Marbled Lungfish (Protopterus aethiopicus)

Also known as the Leopard Lungfish, the marbled lungfish is a species of lobe-finned fish found throughout Northeast Africa. Like other lungfish the marbled lungfish can breath air using a special lung like appendage. Using their ‘lungs’ these fish can live in streams and swamps that are dry for long periods of time, emerging when the water returns. Marbled lungfish usually inhabit rivers, swamps and floodplains where they feed on molluscs, fish and insects. The marbled lungfish is also one of the few animals that have had their genome’s sequenced it also has one of the largest genomes of all vertebrates at an outstanding 133 billion base pairs long!



Image Source(s)


So I recently had the opportunity to purchase a West African Lungfish (Protopterus annectens). These are ancient sarcopterygians that grow very large and are pretty unique animals. They possess many traits that early tetrapods had and many odd characteristics for fish such as a four chambered heart and primitive lung structures. These are traits more commonly found in amphibians (some of the first tetrapods) rather than most fish.

After talking it over with my SO, whom obviously has a say in whether or not we could house this fish as an adult, we came to the conclusion that we can make the space for him if he ends up growing 3ft+. With lungfish living 20 years, and quite often more in captivity, they are definitely a long term commitment. In fact there is a Queensland lungfish at the Shedd Aquarium in Chicago that has been in their collection since 1933. (That’s 81 years!) Visually lungfish look so reminiscent of a salamander or axolotl, it’s hard to believe they’re a fish at all. There are only six extant species of lungfish with the largest species reaching over 6ft in length.

Almost all lungfish species are wild caught so I want to give this little guy a nice environment that allows him to behave as he would naturally. Right now I have him set up in a 20gal with some sand and plants while he adjusts. He is already roughly 6-7in in length so he’ll need to go into a 29 gal or 40b as soon as he settles in and I’m certain he’s healthy. He was a rather unexpected purchase and so I have to hunt down a stand for the bigger tank since I used to keep them on a large dresser which I no longer own.

Behaviorally hes a pretty sedentary critter except for when food is around or when he goes up for air. The rest of the time is spent napping among the plants, under the driftwood, or sifting through sand for food he may have missed. I also didn’t have a net large enough to for him but I was pleasantly surprised to find he doesn’t mind being handled gently. Right now he’s being fed NLS large fish formula 3mm sinking pellets and frozen bloodworms. Once I’ve had him for a while I’ll likely write a caresheet on P. annectens. I’m open to name suggestions as well!


Coelacanth (SEE-lah-kanth) it is closely related to the aquatic ancestors of land-living tetrapods. This endangered animal was believed to have gone extinct at the time of the dinosaurs, until the first scientifically noted rediscovery in 1938!!! also is called the living fossil

Because coelacanths (Latimeria chalumnae) are endangered, scientists can only examine dead specimens that fishermen accidentally catch in trawls. These rare animals show internal fertilization and bear live young (something very rare in bony fishes, but their reproductive behaviour is poorly known. Pregnant females are especially rare: one fish was caught near Mozambique in 1991, and another near Zanzibar in 2009.

Recently (in 2013) researchers concluded that coelacanth are monogamous, Through  genetic paternity tests on the 49 total offspring of two preserved pregnant coelacanths. Researchers showed that each coelacanth chose only one male to sire her brood.

This behavior poses a risk to coelacanths in part because of the onerous three-year-long pregnancies in females. The babies are fully developed when they’re born, but the mother sacrifices a lot of energy and is more vulnerable to predators while she carries her young. If one male with a bad set of genes sires the brood, all the offspring can suffer—and those three years might be wasted. They suggests monogamy in coelacanths could arise because females cannot physically store sperm from multiple males. However, monogamy is rare in the animal kingdom.


What It Means to Be a Fish

The word “fish” is a very touchy subject for biologists.  It actually has zero scientific meaning today, and is an archaic word that is well past its expiration date only because the general public keep using it and scientists have to use it to make any sense to the general public (“reptile” and “amphibian” both also have that problem, by the way).  I could go on a long, passionate rant about how horrible and ucky the word “fish” is, but I will spare humanity this time.

