it may take the
female convict out of breeding mode. Pick a female rainbow and a female
salvini as tankmates. The cooler water will keep them from wanting to
breed and they will not get as big as the males to threaten the
Jack Dempsey 9/5/11
I have a jack Dempsey that is about 6in long and about 1yr old. I moved
him from a 55 gallon into a 125 gallon tank and was wondering what
other fish I can put in there with him. I only have 2 catfish in there
with him at the moment. Thanks in advance.
<Rocio octofasciata is not a community species for two reasons.
Firstly, it's very territorial, and secondly, it's
opportunistically predatory. The best companions are larger, equally
robust Central American cichlids.
Firemouths are too weak and their delicate jaws are easily damaged
(that's why Firemouths rely on bluff), but the more aggressive
things like Convicts, Salvini, Texas cichlids, Midas cichlids, and
will generally do well, assuming the tank is of reasonable size. Now,
your problem here is that your JD will consider 125 gallons its
territory, and males especially are notoriously aggressive. If you just
add a bunch of new cichlids, there's a good chance you'll end
up with a bloodbath! Choose cichlids of equal or large size to the JD,
and remove the JD before you add them, rearrange all the rocks, and
after the other fish have settled down (say, an hour or two later),
return the JD *with the lights out for the rest of the day!* No
guarantees, but with luck, your JD will accept the tank as a new
environment and the new cichlids as part of the scenery. Cheers,
Jack Dempsey, comp.
I have a Jack Dempsey that is about 6in and a I just moved him from a
55 gal into a 125 gal and was wondering what other type of fish I could
put in the tank with him. I currently have a blue catfish
<Ictalurus furcatus? You do understand these are MONSTER catfish!
Even under aquarium conditions you can expect 2-3 ft, and in the wild
they're much, MUCH bigger. Your poor cichlid will be food.
Obviously Ictalurus furcatus needs an aquarium much larger than the 125
gallon tank, 8-10 times
in the tank with him. Thanks in advance.
<JDs will cohabit with a variety of Central American species. Avoid
Firemouths (they're too easily bullied) but Convicts, Jaguars,
Midas, Red Devils, etc. all work well. Green Terrors from South America
work well, too. Wouldn't personally keep them with Rift Valley
cichlids, though I dare say some of the robust rather than aggressive
Mbuna could work, e.g., Yellow Labs. Basically choose semi-aggressive
fish in the 6-10 inch size range sharing the same need for hard,
alkaline water. Large adult Plecs can work too. Rocks and bogwood will
be required to break up territories and to provide hiding places.
Jack Dempsey and Oscar in 60 gal
Hi! First off, great website! Lots of useful information.
<Thanks for the kind words.>
Anyway, I recently bought a JD, an Oscar, a convict and a green terror
for my 60 gal tank. They were all of the same size.
<"Were" being the key word. These cichlids all have very
distinct requirements and adult sizes. While Oscars and to a lesser
degree Green Terrors are soft water fish, Convicts and JDs need hard,
alkaline water, so you shouldn't be keeping them in the same tank
anyway. On top of that, Oscars are fairly mild, Convicts territorial
and aggressive but limited in size, Green Terrors potentially pretty
nasty but compatible with Convicts and JDs, and JDs generally not too
nasty until sexually mature but can be extremely aggressive. What you
have appears to be a random collection of cichlids rather than species
chosen because they will get along. Do, please, read one of the many
excellent books on cichlid aquaria.>
Everybody seems to get along except for my JD who keeps bullying my
What can I do?
<Not much. Your tank is too small for a random cichlid collection. A
tank divider will work in the short term, but unless you have 150+
gallons, I wouldn't put much money on this bunch of rogues getting
Sent from my iPhone
<Sent from my computer. Cheers, Neale.>
Re: Jack Dempsey and Oscar in 60 gal tank
Any books you could recommend that would say which cichlids can live
<Hmm'¦ well, 'The Cichlid Aquarium' by Paul
Loiselle is perhaps the benchmark, but it's a text for advanced
aquarists willing to read scientific as well as aquaristic information.
