VII. Mbu for You?

The author of this article, Manutius, is the owner of a 16″+ Mbu puffer, Clooney. Like many owners, he was told his 5 foot 90+ gallon tank was fine for the fish by the shop selling the puffer, and only later learned how enormous Clooney could grow and just how much space a full grown Mbu needs. Clooney has been with Manutius for 4 years. This article is an important read for anyone considering a fish of this size, and is also a very valuable resource for others like him who took home a small adorable puffer with no idea of its monstrous requirements.

Mbu For You?

I am very fortunate to have such a great fish. Only another puffer owner can really appreciate the relationship that these fish can provide. There is something about their face that makes you feel they are studying you as you look at them. It is not uncommon to hear a puffer owner say that their puffer greets them when they walk in the room, just like a puppy. Very few fish behave in the way that a puffer does or can match their character. While some cichlids can claim to have character, a puffer has it in bucketfulls. I shall concentrate on the Mbu puffer, as it is the species I have, but certain rules are true to all puffer species. Puffers are sensitive to poor water quality and large waste producers, therefore they require larger than average water volumes, over-filtration and large water changes. Most puffers are aggressive and as a rule should be kept in a single specimen tank, however the Mbu is one of the more laid back species and is generally more tolerant of other fish. This needs to be taken with reservation however, as few Mbu live to maturity in captivity with other fish so it is difficult to say how that might change with age. Clooney seems indifferent to tank mates at the moment he may change his outlook as he matures. I am aware of some Mbu being very aggressive and attacking everything else that was unfortunate enough to be placed in the tank.


A Few Facts about the Mbu

Tetraodon Mbu is widely spread throughout the Congo basin and Lake Tanganyika. It is pronounced “uhmboo”� but I say “muhboo”� and to be fair I’m sure it doesn’t matter. The other name often given is Gold Ringed Puffer or Reticulated Puffer and this derives from the stunning markings of these fish. The pattern of darker reticulated rings over a golden base color is unique to each individual fish and allows for great camouflage in the wild. Even a fully-grown adult can disappear before your eyes in a river and become one of the rocks, in fact the word Mbu means rock in certain African dialects! The Mbu is the largest of all freshwater puffers and will attain a maximum size over 67cm(two feet) in the wild, with potential to exceed that size if given optimum conditions in captivitiy. They feed primarily on crustaceans such as crabs, mussels, clams, and shrimp. The reason that they can tackle this hard-shelled prey is because of the very impressive beak that they have. The name of the genus to which Mbu belong, Tetraodon, literally means four fused teeth, and the pointed beak formed by the teeth can be seen clearly on the larger puffer species. These teeth are incredibly strong and continue to grow regardless of the size and age of the puffer, so it is imperative that they feed on ever harder shelled food as soon as they have the jaw power to tackle it. Without this diet the teeth become overgrown and eventually prevent the puffer from feeding at all. In the wild the Mbu will swim along and blow water at the sand bed, hunting out prey that may be buried in the river bottom tucked away safely. Their independently moving eyes allow for a great range of vision, which helps them to take in the environment around them as well as study it for food items. I am not sure if they rely solely on eyesight to find their food in the wild, but I often see Clooney blowing jets of water into gravel to uncover something beneath. Saying whether he can pick up on a tiny movement of something in the gravel or can smell something there would be purely conjecture; but from my observations of Clooney I believe there is more to these puffers than has been researched. As the term puffer suggests, these fish are able to inflate when threatened, and though they are not easily seen as with porcupine puffers, Mbu have spines under there skin which act as a deterrent to potential predators. A puffer’s defense against predators can be summed up as a warning saying, “You really don’t want to eat me”.� Puffing is a really unique adaptation, and works thusly, according to Dr. Peter Wainwright:

“After filling its mouth with water, the fish flexes a large muscle at the base of the oral valve which then catapults forward against the entire front of the mouth, forming a tight seal against the back of the front teeth. This prevents the water from escaping while a “plunger” type of apparatus mounted at the base of the throat forces the water upward where it shoots down the fish’s esophagus and into its stomach.”�

The lack of a ribcage or pelvic bones combined with a very flexible spine allows the puffer to inflate considerably, while small muscles under the skin erect the spines. I have only seen Clooney do this once, but there have been several times I saw him partially inflated in the 4 years that I have had him.

