Mormyrid fish in aquaria

[MormyridGirl89]

Note: I'm new to this forum. As far as aquariums go, I would say I'm a beginner but not completely new. I have a 20 gallon setup for a betta fish. He passed recently at the age of 5. Please be kind as I may ask stupid questions.

I've had an obsession with mormyrid fish since I first saw one as a kid back when Walmart used to sell live fish. I've always wanted one! However, there doesn't seem to be a ton of information out there, and the information that does exist seems to differ from website-to-website. I hope to hear from those who have kept mormyrids in aquaria.

1. At first, I wanted to keep the most common mormyrid in aquaria -- elephant nose fish (petersii). However, I've read that they get depressed when kept alone and that they do best in a big group. I'm looking for a fish that I can keep solo (no other fish) as a wet-pet. Does anyone have experience keeping a single petersii? Of course, I'd be in the position to offer a large enough tank and plenty of stimulation (live food for foraging in sand, ping-pong balls, etc.). Also, since they are pretty small when they arrive, would keeping him in a 20 gallon for a couple of weeks until my 60 gallon arrives be ok?

2. I also looked at the dolphin mormyrid (longirostris, kannume, etc.) because I was told they do well alone as long as they have mental stimulation. However, I've read that in the wild they grow to 30+ inches which is way bigger than I can handle. Does anyone know if this is the size they reach in aquaria? Of course, I would never get one if I can't provide for a happy and healthy life. My limit is a 125 gallon tank.

3. I've read that mormyrids cannot handle most aquarium chemicals and medicines because they do not have scales. What about the products that are typically added to tanks during water changes (water conditioner, etc.)?

Thanks ahead of time!!

 

[Trouser Cough]

I've done a lot of water changes over the years. I purged and replaced 400 gallons yesterday. I don't think I've ever used a water conditioner or similar chemical during any of them though. Have you tried a WC w/out?

I've seen the elephant nosed fish over the years but never had one of them. Skin is a little bit of a game changer but it's not huge. I've got several fish in my tanks now that have skin, no UV sterilizer on the tank and have never had any health issue of any kind over multiple years. For fish that I know may be a little more difficult to treat I usually prefer to have a UV sterilizer on that filter return. They're not cure-alls but they definitely help mitigate some of the unintended nonsense that can grow along w/ your fish.

 

[MormyridGirl89]

I've done a lot of water changes over the years. I purged and replaced 400 gallons yesterday. I don't think I've ever used a water conditioner or similar chemical during any of them though. Have you tried a WC w/out?

I've seen the elephant nosed fish over the years but never had one of them, either. Skin is a little bit of a game changer but it's not huge. For fish that I know may be a little more difficult to treat I usually make sure I have a UV sterilizer on that filter return. They're not cure-alls but they definitely help mitigate some of the nonsense that can grow along w/ your fish.

Thank you! I just assumed (because the petshop owner told me) that I needed to use water conditioner because tap water has chlorine and other chemicals/metals in it. So, I usually remove water bucket-by-bucket and then treat/replace new tap water bucket-by-bucket. It's super time-consuming even for a 20 gallon.

 

[Trouser Cough]

That pet shop owner might be on to something. I don't know where you live (and wherever that may be I don't know what the water parameters are like there) so it's possible that you need to do something that I don't however, if you have chemicals and metals in your water the conditioner isn't neutralizing or removing any of them and your bucket-to-bucket WC method is probably allowing much of the residual chlorine to off gas and dissipate during that agitation though there are far better water chem gurus than I on this site that will be better able to address that.

Nicely done keeping the betta for 5 years. Good luck on your next!

 

[Fallen_Leaves16]