It doesn't necessarily say which species would work in a given
tank, but instead provides you with the knowledge you need to make
predictions. 'Pocket Professional Guide to Cichlids' by David
Boruchowitz is easier to read and more "American" in tone
(there's a marked contrast between German aquarium books and
American aquarium books when it comes to style and content). It's
well regarded and a fine alternative to the Loiselle book. Once you
start concentrating on cichlids from particular areas, then you
probably want to hunt down books by authors known for their expertise
in those areas, for example anything on Malawian cichlids by Ad Konings
is likely to be well worth reading.>
Sent from my iPhone
<Really? Won't Steve Jobs be pleased! Cheers,
please help 6/20/11
Hello, I have a 55 gallon fresh water fish tank. It contains
one Jack Dempsey, one African Cichlid,
<What sort? Some sort of Pseudotropheus zebra hybrid? Will be rather
aggressive, and does need a much different (i.e., plant-based) diet
compared to the largely carnivorous (e.g., insect larvae, crustaceans)
preferred by Rocio octofasciata.>
and my pride and joy an electric blue Jack Dempsey.
The electric is about three inches long where the other two fish are
between 2-2.5 inches. I woke up this morning to find that front part of
my electrics face had turned black and lost its shiny blue
What have I done wrong?
<Can't tell from your data, but could well be stress caused by
behavioural problems. Two male Rocio *will not* cohabit in 55
These fish are prone to be very aggressive, but they have lived in
harmony for over six months now.
<They're sexually mature now, and likely physically stronger,
I have already tested the water today and all the levels came back
<Meaning what? What is the hardness? The pH? The nitrite level? The
I just do not want to cause any more harm to the my electric.
<Review aquarium conditions, review the needs of these two species,
and act accordingly. This is very likely a social or environmental
problem you've caused, so easily fixed by making the appropriate
changes. Cheers, Neale.>
Jack Dempsey Eating Tankmates
Hey my names Nate I've read a few questions/answers on y'alls
site and you seem very knowledgeable about fish. I've got a 75
gallon tank with a 8 inch Jack Dempsey, blood parrot, and parakeet eel.
All the fish are fine with the Jack except for three algae eaters I got
a couple days ago. They were all about 1.5 inches long and notice I can
find one. I'm think the Jack may have ate them is that possible
GSent from my iPhone
< It is either the Jack Dempsey or the eel. Both are capable of
eating smaller fish.-Chuck
my jack Dempsey 6/21/10
I'm only 15 but I have a great interest in fish.
I currently own about a 4 or 5 inch Jack Dempsey and I have a couple
questions I was wondering if you could help me with.
First of all is it better to put a jack Dempsey in with another jack
Dempsey while he's still young
<You can rear juveniles together this way, but there's no
guarantees at all they'll stay "friends" once they
mature. Indeed, at this size your fish may be sexually mature already,
in which case adding another fish could (will) cause problems. Male JDs
are very aggressive, both to one another and females that won't
mate with them. Although pretty fish, JDs have to purchased with the
knowledge they will probably be kept alone. They aren't community
fish are mix with relatively few fish. Creating pairs using two adults
assumes [a] you can sex them, which is difficult; and [b] you can use
some egg crate or similar as a divider while introducing the fish and
have the potential to rehome one or other fish if the pairing
doesn't work, which it probably won't.>
and small or would I have better luck with an Oscar around the same
<How big is this aquarium? Oscars need at least 55 gallons, and
realistically 75 gallons to be kept successfully. In smaller or more
overcrowded tanks they are prone to diseases like Hole-in-the-Head.
Unless this aquarium was above 100 gallons, keeping an Oscar and a JD
would be a bad idea.>
Even though I would prefer to have 2 Jack Dempseys
<Unfortunately, these aren't fish that work this way. You can
prefer all you want, but isn't going to happen! JDs are either kept
singly, or in mated pairs, or in VERY LARGE tanks alongside other
Central American cichlids.>
I would like to know witch one would get along better and not bring
harm to the other.
<In big aquarium, 100 gallons upwards, Oscars can be kept with all
kinds of other soft water fish. Plecs, for example, or Clown
Also right now I only have a 10 gallon tank,
<For a JD! This isn't going to work! These fish reach 20 cm/8
inches within a year. There is NO WAY you can keep two specimens in a
tank this small without death and destruction!>
I have heard a 55 gal is good for one but how large should the tank be
for 2 will a 100gal work?
<If they're a pair, yes, 100 gallons is fine, and you could keep
them with appropriate midwater dither fish. I think you need to read
'The Pocket Professional Guide to Cichlids' by David E.
