hi everybody, I just recently acquired a huge foot long freshwater dolphin mormyrid fish and have had him for a few months now and he’s very healthy, active, and eating a ton. I just wanted to add some info about him since when I was looking for care information on them it was super scarce, so I’ll add what I can.
Temperament: Very aggressive
I believe they are very different from how they are typically described, which is shy, extremely sensitive, etc. In reality, they are very hardy (mine lives in 8.3 liquid rock ph) and mine literally bullies my 2 foot redtail catfish, jardini, pacus, peacock bass, dats (which were previously the king), etc... I’ve owned almost every “aggressive” monster fish seen on river monsters (Payara, African tiger fish, piraiba) along with actually aggressive fish like flowerhorns, big cichlids, and he’s hands down the most aggressive fish i’ve ever owned. I’d definitely rank him up there with the jardini or dovii in terms of aggressiveness.
Mental capacity: Extremely personable + Extremely intelligent
Although he’s aggressive and all the other fish are scared of him, he has no teeth and so the damage done is very minimal if none. What’s surprised me the most is its intelligence. It’s related to the elephant nose and you can assume he’s pretty smart, but I totally underestimated his ability. People always talk about how intelligent their fish are but most of the time it is simply assigning meaning when there is none there. But, the dolphin fish actually will purposefully plan ahead and memorized my food puzzle after two times. Let me explain.
I put his food in a net or a jar so that other fish can’t get to it or figure out how to reach the food, and so I ensure he eats enough. I like to call it a food puzzle. He figured out how to reach the food on the first day. The other fish still try to get to the food from outside of the jar and can’t figure out how to get inside even after months. The next morning I saw all the fish on one side of the tank and thought that was strange. Then, I realized what had happened, the dolphin fish memorized that I drop in the food puzzle on the right side of the tank every time and so in his spare time he’ll herd all the fish on the opposing side like a shepherd, and he does it in expert fashion. He knows he can’t take on the 2 footers and monsters that are larger than him, so he simply pushes his body and guides them away without them realizing, until they’re all the way on the other side of the tank. For the fish smaller than him (ngt datnoid, smaller pacu), he simply aggressively chases them away, threatening them with his size. He does this every time I drop in his food puzzle. He’ll eat and stop to herd the other fish away everytime they get close, ensuring he’s the only one eating. I’ve seen aggression during feeding, but nothing this strategic where all the other fish are on the other side of the tank! Usually fish don’t have the mental capacity and just single out one fish to bully. He herds everybody and has a different strategy for each fish in order to not get himself hurt, as he knows the bigger fish would win in a full on confrontation.
Tank size: At least 30 inches x 8 feet
Unfortunately, I got to talk about tank size. I know many new fish keepers that don’t keep monster fish love the dolphin fish and wanna put them in a 10 or 20 gallon. I hate to be that guy, but they really do grow big, obviously rarely to what they list on websites, but i’d say a good 2 feet on average, so you will need a big enough tank to house them eventually. Mines still growing almost 1/2 inch a month at 13 inches.
Hardiness: Hardy
They are about as hardy as an oscar in terms of water quality, and parameters, meaning basically if you forget to do a few water changes and get busy, fish like payara or rays will die first and usually hardier fish like oscars or pacu will still survive. The dolphin fish is definitely on par in terms of hardiness. However, under 6 inches and they are extremely sensitive. I’ve tried with a .5 inch wild caught baby and it died the first day.The truth is, because they are super niche, they are all wild wild caught and during transportation never fed or taken care of, so when they land in pet stores, they are usually full of internal parasites + new diseases that they weren’t exposed to in the wild + adjusting to harder and different water. This all adds up and causes most to die within the first week, which is why I advise getting one 6 inches or above if possible as they can handle it better. Once you get him adjusted, treated, and eating in your tank, he’s an incredibly hardy fish. But you basically have to nurse them back to health. It’s the same reason why payaras, atf, and other niche fish are deemed unhardy, because little is know about their care and they are all wild caught. Although, dolphin fish adjust far better to aquaria as they aren’t specialized piscivores and are not nearly as skittish, and also are intelligent enough to know that there is a glass wall to not run themselves into. All in all, if you are lucky enough to find a fish 6 inch or bigger you will most likely succeed and keep him for , if it’s under that, you can try but it’s 9 times out of 10 going to be dead within a week or a month and money down the drain.
Appetite: Voracious, but extremely picky
This is where we probably run into the most problems with these wild caught fish, is because they aren’t like other farm-bred domesticated fish like oscars, they have no idea what pellets or man-made food is, they probably identify it as fish poop or waste. Mine has eaten some pellets but will spit them out. I’ve tried mimicking their natural diet and have had great success with worms of all sorts. They’ll gobble them up. If you can’t get your dolphin fish to accept other frozen food, you can start feeding hikari bloodworms to get their appettite going. They never refuse bloodworms. You can soak them in fish vitamins as bloodworms are mostly water and don’t contain many nutrients. Once adjusted and nursed back to health, try mixing in other worms or frozen foods with the bloodworms. I wouldn’t use the starvation method as I find that is another main cause for their frequent death rate in aquaria. They have very fast metabolisms and are always on the go, treat it like a sturgeon, under 8 inches feed them at least 4-5 times a day. I feed my 13 incher 3 times a day even at that size, where most monster fish are ok with once a day or even once every other day.
