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FAQs on Mormyrid Fishes Selection

Related Articles: Mormyrids, ElephantfishesElectrogenic Fishes,

Related FAQs:  Mormyrids, ElephantfishesMormyrid Identification, Mormyrid Behavior, Mormyrid Compatibility, Mormyrid Systems, Mormyrid Feeding, Mormyrid Disease, Mormyrid Reproduction, Bony Tongue Fishes, Electrogenic Fishes, Aba Aba Knifefish, African Butterflyfish, Arapaimas, Arowanas, Featherfin Knives, New World Knifefishes,

Mormyrids... Stocking tog., beh.     2/7/12
If Mormyrids are crowded, does this bring out a different behavior that is sustainable and can they put up with the presence of many other Mormyrids in close proximity without being stressed by each others fields?
<Does seem to be the case in retailers' tanks'¦ but whether sustainable long-term at home, I cannot say. Would not recommend overcrowding any fish as sensitive as these.>
Does this video show there is a benefit to crowding them, and they are adapted to put up with large groups of their own kind, like with Tropheus?    
<And even with Tropheus, there are huge problems with nitrate-sensitivity, filtration.>
The person who has that tank said that out of the Mormyrids he has Campylomormyrus tamandua is not very aggressive in groups, is that well known to be true?
<The species is not commonly kept, so it's hard to say. Baensch describes them as "peaceful loners" and comments that in groups bigger ones bully the smaller ones, preventing feeding. So your problem may be a long time in coming, with fish seemingly coexisting for weeks, months until the weaker ones starve.>
Also wonder what the guidelines are for petrocephalus, they are schooling and small so how much room and how big a school is needed to keep them.  And they still need pvc pipes to hide from each other?  Is a 3' tank too small for a school of petrocephalus, will they eventually breed and kill each other in that size tank?
<Would treat as any other medium-sized, delicate schooling fish, such as Glass Knifefish. Oversized tank, oversized filter relative to their size. Get the tank up and running for some months before introduction. Maintain with peaceful tankmates selected to play the role of dither fish (surface-swimming Rasboras or Danios for example) rather than anything midwater or benthic. A tank upwards of 55 gallons with a filter rated at not less than 8 times the volume per hour would seem prudent. As with all Mormyridae, the more caves, tubes, robust plants the better. Although gregarious, that doesn't mean this species "likes" its own kind -- just as with any schooling fish, even Danios, the stronger will be bullying the weaker, albeit rarely to the point of death. Rather than keeping 6, aim to keep 10 or 12.>
<Cheers, Neale.>
Re: Mormyrids    2/9/12

Why are Mormyrids so sensitive to chemicals and metals, in a way most other fish aren't?
<They just are. All fish are sensitive to copper and formalin and suchlike.
But some are more sensitive than others, and Mormyridae are at the very sensitive end, like Stingrays.>
I know they're stress prone and aren't treated properly usually, but the water issues, is their one trait that makes Mormyrids so frail in that way?
<Pretty much everything about them is demanding.>
The article on them on WetWebMedia says to treat tap water and let it stand for a weak, ideally. Is there a tap water test to tell you if your tap water is likely to kill them?
<Water chemistry actually doesn't matter much. So your issues are ensuring copper and ammonia are neutralised, as well as the usual chlorine and chloramine. Mormyridae aren't killed so much by bad water as bad water quality.>
It seems like there are many possible ways for that to happen, so I'm curious as to why.
<Just is. Cheers, Neale.>

Re: My first aquarium... Bichir hlth., Mormyrid sel.   12/28/09
My bichir has developed a white mossy growth covering much of his body.
The rest of the tank seems fine. Is this the Ich I hear about?
<No; is likely Finrot and/or Fungus. Treat promptly but with great care:
formalin and copper-based medications can be lethal to Bichirs, Mormyrids, Catfish and Loaches.>
I have a baby whale in the tank along with a Featherfin catfish and the ill bichir.
<"A" Baby Whale (Pollimyrus sp.) won't last long... these are highly gregarious fish that should be kept in groups of at least five specimens. Singletons tend to pine away, while groups of 2, 3, or 4 often end up with one bully and the rest dead... and of course the remaining bully ends up pining, so then there are zero. Do always read up on fish prior to purchase.>
Many thanks for your help.
<Cheers, Neale.>
Re: My first aquarium
Ouch I tried but came up with little info.
<Often the case with fish that have a poor survival record in captivity.
While books (and, if I might modestly add, expert fishkeepers like me) will usually have something to say about Mormyrids and other "difficult" fish, online sources put together by the vast majority of hobbyists concentrate
on fish species that are relatively easy to keep. Instead you need to pick up a copy of something like Baensch's Aquarium Atlas volume 3 you'll find Pollimyrus listed and briefly described.
What kind of timeline does he have?
<Really does depend. A single specimen may well thrive if tankmates are smaller than it is, and it can feel settled and secure. But with tankmates of similar or larger size it will feel more nervous, and the more nervous it is, the more stressed it can become.>
I don't know if there are four more in the city. I've been looking.
<I see.>
He is eating well right now.
<Good. With Mormyrids generally, while eating well, they're basically healthy and easy to keep; but as soon as they have problems getting enough to eat, their condition worsens, and they become much weaker. Good water
quality, including a high oxygen concentration, is important.>
I have purchased a "naphthoquinone" based product. Will that work?
<Should be.>
PS: do you guys take donations? I'm starting to feel like a pest.
<Yep, you're welcome to buy us a beer. Do see the Donate button at bottom right.
Don't worry about feeling like a pest; this site works precisely because we get lots and lots of interesting questions. Besides, we aren't selling anything, we're all volunteers, and we really do want to help. Cheers, Neale.>