Boruchowitz before you do anything else, and ideally 'The Cichlid
Aquarium' by Paul Loiselle as well.>
and lastly I have heard Jack Dempseys like sand bottoms and not very
many plants but lots of rocks is this true?
<They like plants plenty. But they also uproot them while spawning.
Floating plants (e.g., Indian fern) and plants attached to bogwood
(e.g., Java fern) work fine. JDs like to dig, so yes, sand is
appreciated. But it isn't critical.>
thank you, From J.G.D
Terrible man buys Jack Dempsey for community tank
Mixing Old World and New World Cichlids 9/30/09
Hi, all, it's been a while since I had a question to which your
wonderful site didn't already have the answer. Well, I have one for
you (sorry for the long post!!). I've recently decided to
transition my boring 150 gal (72"x18"x28") generic
community tank to a cichlid tank. I generalized 'cichlid tank',
because my original intention was to keep Africans (Mbuna, haps, and
maybe some peacocks). To this end I bought three 2" yellow Labs,
three 2" cobalt blue zebras (Metriaclima callainos) a 3.5"
'breeding pair' of red zebras (Metriaclima estherae var.
"Red"), and a 1.5' unidentified juv. Haplochromis of some
type (my daughter fell in love with it) and QT'd them for a month.
They are now in the 150 with 9 sword-tails, 6 stunted silver dollars
(1.5 yr old and only 2-3"), 4 Lg hatchet fish, 4 LG bleeding heart
tetras (easily 2-2.5"), 5 serpae tetras, 5 Lg diamond tetras, one
3' run-of-the-mill Pleco (we've had really bad luck with
Plecos--lost 4 in a row during QT), two 1' Corydoras cats (spp?),
one 4.5' Synodontis eupterus, one fat 3.5' Synodontis
nigriventris, and a 3 yr old (in our tank) Boesemanni rainbow that
seemed to go blind about 4 months after we got him (eyes clouded over
but no fungus or anything and still manages to eat/survive). We
intended to stick to more community-oriented Africans....but then I
fell in love with a Firemouth pair (approximately 3 1/2") and a
jack Dempsey (approximately 4 1/2"). They are currently in a 29
gal (30 1/4" x 12 1/2" x 18 3/4") quarantine tank with a
little 2 1/2" Synodontis decorus and a bunch of snails (1 Apple, 2
Japanese trapdoor, and 7-8 small Nerites of some type for my 5 yr old
son). They've been in QT for 10 days now and show no signs of
illness/disease. I am, however, surprised by the lack of aggression
from the JD. He is very content to hang out in his small section of the
QT and is occasionally bullied by the male
Firemouth. The firemouths aren't bonded/mated (I separated the
female from her mate because he wasn't as nice looking as the other
male) and the male also harasses the female'¦who also harasses
the JD. I've kept all of these animals before, except the JD, and
I've never seen such aggression from firemouths (unless defending
eggs) or heard of such a docile JD. Water quality is good in the QT (0
NH4, 0 NO2, 0 NO3, 7.8 pH, 17dH, 80 deg F--same as 150 gal.) and there
are plenty of caves/hides for all parties. My questions are:
1) Should I interpret the JD behavior as his/her general temperament?
'¦artifact of compressed environment?
< If it is a male (Less blue on the face and more on the body), then
it may get more territorial as it gets older. A female may not be as
2) Should I be concerned about the Firemouth's aggressiveness?
< This may be a male Firemouth that will set up a territory and
chase all other fish away. Those that cannot get away may be killed if
they don't fight back.>
3) I know that at some point we'll need to clear out the sword
tails and tetras but will the eventual size of the JD cause too much of
a disparity w/ the Africans? '¦the firemouths?
< African cichlids generally don't get along well with New World
cichlids. The faster Africans are heavily scaled and have lots of sharp
teeth to damage other fish. The larger JD will not be able to compete
with the faster meaner Africans. This may not lead to death, but will
lead to damaged unattractive fish that may become ill.>
4) I've been feeding the QT group cichlid flakes, cichlid pellets,
and carnivore pellets, as well as supplemental algae for the snails.
I've only noticed the S. decorus eat when we fed the tank some
blood worms'¦but he seems to be healthy'¦very
reclusive/difficult to observe'¦should I be concerned?
<Bloodworms are not my favorite cichlid food. they can pick up
toxins from the soil they ate found in and pass them on to the fish. I
recommend using high quality pelleted foods.>
5) Is the *possible* future pairing of the firemouths likely to cause
problems in the main tank?