And that’s all! If you don’t wanna read the whole thing, just remember: feed very often, and get a large enough tank. Hopefully that helps any lurkers looking through the limited articles of info and in a year or two i might update this with the information i’ve gathered. They are an incredibly rewarding fish and are my favorite! They act just like a baby dolphin and are super playful, curious, and intelligent! They will recognize you immediately and will eat right out of your hand. Here’s some pics of him:
Temperament: Very aggressive
I believe they are very different from how they are typically described, which is shy, extremely sensitive, etc. In reality, they are very hardy (mine lives in 8.3 liquid rock ph) and mine literally bullies my 2 foot redtail catfish, jardini, pacus, peacock bass, dats (which were previously the king), etc... I’ve owned almost every “aggressive” monster fish seen on river monsters (Payara, African tiger fish, piraiba) along with actually aggressive fish like flowerhorns, big cichlids, and he’s hands down the most aggressive fish i’ve ever owned. I’d definitely rank him up there with the jardini or dovii in terms of aggressiveness.
Mental capacity: Extremely personable + Extremely intelligent
Although he’s aggressive and all the other fish are scared of him, he has no teeth and so the damage done is very minimal if none. What’s surprised me the most is its intelligence. It’s related to the elephant nose and you can assume he’s pretty smart, but I totally underestimated his ability. People always talk about how intelligent their fish are but most of the time it is simply assigning meaning when there is none there. But, the dolphin fish actually will purposefully plan ahead and memorized my food puzzle after two times. Let me explain.
I put his food in a net or a jar so that other fish can’t get to it or figure out how to reach the food, and so I ensure he eats enough. I like to call it a food puzzle. He figured out how to reach the food on the first day. The other fish still try to get to the food from outside of the jar and can’t figure out how to get inside even after months. The next morning I saw all the fish on one side of the tank and thought that was strange. Then, I realized what had happened, the dolphin fish memorized that I drop in the food puzzle on the right side of the tank every time and so in his spare time he’ll herd all the fish on the opposing side like a shepherd, and he does it in expert fashion. He knows he can’t take on the 2 footers and monsters that are larger than him, so he simply pushes his body and guides them away without them realizing, until they’re all the way on the other side of the tank. For the fish smaller than him (ngt datnoid, smaller pacu), he simply aggressively chases them away, threatening them with his size. He does this every time I drop in his food puzzle. He’ll eat and stop to herd the other fish away everytime they get close, ensuring he’s the only one eating. I’ve seen aggression during feeding, but nothing this strategic where all the other fish are on the other side of the tank! Usually fish don’t have the mental capacity and just single out one fish to bully. He herds everybody and has a different strategy for each fish in order to not get himself hurt, as he knows the bigger fish would win in a full on confrontation.
Tank size: At least 30 inches x 8 feet
Unfortunately, I got to talk about tank size. I know many new fish keepers that don’t keep monster fish love the dolphin fish and wanna put them in a 10 or 20 gallon. I hate to be that guy, but they really do grow big, obviously rarely to what they list on websites, but i’d say a good 2 feet on average, so you will need a big enough tank to house them eventually. Mines still growing almost 1/2 inch a month at 13 inches.
Hardiness: Hardy
They are about as hardy as an oscar in terms of water quality, and parameters, meaning basically if you forget to do a few water changes and get busy, fish like payara or rays will die first and usually hardier fish like oscars or pacu will still survive. The dolphin fish is definitely on par in terms of hardiness. However, under 6 inches and they are extremely sensitive. I’ve tried with a .5 inch wild caught baby and it died the first day.The truth is, because they are super niche, they are all wild wild caught and during transportation never fed or taken care of, so when they land in pet stores, they are usually full of internal parasites + new diseases that they weren’t exposed to in the wild + adjusting to harder and different water. This all adds up and causes most to die within the first week, which is why I advise getting one 6 inches or above if possible as they can handle it better. Once you get him adjusted, treated, and eating in your tank, he’s an incredibly hardy fish. But you basically have to nurse them back to health. It’s the same reason why payaras, atf, and other niche fish are deemed unhardy, because little is know about their care and they are all wild caught. Although, dolphin fish adjust far better to aquaria as they aren’t specialized piscivores and are not nearly as skittish, and also are intelligent enough to know that there is a glass wall to not run themselves into. All in all, if you are lucky enough to find a fish 6 inch or bigger you will most likely succeed and keep him for , if it’s under that, you can try but it’s 9 times out of 10 going to be dead within a week or a month and money down the drain.
Appetite: Voracious, but extremely picky
This is where we probably run into the most problems with these wild caught fish, is because they aren’t like other farm-bred domesticated fish like oscars, they have no idea what pellets or man-made food is, they probably identify it as fish poop or waste. Mine has eaten some pellets but will spit them out. I’ve tried mimicking their natural diet and have had great success with worms of all sorts. They’ll gobble them up. If you can’t get your dolphin fish to accept other frozen food, you can start feeding hikari bloodworms to get their appettite going. They never refuse bloodworms. You can soak them in fish vitamins as bloodworms are mostly water and don’t contain many nutrients. Once adjusted and nursed back to health, try mixing in other worms or frozen foods with the bloodworms. I wouldn’t use the starvation method as I find that is another main cause for their frequent death rate in aquaria. They have very fast metabolisms and are always on the go, treat it like a sturgeon, under 8 inches feed them at least 4-5 times a day. I feed my 13 incher 3 times a day even at that size, where most monster fish are ok with once a day or even once every other day.
And that’s all! If you don’t wanna read the whole thing, just remember: feed very often, and get a large enough tank. Hopefully that helps any lurkers looking through the limited articles of info and in a year or two i might update this with the information i’ve gathered. They are an incredibly rewarding fish and are my favorite! They act just like a baby dolphin and are super playful, curious, and intelligent! They will recognize you immediately and will eat right out of your hand. Here’s some pics of him:
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