Mormyrids are generally a massive pain to keep; almost all of them eat nothing but live (usually blackworms) when first imported, are VERY sensitive to most meds (virtually untreatable; tried medicating a trio of longirostris with a very low dose of praziquantel and they started floundering after a couple hours) , and are often restless and mildly belligerent towards conspecifics and other fish that get in their way. I've heard longirostris seems to hit ~25in max when raised in captive conditions since the fish was only a couple inches, but I do have my doubts and haven't been able to confirm nor deny this. Petersii get pretty darn large compared to what people usually expect, at a maximum size of up to 12+ inches (seen a freshly imported group of them that were massive compared to the more commonly imported size). No experience with kannume; heard they're a bit smaller and more peaceful than longirostris, though. I think most fairly common mormyrid species (with the probable exception of bluntnose or "mini whale" species) get pretty big.
Contrary to popular opinion, I don't really think a lot of mormyrids really care too much about company; if they do, they don't make it much of a priority (at least in captivity). I haven't noticed any different behaviors between longirostris, petersii, and a bluntnose species whose name currently eludes me when kept either individually or in a group.
The elephantnoses and bluntnoses really don't seem very interactive, though; they're often quite skittish and spend most of the time either foraging for food or resting/hiding. "Dolphin-snouted" mormyrids do seem much more fascinating from a behavioral standpoint, but most (if not all) don't really seem very practical to keep long-term.
The main reason why I quit keeping them a long time ago is because of their diet. They are very finicky eaters and will only accept certain live or frozen foods- never had a single mormyrid take pellets or flakes. Had quite a few smaller individuals starve to death by flat-out refusing to eat. Most ate live blackworms that I attempted to culture (somehow failed), and a few would take frozen brine and bloodworms. Owing to their small mouths, mormyrids in general are pretty poor eaters and spend the vast majority of their time browsing for food in the substrate; it probably takes a single elephantnose a good hour or more to eat as much as one cube of brine shrimp, which evidently leaves a fair amount of waste and problems for the fish if it gets outcompeted by its tankmates (a very frequent occurrence). I suspect the reason most mormyrids rarely grow large or quickly in captivity is because they almost never get adequate nutrition, kind of like the gold nugget plecos of the Baryancistrus genus.
I'd expect that mormyrids require mature tanks, as I highly doubt they'd be able to tolerate fluctuating parameters without issues.
In terms of enrichment, I don't really think ping-pong balls and plastic hoops (like what some people provide for their fish) do much for mental stimulation (may be different for the "bottlenose" species, i.e. kannume, longirostris, etc), and most mormyrids prefer a substantial amount of plant and wood cover with varying degrees of flow.
Oh, and they seem to really hate magnets; I made the mistake of accidentally dropping one of those magnetic food clips for tangs into a tank with a young longirostris without realising it and later found the fish in a rather agitated state, glass-surfing on the opposite end of the tank where the magnet was. Makes sense, as they're supposedly quite reliant on electricity.
Water conditioner (and other similar additives, like API Stress Coat) is perfectly fine; never had issues with that. Haven't messed around with some of the mineral-altering or pH-stabilizing products out there, so I can't speak for those.

All things considered, I'd say mormyrids are alright for anyone dedicated and able to sacrifice some time and resources for the fish; they're definitely not the easiest to keep, but still fascinating and pretty worthwhile for the most part.

 

[MormyridGirl89]

Mormyrids are generally a massive pain to keep; almost all of them eat nothing but live (usually blackworms) when first imported, are VERY sensitive to most meds (virtually untreatable; tried medicating a trio of longirostris with a very low dose of praziquantel and they started floundering after a couple hours) , and are often restless and mildly belligerent towards conspecifics and other fish that get in their way. I've heard longirostris seems to hit ~25in max when raised in captive conditions since the fish was only a couple inches, but I do have my doubts and haven't been able to confirm nor deny this. Petersii get pretty darn large compared to what people usually expect, at a maximum size of up to 12+ inches (seen a freshly imported group of them that were massive compared to the more commonly imported size). No experience with kannume; heard they're a bit smaller and more peaceful than longirostris, though. I think most fairly common mormyrid species (with the probable exception of bluntnose or "mini whale" species) get pretty big.
Contrary to popular opinion, I don't really think a lot of mormyrids really care too much about company; if they do, they don't make it much of a priority (at least in captivity). I haven't noticed any different behaviors between longirostris, petersii, and a bluntnose species whose name currently eludes me when kept either individually or in a group.
The elephantnoses and bluntnoses really don't seem very interactive, though; they're often quite skittish and spend most of the time either foraging for food or resting/hiding. "Dolphin-snouted" mormyrids do seem much more fascinating from a behavioral standpoint, but most (if not all) don't really seem very practical to keep long-term.
The main reason why I quit keeping them a long time ago is because of their diet. They are very finicky eaters and will only accept certain live or frozen foods- never had a single mormyrid take pellets or flakes. Had quite a few smaller individuals starve to death by flat-out refusing to eat. Most ate live blackworms that I attempted to culture (somehow failed), and a few would take frozen brine and bloodworms. Owing to their small mouths, mormyrids in general are pretty poor eaters and spend the vast majority of their time browsing for food in the substrate; it probably takes a single elephantnose a good hour or more to eat as much as one cube of brine shrimp, which evidently leaves a fair amount of waste and problems for the fish if it gets outcompeted by its tankmates (a very frequent occurrence). I suspect the reason most mormyrids rarely grow large or quickly in captivity is because they almost never get adequate nutrition, kind of like the gold nugget plecos of the Baryancistrus genus.
I'd expect that mormyrids require mature tanks, as I highly doubt they'd be able to tolerate fluctuating parameters without issues.
In terms of enrichment, I don't really think ping-pong balls and plastic hoops (like what some people provide for their fish) do much for mental stimulation (may be different for the "bottlenose" species, i.e. kannume, longirostris, etc), and most mormyrids prefer a substantial amount of plant and wood cover with varying degrees of flow.
Oh, and they seem to really hate magnets; I made the mistake of accidentally dropping one of those magnetic food clips for tangs into a tank with a young longirostris without realising it and later found the fish in a rather agitated state, glass-surfing on the opposite end of the tank where the magnet was. Makes sense, as they're supposedly quite reliant on electricity.
Water conditioner (and other similar additives, like API Stress Coat) is perfectly fine; never had issues with that. Haven't messed around with some of the mineral-altering or pH-stabilizing products out there, so I can't speak for those.