< Pairs of cichlids can be a problem in a community fish tank.
Initially they will guard the eggs and then the wriggling fry. But as
the fry start to become free swimming the territory will become larger
and may take over a very large area of the tank and damage the other
Thank you for your time and valuable (to me and many) advice!
< No problem-Chuck>
Oscars in same tank with electric blue jack Dempseys
We have a year old 10inch white albino Oscar and a 4 month old 7inch
black tiger Oscar in a tank with a Pleco and a Hoplo sternum cat
I have recently learned about the electric blue jack Dempseys and
absolutely love them.
<As do many. But they're no different to any other Rocio
quite big, very aggressive, highly territorial, and requires hard
rather than soft water.>
I want to know if these can live together I will be adding my baby red
Oscar when he gets larger as well.
<On the whole Rocio octofasciata will be tolerated by substantially
larger Astronotus given sufficient space; on the other hand, Astronotus
are not aggressive fish and do not like fighting, and juvenile
Astronotus will be bullied, even killed, by larger Rocio octofasciata.
So it all depends on the size of the aquarium and the relative sizes of
the fish. One thing to remember though is Astronotus prefer soft water,
while Rocio octofasciata must have hard water; so your water conditions
are a factor.>
Also what size tank do I need I know the larger the better but any
ideas on what size 120 Gal?
<For three adult Astronotus and one adult Rocio octofasciata,
you're talking about 200 gallons, minimum.>
I know its possible for these two types of fish to live together as a
friend of ours has a 400 gal tank with four Oscars, two red belly
piranhas, two pacoos and two jack Dempseys.
<Your friend is insane. Piranhas shouldn't be combined with big,
aggressive fish, and since they're either kept singly (most genera)
or in groups of 6+ specimens (all Pygocentrus, some Serrasalmus
species), keeping two makes no sense at all. Pacus (Colossoma spp.) are
far too large for home aquaria, and will eventually outgrow this
aquarium; they are also much more aggressive and predatory than people
expect, and we recently had an e-mail from someone with a Pacu that
attacked and killed an Oscar. So once these two Pacus get to full size
-- potentially 100 cm in length -- the Piranhas will very likely be
bullied or eaten, and the other fish may well be injured at some
I am guessing he got away with it because of the size of tank he had.
Any suggestions would be great thanks.
<Read, learn, think carefully before combining fish species.>
Can I put a Iridescent Shark and a Jack Dempsey
together? <<BobF's go>>
For a while... I was searching the web and found your site and it
seemed like you guys knew what you were talking about. So I wanted to
ask you a question. I have a 75 gallon tank right now and I have a 4
inch Jack Dempsey and a 6 inch Iridescent Shark, and I was wondering if
my Jack Dempsey would pick on my Iridescent Shark or if they would be
fine. (I am aware that that Iridescent Sharks get quite big and once it
grows too big for the tank I will get a larger one. I know that my Jack
will get bigger too.)
<Mmm, in this sized volume, starting these two at the sizes you
mention, I do think you won't have troubles for a while... the Jack
Dempsey will likely leave the catfish alone... and depending on your
foods, feeding, the "shark" may not grow so large as to
ingest the cichlid for a year or more. Bob Fenner>
Can I put a Iridescent Shark and a Jack Dempsey together?
<<Now Neale>> 3/28/09
I was searching the web and found your site and it seemed like you guys
knew what you were talking about.
So I wanted to ask you a question. I have a 75 gallon tank right now
and I have a 4 inch Jack Dempsey and a 6 inch Iridescent Shark, and I
was wondering if my Jack Dempsey would pick on my Iridescent Shark or
if they would be fine.
<Wouldn't be my idea of a marriage made in heaven. JDs are
territorial, and while they generally ignore open water schooling fish
too big to eat, such as barbs, anything more threatening is likely to
be eyed with suspicion. Iridescent Shark by contrast are
*schooling* fish and singletons are extremely nervous. As this fish
matures it's going to feel steadily more skittish, and it's a
sad fact most Iridescent Sharks bash their heads in at some point. You
hardly ever see any specimens reared by home aquarists that have
unmarked heads or eyes.>
(I am aware that that Iridescent Sharks get quite big and once it grows
too big for the tank I will get a larger one. I know that my Jack will
get bigger too.)