I have a question concerning convict cichlids comp. and elephant nose sel. 01/21/2008 <Ask away.> Ok... Are elephant noses hardy fish? <Not even close to being hardy. Among the most difficult freshwater fish commonly traded.> What is the minimum tank size for one? <On its own, likely around 150 l/40 gallons. They get pretty big if kept properly. In a community setting, much more space is needed, because they are territorial and their electric field does irritate some fish.> Also, do they need to be put into groups, I was planning on getting just one. <Elephant noses are best kept either singly or in groups of six or more. In twos and threes they tend to be unpredictable, and sometimes quite nasty to each other. Wild fish do live in schools though, so singletons are, unsurprisingly, rather shy (i.e., you don't see them most of the time).> My other question is, are convicts really that aggressive, because I have friends who own these and they say they have had success keeping it with zebra danios. <Define "aggressive". Yes, Convicts are (for their size) very aggressive towards anything they deep as either a rival for nesting space or a potential predator on their offspring. So despite being relatively small cichlids, they are best kept in (big) community tanks that only include larger cichlids, such as Jaguars and Red Devils. On the other hand, in a spacious enough aquarium, Danios might well be ignored. The use of Danios and other surface-living fish has been widely documented among cichlid-keepers as sometimes beneficial. Such "dither fish" as Danios encourage the bottom-dwelling cichlids to stay out in the open more. So would such a combo work? Quite possible. Is it a good idea for the less experienced aquarist? Probably not.> From your experience, are they really aggressive? <I've kept Convicts in a 200 gallon tank with a Red Devil, a Jaguar Cichlid, some Firemouths, a Channel catfish and a Gar. They all got along fine. Read from that what you will, but I'd make the point that the Convicts were holding their own in a big tank filled with potentially aggressive and/or predatory tankmates.> Will it be fine to keep it with n elephant nose? <Absolutely not.> Thanks for your time and thank you for your help. <Happy to help, Neale.>

"Freshwater dolphin" too vague... (Mormyrid search) I think I've fallen in to the trap of "common names" being used among those who don't know the difference (myself included). <Easy to do> I have been looking for a M. tapirus and as of late had little luck. <The "Western" Dolphin... don't think I have ever seen this species offered in the West (the U.S.)... comes out of Cameroon and Guinea... sometimes imports from here are offered in Germany, other European countries> However, I was speaking with a LFS as he received his weekly "list" and he said "oh, I can get the freshwater dolphin you've been wanting".  I replied "oh really, the M. tapirus", he says, "uh, yeah, sure, it's the Mormyrus dolphin".  Well, I asked to verify, we looked up a picture and I chanced it.   The fish will be in later this week and I'm now thinking it may be a M. longirostris.  It seems these two species are very similar and even both are commonly referred to as a freshwater "dolphin". <Yes... the "Eastern" Dolphin is what is primarily seen in the United States>   It also seems the M. long. is much more common than the M. tap. and therefore that's why I think it's not the tap. Any thoughts? <Pertaining to what?> I've looked hard for information on the both of these, trying to find enough info to ID my potential specimen.  I use fishbase.org a lot and, based on my findings, there, I do believe the tap. is the one I really want.  I'll gladly send a pic and more info once I receive it.  Any insight would be most appreciated.  I would feel badly not taking the specimen he gets in, but I also don't want to be misinformed as to what species I actually have. In search of M. tapirus... Sincerely, Dana Irby Hendersonville, TN <Perhaps a trip to Africa? Or to Germany? Bob Fenner>

Mormyrid search Thanks for your reply.  From your comments, it sounds as though the M. tap. is not available here in the U.S. so I guess it really doesn't matter what they call it here...it's most likely M. long. <Yes> Sorry for being so wordy and vague about what I was wanting from you. Ultimately, you answered my question and any further questions regarding M. tap. would be a mute point anyway. <No worries> I'll just see what happens. Thanks again and have a wonderful day!!! Dana Irby <You as well. Bob Fenner>

Do you know where to get freshwater dolphin (Mormyrus tapirus) <Sorry, no. I have seen them at a few Fish/Pet stores. I did a search on Aquabid.com, but none listed right now. Check with the manager of your LFS. Many times fish will show up on his venders list, but are not ordered. He may be able to get them for you. Don>   Sky McDougal

The Elephantfishes, family Mormyridae, In Aquariums  - 03/14/2005 Just wanted to share my pictures of my Elephantnose.  I found your article while trying to do some research on them.  Very hard to find any information.  Hope you enjoy them. <Mmm, didn't "come through"... can you send these as jpg attachments? Will post with credit to you. Thanks, Bob F> Lesley Moravick #3 the last picture.  I hope you get them.  I just love my guy.  I have had him/her for 2 years now <Very nice. Thank you for sharing. Bob Fenner>

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