There is actually a scientific meaning for “fish,” but it isn’t what you may expect.  “Fish” is now synonymous with “vertebrate,” which means that a fish is basically any animal with a backbone (in biology we are trying to stamp out defining life via physical traits, but I won’t go into the technical stuff).  This means that you are a fish.  Birds are one of the most common types of fish on Earth.  There are herds of fish roaming the African savannah.  To argue that this isn’t true–that these animals are not fish–is to argue that it is completely logical for a branch growing on the left side of a tree to suddenly switch to growing from the right side of the tree.  It is the exact same argument.

But when I say that I am a “fish” (horrible word), don’t be fooled.  I am not saying that I am something like a tuna, and nor are you (unless you are a tuna reading this).  It is true that both humans and tuna are “fish,” but I am not descended from anything like a tuna, nor a salmon, nor a sturgeon.  Usually when we think of the word “fish,” we think of one of those animals–they are a type of creature known as actinopterygians (we also call them “ray-finned fish”).  They are fish (as in, vertebrates) that have fins right up against their torsos.  Most of them actually evolved after the dinosaurs.

Humans are not ray-finned fish.  We are “lobe-finned fish."  Throw out any idea you may have of what a "fish” is like, and allow me to describe what your typical lobe-finned fish looks like.  Most lobe-finned fish have beaks.  They have very complicated respiratory systems that can extract a lot of oxygen from the air.  They have feathers, and can fly.  What’s that, you say?  It sounds like I’m describing a bird?  I am–by far, the most common lobe-finned fish on our planet are birds.  When you picture the average lobe-finned fish, you should be picturing them.  The next most common type of lobe-finned fish has hair and feeds its children with nutrient-rich sweat–mammals.  Frogs, salamanders, lizards, turtles, snakes, and crocodiles are all lobe-finned fish too.  Several lobe-finned fish swim in the water–most of them we call “whales,” “dolphins,” or “seals.”

Lobe-finned fish used to be the dominant group of aquatic animals, well before sharks, rays, and most ray-finned fish evolved (although their ancestors were certainly around back then, trying to swim away from a ferocious lobe-finned fish’s open jaws).  They have since lost the marine throne to the ray-finned fish, although lobe-finned fish such as orcas remain at the top of the aquatic food chain.  There are only two lobe-finned fish alive today that look anything like the lobe-finned fish back in their aquatic hayday before the dinosaurs.  They are the coelacanth and the lungfish.  How are they like you?  Just like you, the coelacanth and lungfish do not have fins pressed tightly up against their bodies.  Although they do not have fingers and toes, coelacanths and lungfish have arms, legs, hands, and feet just like you do (these limbs are the “lobes” that we get the name “lobe-finned fish” from).  Just like you, a coelacanth or lungfish has a humerus, a radius and ulna, and carpal and metacarpal bones; just like you, a coelacanth or lungfish has a femur, a tibia and fibula, and tarsal and metatarsal bones.  Lungfish, like most lobe-finned fish today, can even breathe air.

Now, certainly, ray-finned fish and lobe-finned fish have a common ancestor.  But the ray-finned fish (what you typically think of when you think “fish”) are our cousins, not our siblings or ancestors.  We are fish, yes; we are even bony fish (sharks, rays, ratfish, lampreys, and hagfish are not).  But we are not anything like a tuna, nor were we ever anything like a tuna.  The problem with saying that humans are “fish” is that people hear that and think “ray-finned fish” instead of thinking “lobe-finned fish” and then are incredulous that anybody could say we are one and the same.  The word “fish” in general needs to be deleted from our vocabulary, but until the general public catch on that it is meaningless and misleading, scientists will have to continue to use it when speaking to the general public.

^ The above picture is a picture I took from Wikipedia of a lungfish.  Notice how the fins of the lungfish are at the tips of arms and legs–these are lobe-finned fish.