<Wild JDs will get to about 20 cm, though that's uncommon
anymore given the amount of inbreeding. So unless you have a wild fish,
15, 18 cm seems to be typical. Iridescent Sharks by contrast do get
massive. Even in aquaria they routinely top 60 cm, and 90 cm specimens
are not uncommon. Wild fish supposedly get to well over a metre.
Jack Dempsey compatibility I have 55 gal setup with two
Penguin BioWheel 350 filters that has housed an 11 inch silver tip
shark cat (aka Columbian shark I think) about 3.5 years old, a large
11-12 inch Pleco about 2 years old and a Tiger Oscar that recently had
to be euthanized due to a disease of unknown origin that did not clear
up with several medications. I have checked the water
quality to rule that out as a factor and since neither of the other two
fish showed any signs of illness, I didn't think it had to do with
that. Water quality is good and has about 1 tablespoon of
aquarium salt per 5 gal of water for the sake of the shark
cat. I went ahead and bought an infant Jack Dempsey and a
Juvenile Tiger Oscar (about 5-6 inches) yesterday after researching and
researching on the compatibility of Jacks with the shark
cat. I felt if I got a Jack at a young enough age, the shark
would be able to successfully defend his territory. So far
the Tiger Oscar has taken up the same corner with the shark which he
doesn't mind as he was actually really good buddies with his former
tank mate and the Jack is over in the other corner. Long
question short, I am now really worried the Jack may turn on the shark
eventually and seeing as I have had him so long, I would hate to see
this happen. The shark is in excellent health and likes
other fish as long as they are not small enough to fit in his
mouth! What is your opinion? Do you think all
these guys will co exist peacefully or have I made a deadly combo? <
Time will tell. Eventually your cichlids could get up to a foot long
depending on the sex and this could make things pretty crowded in the
55. All cichlids seem to be territorial to some extent so it will
be a matter of seeing if each can hold and defends its
territory against each other. The fact that they are almost the same
size will help. -Chuck>
Jack Dempsey Being Bullied By Other Tankmates 11/16/05
Hi. I have a newly established 90 gallon aquarium that is currently
housing two 4" inch green terrors, two Dempseys (one is about
2" and the other is about 2 1/2"), two small Jewels, and a 5
inch blue lobster. I'm concerned about the smaller JD. He seems to
get bullied, a lot. He never gets too eat in peace, and is afraid to go
to the surface to get pellets. I tried a sinking food, and when he sees
other fish feeding hides behind rocks. He is not afraid of the
crawfish however, and often steals the lobsters algae tablet. He looks
healthy, and has no problems swimming away from the aggressive male GT
and my other JD. The jewels where the most recent addition and they
even bully him around, even though they are half his size. Is this just
normal fish behavior? Should I be worried the runt will not survive? Do
you think he will stand his ground once he gets bigger? < Cichlids
are pretty smart and remember things pretty well. Your smaller jack
knows not to make waves or there will be hell to pay. It could be sick
but I think it is just bullied to the point were it will continue to
hide from the other aggressive fish. Don't let the smaller size of
the jewelfish fool you. They are plenty tough for their size. Just
continue to try and get food to the smaller jack as best you
Jack Dempsey vs. Arowana 9/19/06 Hello, Best site
I've come across!!! < Thanks for your kind words.> I'm a
new aquarist, so this may seem like a silly question. I have a 30g
freshwater tank with a 6 in. Jack D. that is quite interesting. I feed
him all sorts of food & he is aggressive when feeding. I really
want an Arowana, but have read how aggressive they are. I plan to start
a 150g in about 6 months. Do you think this might work? Thanks for any
info-Joe < Am afraid the Jack Dempsey may not
tolerate the Arowana and may harm him. This will be up to the
individual temperament of the Jack Dempsey.-Chuck>
Mixing Dempsey with Frontosa 3/22/07 Hello, I
am picking up an electric blue jack Dempsey today (abt 1 inch). He is
going to be in a 10 gallon tank by himself until he gets big enough. I
have a number of tanks and will move him into bigger tanks as he grows.