All things considered, I'd say mormyrids are alright for anyone dedicated and able to sacrifice some time and resources for the fish; they're definitely not the easiest to keep, but still fascinating and pretty worthwhile for the most part.

Wow! First, I want to thank you for sharing your experiences with these interesting and mysterious fish. I think I feel more swayed towards petersii now. I don't really mind if he or she is interactive (that would be a plus), but just watching one go about its natural feeding, swimming, etc at night would be a pleasure. Like I said, I've had an obsession with them since youth. The food issue scares me a little. I don't plan on keeping anything with my petersii (maybe a mystery snail?). Competing for food wouldn't be an issue. I can get frozen and dehydrated food easily. Live food might be trickier. Would it be rude or odd to ask the pet store if they have any that are currently already eating frozen? I'll look into what I can do in terms of plants and wood to make the 50 gallon as close as possible to its natural habitat.

I think the "dolphin" mormyrids are too much mormyrid for me.

Again, BIG thanks

 

[phreeflow]

I’ve had a group of elephantnose and they were aggressive with each other but completely peaceful with other fish. Didn’t really have issues feeding them and they did fine with frozen and eventually picked at pellets. I used Seachem Prime to dechlorinate and all was fine until I added some ich meds…one of the newer formulations that are safer for scales less fish. Have used it many times with loaches and plecos without issues. But the elephantnose were way more sensitive and immediately got red sores and patches and areas that looked like the skin was peeling. Never seen anything like it. Lost some over a few days and the rest floundered, even with lots of fresh water changes.

 

[duanes]

One important part of keeping them, is providing a soft sand substrate.
They like to use that "elephant nose" as an antennae like probe shooting mild electric impulses in and thru the sand to locate buried prey like worms, or insect larvae.
I tried them decades ago, when typical aquarium gravel was the norm, and the sharp, large pieces caused minor injuries leaving lesions open to fungal infections.

The large species (and 25" is "not" an exaggeration), prey on and eat 4 to 5" cichlids in Lake Malawi. at night (they are nocturnally active)

If you keep petersii , its one of the soft water low pH variants, (But if you have hard water) , if the chlorine level of your tap water is low enough, a weak acid (such as lemon juice (acetic acid)) can be used to dechlorinate.

 

[MormyridGirl89]

One important part of keeping them, is providing a soft sand substrate.
They like to use that "elephant nose" as an antennae like probe shooting mild electric impulses in and thru the sand to locate buried prey like worms, or insect larvae.
I tried them decades ago, when typical aquarium gravel was the norm, and the sharp, large pieces caused minor injuries leaving lesions open to fungal infections.

The large species (and 25" is "not" an exaggeration), prey on and eat 4 to 5" cichlids in Lake Malawi. at night (they are nocturnally active)

If you keep petersii , its one of the soft water low pH variants, (But if you have hard water) , if the chlorine level of your tap water is low enough, a weak acid (such as lemon juice (acetic acid)) can be used to dechlorinate.

Thank you! I've heard pool filter sand is a good soft substrate for them. Do you think that would be ok? I'll definitely forgo the large species. As fascinated as I am by them, there's no way I could provide one with a happy and healthy home. I'm now set on one petersii as a solo-pet in a 55gallon. MAYBE a mystery snail with him, but I have a feeling he might bully the snail, so maybe not.

Could you recommend a good water testing kit that isn't too complicated to use?

 

[MormyridGirl89]

I’ve had a group of elephantnose and they were aggressive with each other but completely peaceful with other fish. Didn’t really have issues feeding them and they did fine with frozen and eventually picked at pellets. I used Seachem Prime to dechlorinate and all was fine until I added some ich meds…one of the newer formulations that are safer for scales less fish. Have used it many times with loaches and plecos without issues. But the elephantnose were way more sensitive and immediately got red sores and patches and areas that looked like the skin was peeling. Never seen anything like it. Lost some over a few days and the rest floundered, even with lots of fresh water changes.

Thank you! Can I ask what their main frozen food was? I've heard everything from chopped beef heart to brine shrimp.