FAQs on Jack DempseysÂ Compatibility

FAQs on Jack Dempseys Compatibility

Related Articles: Jack Dempseys, Oscars, Neotropical Cichlids, African Cichlids, Dwarf South American Cichlids, Cichlid Fishes in General,

20 Gal Long Juve JD Cichlid-any other ok? 8/18/16
Hello,
<Ashley,>
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 out!
<Nasty.>
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 known treatment.>
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.
Cheers, Neale.>

Silver dollar and E. Blue Jack Dempsey? Comp.? 8/24/12
First off, I love your site. It's an invaluable tool for any fish keeper.
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 extra mechanical.
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.
<I see>
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.
-Matt
<Sage as in the herb I take it. Cheers! Bob Fenner>

Ornate Bichir and Jack Dempsey (comp. problems) 12/3/11
Greetings,
<Salutations>
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 violent problems?
<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 body,
bought to replace Plecostomus of large size and nasty bichir-harassing habits)
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 long.
Either he will kill the Convict or she will injure or stress out him.
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 down.
Possible choices:
1 or 2 convict females;
1-2 Rainbow cichlid;
Salvini? (gets large, but I had kept one that was very peaceful before)
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 (1.5-inch
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 EBJD.-Chuck>

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 Jaguar cichlids
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, Neale.>

Jack Dempsey, comp. 9/3/11
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
larger.>
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. Cheers, Neale.>

Jack Dempsey and Oscar in 60 gal tank 7/25/11
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 Oscar.
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 along indefinitely.>
Sent from my iPhone
<Sent from my computer. Cheers, Neale.>
Re: Jack Dempsey and Oscar in 60 gal tank 7/25/11
Any books you could recommend that would say which cichlids can live together?
<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, Neale.>

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 color??
<Stress.>
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 gallons.>
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, too.>
I have already tested the water today and all the levels came back normal.
<Meaning what? What is the hardness? The pH? The nitrite level? The nitrate level?>
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 4/22/11
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
Dear WWM,
<Hello Jake,>
I'm only 15 but I have a great interest in fish.
<Cool!>
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.
<Sure.>
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 size?
<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 Loaches.>
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
<Cheers, Neale.>

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 bad.>
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 tankmates.>
Thank you for your time and valuable (to me and many) advice!
< No problem-Chuck>
Branon

Oscars in same tank with electric blue jack Dempseys 7/12/09
Hi,
<Hello,>
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 fish.
<I see.>
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 octofasciata --
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 point.>
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.>
Rachelle V
<Cheers, Neale.>

Can I put a Iridescent Shark and a Jack Dempsey together? <<BobF's go>> 3/28/09
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.
<Modesty forbids...>
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. Cheers, Neale.>

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 can.-Chuck>

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 possible.-Chuck>

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>

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