The Freshwater Dolphin Fish / Freshwater Baby Whale is a rare fish in the trade and nearly impossible to properly id them. There are a few different species under this common name and their personalities vary slightly. A few species are Mormyrus Longirosis, Mormyrus Kannume, Mormyrus Lacerda, Mormyrus Rume, and Mormyrus Tapirus. While some may be more outgoing than others, their care is fairly similar. Not much is known about this fish still, but we will share what I have gathered.

Difficulty: 5/5
Tank Minimum: 125 gallons or 475 Liter
Water Temperature: 25C to 27C or 77F to 81F,
PH: 6.7-7.3
Maximum Size: 30″
Tank Region: Middle to Bottom Dwelling
Behavior: Semi-aggressive, conspecific aggressive
Diet: A variety of worms, crustaceans, daphnia, try giving dry Bloodworms. dry Tubifix worms 
Compatibility: Tankmates can be tricky. Larger, peaceful species. Avoid other electrical fish

Approximate Size sold: 2.5 inch +

Environment

 Dolphin’s new set up. Unfinished but functional. PVC for extra hiding, floating fake plant, anacharis, and duckweed-type for Chipz the gourami and to diffuse lighting more. Low lighting plants Java Moss, Anubias, Crypts, Java Fern.

The first important thing is to keep this fish on a soft sandy substrate with no sharp edges that will injure their nose. They spend most of their day burrowing their faces deep in the sand searching for worms and tasty food, so putting them on anything besides this can keep this fish from behaving naturally. I have kept them in a PH that varies slightly between 6.5-7.2 and have not seen a significant difference, though I will say that in the wild they live in the rivers just outside the rift lakes. So while they may not require a high PH like rift cichlids, they seem to do best with a more neutral PH rather than an acidic one.  I have found that the temperature they are kept at isn’t as flexible as other species of fish and notice that their behavior changes greatly if the degrees are off slightly.  We have found that they have been happiest between 25C to 27C or 77F to 81F, 81F being the warmest. When kept warmer, they have seemed to breath heavier and were much more agitated. They prefer dimly lit aquariums so a lower light or “spot” lighting is a good choice. A brightly lit aquarium may make the dolphin shy and hide more. While they like a lot of hiding, it is important to have some areas of open water on the ground. This will allow them to display their natural behavior digging around, as well as allowing them to swim freely without bumping into things constantly. Speaking of which, because they are fairly blind and rely on their electrical pulse to navigate; they can and will bump into objects (especially if you rearrange your decorations) so it is important to choose decorations that do not have any sharp edges.

They spend most of their day burrowing their faces into the sand looking for worms

Use care when choose live plants to house with the dolphin. For example, a plant that requires a high light is probably an unwise choice since either the dolphin or the plant’s needs will not be met. Delicate plants that the dolphin can  tear up or un-root while they forage are also not a good choice. You can add in taller plants, but keep them sparingly or in designated spots because a heavily planted tank, especially with tall plants will make it difficult for the dolphin to swim freely and can also get them tangled up. If you’re into aquascaping and keeping your plants neat, the dolphin will keep you frustrated as they are the Godzilla’s of the plant world; making it a game to destroy your favorite plants.

Diet

Their diet will likely vary between individuals but I found that it’s vital to have worms as a staple. While bloodworms are easy and can be used, I would advise against using these as the only source of food. Variety is best which should include blackworms, white worms, grindle worms, and larvae. I’ve tried clean earthworms as a treat, and they seemed to enjoy these, as well; though may be too large for  smaller specimens. While live is ideal, you run the risk of spread disease this way. To avoid risking disease, getting your worms from a reputable source or cultivating your own is recommended. Dolphins will also accept daphnia and possibly crustaceans such as brine and mysis.

Behavior

As stated before, these fish are a semi-aggressive species. Their personalities will vary among individuals and even more so among species. My experience with what I believe to be Lacerda is an interesting one. From the start, both of my dolphin have been dolphin outgoing. They seem un-phased by new environments and seem to always go with the flow. They have been some of the easiest fish to catch because their curiosity always gets the best of them and will voluntarily hop in my net. If I put my hand into the aquarium and rub my fingers together, the friction of my fingers undoubtedly will always bring them both out no matter the time of day to investigate. I suspect this has something to do with the movement my fingers give off that they pick up on their electrical pulse.

Everything seems to be a game to them. The behavior does not come off as aggressive, and they’ll gently nuzzle my hands to see if I have food for them. Feeding time is also a game to them; even when they find the source of the food, they will only eat a small portion before they swim off to “find” it again as though they require a challenge.

Toys may be a good option as they are extremely intelligent and may benefit from something that will stimulate their minds. I keep some moss balls in my aquarium and my largest dolphin will spend the day bouncing it around the aquarium like a beach ball. I have seen others put balls, hoops, and other interesting enrichment toys in their aquarium.

The “Don’ts”

Like other electrical fish, Mormyrid are a scale less fish. This means that they can be extremely sensitive and intolerant of medications and salt. For this reason, it’s all the more important to not only quarantine your new dolphin, but to quarantine any potential tankmates as well; because if disease does occur, it can be very difficult to properly treat. There are some medications that can be used, but any medications that contain copper need to be avoided at all costs. I will be writing an in-depth section on the types of medications and which are safe for scale less fish so stay tuned. Regardless though, prevention is the best form of medication.

The other thing to avoid are metals. This means anything that could potential leech metal into the water (such as fake plants from a craft store) and any buffers that may contain things such as iron. Buffers that could contain iron and other hazardous ingredients would be many of your plant buffers. Another reason to use care when choosing your plants, as demanding plants who may need these products are an unwise choice. So far we have had success in using Seachem Flourish Tabs safely, but remember to always use the product properly.

Tankmates

The larger dolphin did not “approve” of rabbit snails and would knock them as though they were a football.

Tankmates are tricky with dolphin. They are bullies and will harass any fish they deem unworthy, but it’s also important not to keep this fish with others that could injure them or stress them out. Some species are particularly shy, so these fish may do best with calmer tankmates to encourage them to explore. One thing that is noted is that they do not do well with other electrical fish. It’s unsure why this reason is, but it may have to do with the pulses other species give off as being irritating to them. They also don’t seem to do well with their own kind, though in the wild they are known to be gregarious. I have been experimenting with these fish to find out first hand how they behave.

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