Another unique feature of puffer biology is the ability to store toxins in their skin and organs. The poison is tetrodotoxin in marine puffer, but a variant, called Saxotoxin, is present in some freshwater puffers. The puffer does not produce them itself; they come from Pseudoalteromonas strains of bacteria found in the crustaceans that puffers eat. The bacterium has no ill effect on the puffer and is only dangerous to humans if puffer flesh is eaten, contact with the fish is not dangerous. The symptoms of poisoning can include nausea, vomiting, muscular weakness, paralysis, respiratory distress and eventually death. The poison can be take effect as fast as 10 minutes or as long as three hours later. No specific antidote is known. To give an idea of how powerful tetrodotoxin is, injected intravenously less than one milligram is fatal to humans, making it over 1200 times as deadly as cyanide. There is no reason for worry for puffer owners however, as the food we give our fish are free of the necessary bacteria and therefore their stores of poison will deplete over time. However, I still do not suggest you try puffer fillets this summer on the BBQ; sushi chefs spend many years learning how to prepare puffers safely for human consumption. While it’s generally claimed there are 50-100 deaths from tetrodotoxin poisoning a year, Japans Health, Labor and Welfare Ministry reports only 14 people dead of blowfish poisoning from 2002 to 2006. Even if amateur preparations outside of restaurants (amateur preparation is much more likely to result in poisoning and much more likely to have the true cause go unreported) are taken into account, between ten and twenty a year is more likely.

The way that puffers swim is also unique, to quote Neal Monks in his article in Practical Fish Keeping:

“The way pufferfish swim compared with that of other fish is rather like comparing a helicopter to an aeroplane; while they may be slow, they are extremely maneuverable, and this allows pufferfish to spot and capture prey that other fish would simply swim straight by.”�

Propulsion for a puffer to swim is produced mainly by the small pectoral fins on the body, with the large and impressive tail used only for bursts of speed. This method of swimming allows even the largest Mbu to turn on a dime or rotate on the spot; they are diligent, thorough hunters that will not dart past potential food. The puffer will find snails or crustaceans even if they are well hidden.

Very little is known about these puffers’ habits. It is not believed that the Mbu can be sexed from external observation and information on their breeding habits is non-existent. For this reason, all Mbu that are available in the aquarium trade are wild caught in nets and then shipped to us. It is fair to say that this would be a stressful time for any fish, but puffers seem to suffer more from it. A Mbu puffer who a couple of weeks ago was free to swim in the Congo basin or a huge lake now finds itself imprisoned in a small tank with a pink castle and some bothersome fish in its personal space. It breaks my heart to see them confined like this and if anyone has seen one in their local fish store they will know what I mean.

Aquarium Care

A very well respected puffer keeper of many years and scientist has recommended a tank of about 4000 liters (approx. 1000 gallons) and I have to say that I agree that a large tank is the only way to keep these fish happy. I would say that the footprint is key, and that as a minimum size I suggest seven foot by four foot as an absolute minimum, with a height of about 3ft. In an ideal world I would go for a tropical pond or a ten-foot by four-and-a-half-foot by four-foot tank. This would give a probable volume of about 4000 litres if you allow for gravel and decoration. You then have to deal with the issue of how to filter such a tank, so a large sump and/or several large canister filters such as Fluval FX-5s would be needed. Additionally, plenty of pond heaters would be needed to keep the temperature around 26 C. All in all, an appropriate tank is a little out of most people monetary or practical range. It is also worth noting that acrylic tanks are not a good idea for large puffers, as their teeth are known for scratching the plastic, which is unsightly and may weaken it over time.

Even assuming that we have a tank large enough for a Mbu puffer to turn around in properly, we need to look at decoration and design of the tank. Varied decor with many points of interest are necessary to keep these puffers active and interested in their surroundings; again this is something a standard six-foot tank would struggle with. Ideally you would have lots of bogwood, medium grain natural gravel and large plants. Clooney loves it when I put new plants in the tank, he will always swim over to check them out. Plants that are ideal for a tank this large include Giant Vals and certain large sword plants, Clooney actually chooses to rest under sword plants when I have them in the tank. These fish are active hunting swimmers, not lurkers, the planting and decor should be spread out far enough apart or kept to the fringes and background to allow the puffer plenty of room to swim about and, crucially, to be able to turn properly.