I was curious if I could put him with a blue Zaire frontosa that is the
same size. I understand that both fishes have aggressive behaviors but
this is only a temporary thing until the Dempsey grows since I believe
that the frontosa grows at a significantly slower rate. They are both
pretty mellow when they are this size. Would you advice against this
mix? < Water wise they have about the same requirements. The Dempsey
will be much more aggressive than the frontosa. The frontosa is an
ambush predator that waits for its prey. the Dempsey will be more
active and probably push the frontosa around.-Chuck>
Big Jack Dempsey Cichlid Wants No Tankmates -- 5/14/07
Hello, I have recently acquired a Jack Dempsey Cichlid which is almost
12 inches in length from a local pet store. I put the
Jack Dempsey into a brand new 55 gallon tank with another cichlid about
the same size at the same time. The Jack Dempsey fish would
not stop attacking the fish, I.E...chasing it around the tank and
bullying the fish. I removed the fish and tried a
few days later with another one of my cichlids a little smaller than
the previous, and he attacked that fish also. I have a few
questions since I am not too familiar with the Jack Dempsey fish what
type of fish, if any, can I put in the tank? < No fish will survive
being with a Jack Dempsey that big in a 55 gallon tank.> Do you have
any suggestions as how to introduce a fish into the tank with the Jack
Dempsey? < Nothing I can suggest will work in this small tank.> I
have read online that the Jack Dempsey needs to claim its territory,
what type of plants or decorations should I put and where in the tank
so the fish can mark its territory. < In a tank this small the
entire tank will be his territory.> Sorry for asking so many
questions, I really would like to have more than one fish in the tank
with him. Thank you for you help. Have a good
day. <Sorry, I don't think that it will be
75 gallon Jack Dempsey set up.... 7/21/07 Central American
Cichlid Compatibility Issues Hello! I have recently changed my 75
gallon from African to South American cichlids. I need help with
stocking. I currently have some full sized convicts( pink and striped),
some juvenile convicts and a full grown Jack Dempsey. I received the
convicts from a friend and was thinking about keeping one or two pair
but I am not set on that though. I would like to know what I could put
in with the Jack Dempsey and Convicts or just the Jack Dempsey. I was
thinking of a single Red Devil with a pair of Jacks and the convicts.
Do you think this would work? I know there are no guarantees:) Any help
you could give would be greatly appreciated!! < As long as the fish
are all the same size they could get along. If the fish pair up then
all bets are off. A pair can take over most of the tank while
spawning.> Also they seem shy- do dither fish help to bring them out
into the open? If so what kind do I add? < Look at some giant danios
or medium to large barbs.> Also( last time I promise!) what kind of
bottom feeder should I add with these guys? < Get a good sized
Florida strain of common Pleco. Will take care of the leftover food and
the algae.> Again Thank you- you guys are the best!!! Christie <
Thank you for your kind words.-Chuck>>
Re: 75 gallon Jack Dempsey set up.... Stocking A 75 gallon
Central American Cichlid Tank -- 9/24/07 If I stayed away from
pairs how many fish would you add? Thank you again!! <There are a
couple of variables you need to take into consideration. Usually males
get much bigger than the females. When the fish are young it is
sometimes difficult to tell. An adult male Jack Dempsey or red devil
can get up to a foot long and take over the entire tank. A female on
the other hand gets a little over half that size. The key to stocking
rates is the nitrate levels in the tank. Try to keep them under 25 ppm.
If you cannot keep these fish under those levels you need to do
more/greater water changes or keep less fish in the tank. Try and keep
all the fish around the same size.-Chuck>
Compatibility with jd fry? - 1/17/08 Tankmates For
Young Jack Dempsey's I have 4 jack Dempsey fry about 1 cm big
in my 55 gal. hex tank. They are by themselves, What other fish can I
put with them that they can grow up with? other than a baby plecostomus
(sp?)? < At this size you can add other Central American cichlids
that are about the same size. When the fish get about 10cm they may
start to pair up. When they get ready to spawn they will drive all the
other fish up away from the spawn. They may even kill the other fish
and take over the entire tank.-Chuck>
Jack Dempseys in communities 12/30/07
Hello, I really wanted to get jack Dempsey cichlid but the online
sources said they were aggressive. Is this true? <Yes. Do note that
they are named after a famous boxer rather than, say, a Rudolph Nureyev
or George Gershwin.> I have a community tank containing 3 neon
tetras, 5 tinfoil barbs, 1 platy and 5 baby platy, 2 balloon molly, 2
swordtail, and 3 Plecos. <Apart from the Plecs, the rest of the fish
here will likely be eaten, beaten up, chased, or killed.> I have a
50 gallon tank and I wanted to know if jack Dempseys are aggressive
toward these fish. Also is territorial and aggressive the same thing.
<Not always exactly the same, to be sure. But all territorial fish
will be aggressive towards anything that swims into their territory. In
some cases, the level of aggression is manageable. Angelfish guard
territories about 30 cm in diameter and outside of breeding aren't
overtly aggressive at all. Jack Dempseys, on the other hand, hold large
territories and are much more aggressive even when not breeding.>
Are fishes territorial only when you have an overcrowded tank?
<Territoriality is innate and unrelated to crowding. In overcrowded
tanks, you can prevent fish from creating territories, and therefore
they don't become maximally aggressive. This is how Mbuna are often
kept. But this doesn't mean the fish aren't aggressive, they
are, but the aggression is at a lower level than otherwise. Still, this
system isn't 100% reliable, and does depending on water quality
being maintained very well. There's no point having fish that
aren't killing each other but still die from nitrate poisoning.>
Also, do you know any inexpensive cichlids that are not very aggressive
and can be kept in a community aquarium? Thanks for all your help.
<Lots and lots of options here. In big tanks, Oscars and Severums
are both very good, as are Festivums if you can find them. Blue Acara
also work very well. In smaller tanks, Pelvivachromis spp.
("Kribs") work very well, as do Keyhole Acara and
Flag/Sheepshead Acara. Rams are not a good idea because they need very
specific conditions to survive. In brackish water, Orange Chromides
work very nicely, and will do well with Mollies (which prefer
brackish/salt water over plain freshwater). You can also keep Labyrinth
fish instead of cichlids: Ctenopoma and Microctenopoma are interesting
and often fairly mild fish, assuming their tankmates aren't small
enough to eat whole. Ctenopoma acutirostre, for example, is a very
beautiful fish that thrives on a diet of chopped seafood, small
earthworms, and frozen bloodworms. It is known as the "leopard
bushfish" in the trade and is common and inexpensive. One of my
personal favourites. Cheers, Neale.>
Re: Jack Dempseys in communities 12/30/07 hi
again, you mentioned that I could get an Oscar cichlid. I was thinking
about getting this fish and the online sources also told me it was
aggressive. Is it still okay to keep it with the fishes I have already?
<Oscars are territorial when breeding, but are otherwise fairly
placid when kept in quiet communities with other docile but big fish.
They are routinely kept with things like Tinfoil barbs, large Gouramis,
spiny eels, etc. They will of course eat anything small enough to
swallow, so you'll have to be intelligent about choosing tankmates,
and keep them with tankmates of equal size. Do be critical about
"online sources". Anyone can publish anything on the
Internet; books are recommended for inexperienced aquarists because the
facts will have been edited and checked by experts before publishing.
Likewise, most of us here at WWM have been published in books and
magazines, so advice you get here is much more reliable than something
scraped off a web page someplace. Cheers, Neale.>
Jack Dempsey in community??? 7/22/08 Hello,
Crew/Neale I'd like to keep Jack Dempsey in my 55 gallon tank.
<Certainly do-able, but not necessarily with tankmates!> I
understand that this fish is extremely aggressive and it is recommended
to keep on their own in 55 gallon tank. <Correct.> I was planning
to add Royal Pleco (much bigger than Jack Dempsey) and group (5-6) of
silver dollars (to make some movement in the tank) first, and after
that add baby Jack Dempsey. Do you think that setup might work?
<Quite possibly. The Panaque is certainly proof against the JD, and
at up to 60 cm when mature, something like three times the size. But
the Silver Dollars I'm less sure about. Not that they aren't
big/fast enough to avoid trouble -- they are -- but in a 55 gallon
system I'm not convinced the Silver Dollars will have the space
they need. You will need at least 6 specimens for them to school, and
the schooling is essential if they are to avoid trouble. I'd be
looking to keep a group of Silver Dollars in a much bigger tank. In a
"mere" 55 gallon system, I think I'd be looking at
smaller, less hyperactive fish. Perhaps Giant Danios or Clown Barbs...
something in the 10-15 cm size bracket, and deep bodied enough it
doesn't obviously look like food. JDs are of course mostly
insect/plant eaters, but they can (and will) eat small fish given the
chance. One thing I'd say in favour of big Danio/Devario spp. would
be that they'd stay resolutely close to the surface, and so would
be more dither fish than a threat to territorial cichlid pairs.>
Thank you, Mark <Hope this helps, Neale>