Once you have a tank set up it will need to be fully cycled before the Mbu is added, Mbu puffers like all puffers are very sensitive to ammonia and nitrites. Though it may seem silly putting 4 inch baby Mbu in such a vast tank, I would much sooner do that than try to catch and remove a twenty inch fish powerful enough to bite your fingers off (without removing it from the water, important because like all puffers, if it inflates and traps air, it could end up dead). They prefer a PH of 7.2-7.6, while hardness is not too much of an issue. Temp needs to be between 24-28C, though the lower part of the temperature range is better as it allows for more oxygen in the water, something a large puffers uses in spades as they grow and feed. Very large puffers will use up to 40% more O2 when digesting their food, I have heard of one Mbu that suffocated in a small tank because of this, so be sure to keep the water well aerated. High volume water changes are also absolutely essential for such a large, messy and sensitive fish. Their sensitivity to any accumulating toxins is another reason for the large tank size, the bigger the tank the more dilute any poisons in the water will be. Applying the normal rules for stocking small fish is not accurate for puffers due to their messy eating, waste production, and rotund figures.

Feeding the Mbu

Photo of Clooney, a Mbu puffer, displaying his

It is important to address the natural dietary needs of these fish to keep them healthy, so shelled food is important to keep the teeth trimmed. Young puffers will benefit from snails the most, and the best types are pond or ramshorn snails. You can raise these snails either yourself as they lay eggs quickly if well fed, and they can be fed on household vegetables and fish food. Snails you raise yourself will be free of any disease or pesticides that may be present in those taken straight from a pond or local fish store tank. Garden snails may be used too, but again, they must be pesticide free and it is suggested that they be stored in a container for a few weeks while fed wholesome foods to purge anything potentially dangerous in their systems. Malaysian trumpet snails, which look similar to ice cream cones, should be avoided as it has been reported some persistent puffers have cracked their teeth on the tough conical shells of these snails. Puffers that damage their teeth may need to be drugged with clove oil and have them trimmed to even them out, not a job for the faint hearted and not one any Mbu puffer owner would want to do. The teeth overgrowing from lack of crunchy food will also necessitate trimming, and while it is easier when the puffer is smaller, trying to hold a large unconscious Mbu and get enough force with the clippers sounds terrifying. Perhaps a dremmel or power sander would be a better option, but best to avoid it entirely by giving your Mbu a proper diet. The best staple for many larger puffers would be mussels, and the Mbu is no exception. As the fish matures it can be moved onto other larger foods, such as cockles in shell, crab claws, freshwater clams, and squid. Another good food is ghost shrimp; ideally these can be kept in a separate tank and fed up on veggies to gut load them, conveying some greens and vitamins to the puffer. I believe variation is the key to a good diet, Clooney eats almost anything I put in for him, mussels, clams, cockles, bloodworm, and prawns. Crab claw is a real favorite, and he absolutely loves Hikari brand algae wafers. He will also spend some time tearing up the tank up chasing live shrimp, which is very fun to watch.

In Closing

While I hate to end with such a down note on these great fish, I do not believe they belong in the general fish trade. They should only be made available on special request to someone who can care for and house them properly. If I had it to do again knowing what I do now, I would not have purchased Clooney for my 5ft tank. I was assured that he would be okay by my local fish store, but with how large he is now, his tank would be the equivalent of me being caged in a ten-foot by four-foot space. I might survive but I don’t think I would be too happy about it. In the wild these gorgeous fish are roamers; I would love to know just how far they travel but it has not yet been studied. A Mbu needs a tank they can explore and every time I see Clooney sitting on the bottom at the back of the tank I get a bit sad and feel sorry that I have imprisoned him.

If you truly can accommodate one of these fish and are ready to commit to a pet that could live well over fifteen years, then you will not regret this choice. Clooney has provided me with countless happy moments, and one very scary moment when I thought he was going to die. I have never been so attached nor will I ever be so fond of another pet. When my dog died I was upset, when my rats died I was upset, when the day comes that Clooney will pass on, likely due to my keeping him in a smaller than suitable tank, I shall be distraught. In fact, I find it hard to even type about it; my eyes are actually welling up. If you don’t want to break your heart then get building that big tank please!!

There are plenty of puffers all with great personalities that can be kept in a more reasonable set up, so if you really want a fish with character then go for the puffer you can accommodate. Remember to research them properly as correct information on puffers at local fish stores is scant, to be very kind.