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5 popular Freshwater Sharks

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A short guide to Freshwater sharks.

Freshwater Sharks

Freshwater sharks attract many aquarists, mostly for their spectacular looks that do in many ways resemble a true seagoing shark.  These guys though are not actual sharks and most of them are more closely related to Carp.   There are a few species of freshwater shark available within the aquarium trade, so we’re going to cover a few of the most common here.  Many of these fish are referred to also as ‘Shark minnow’s’, this is a species group and is logged under the family Cyprinidae/Cyprinid.

Freshwater sharks make a great addition to many aquariums.  They look great and most are quite active.  They do require some level of knowledge to look after properly though.  I have seen a few incidents recently that are only going to end in disaster, so hopefully, we can help to avoid future mishaps with the aid of one short article.


Red tail Shark

The Red tail shark is a striking little fish.  It has the strong dorsal fin, streamlined torpedo body, and the head shape of a shark.  These guys stay quite small though so are suited to a smaller enclosure (your tank).  They grow to 5 inches plus and have a black/coal coloured body with a vibrant red tail.  At 5 inches in length, these guys are quite happy in the home aquarium, but it does need to be a larger aquarium.

Red tail sharks are territorial creatures and will set up an area that they deem ‘just for me’ in your aquarium.  Just about anything that enters this area will be quickly chased away and attacked if it doesn’t get out quick enough.  They are particularly aggressive towards conspecifics (other red tail sharks) and any other bottom dweller that may look like them.

Due to this territorial behaviour, they do need more space than the average 5-inch fish would.  This will allow them to select a territory with a hideout and allow your other fish to remain out of the way when they need to.

Red tail sharks are omnivorous and will eat algae, they will eat fish food, and if they feel like it, they may eat the scales from your other fish.  This can cause infection and ultimately death of the target fish, so if you have a Red tail shark, keep an eye on it.

Despite this, Red tail sharks are suitable for a community tank.  They just need to be well-fed, have enough space and ideally not be housed with another Red tail shark or anything that looks like one.

Due to their territorial aggression, it’s almost impossible to breed them in the home aquarium.  Breeding requires more space than the average home aquarium can provide, with each fish needing its own square metre or so to prevent them from fighting over space.


Red Tail Shark



Rainbow Shark

The Rainbow shark is very similar in appearance to the red tail shark.  However, the main difference is that the red tail shark only has a red tail.  The Rainbow shark has red colouring in its tail, dorsal, anal and caudal fins too.  There is also an albino variety which has a bright white body and sometimes red eyes.

Rainbow shark diet and behaviour is also very similar to that of the red tail.  They can be aggressive towards any other fish that enters their space and will be particularly aggressive to other Rainbow sharks, or anything that is similar.

This is another is that if cared for properly is suited to a community tank, but again you will need to keep an eye on it.  They do not get on with anything that looks like them, such as a red tail shark, or anything that inhabits the same space.  So, any other bottom dwellers need to be chosen carefully or avoided, I have owned a Rainbow shark in the past and it would even fight with a Pictus catfish if the cat dared to enter the Rainbow sharks cave.

Breeding is a similar story too, it is very unlikely that they will breed in a home aquarium and should be kept as single fish, unless in a very large aquarium.  Sexing is quite difficult, Males of both red fin and Rainbow sharks tend to have more pointed fins and females have a rounder belly.  This is more obvious once a female is carrying eggs as she will become even rounder.  The albino variety may turn greenish if it is a female carrying eggs.  The eggs inside her can give her a green tint.


Rainbow Shark



Silver Shark / Bala Shark

Bala sharks are extremely common and well known in the aquarium trade.  They have the shark like torpedo body, strong dorsal fin and beautiful black colouring in their fins which stands out due to their shining silver body.

Bala sharks are extremely popular, but they are not for all aquariums, these are a schooling fish which means they are best kept in groups of at least 6, but they grow to 35cm in length and are fast swimmers.

As you can guess, a group of 6 35cm fast swimming Bala sharks require a large amount of space.  Many online recommendations say 150 gallons / 560 litres, but i think that is a little small for 6 of these guys.

The Bala shark, despite its size is a gentle giant.  They are very placid and are well suited to a community aquarium.  Like most fish, they will eat a tiny fish if able to, so try not to keep them with anything they could easily swallow.  They come from fast flowing rivers in the wild so strong filtration is a must to provide a current for them to swim in.

Bala sharks are omnivorous so will eat a wide range of food from plants to live foods.  Due to their large size they do need a good amount of protein in their diet so a good quality pellet food is the best as their staple, but they will appreciate some variety.

Bala sharks will breed in the home aquarium, but they do need a lot of space to do so.  Sexing them can be tricky as there is very little sexual dimorphism, Males tend to be slightly larger when fully grown and females tend to have rounder bellies.


Bala Shark



Black Shark

The black shark is actually fairly rare but they are seen occasionally.  The black shark is like the larger cousin of the Red tail or Rainbow shark, these are definitely less common but do look similar, the main differences being colour and size.  The black shark can grow to a whopping 35 inches long, so it is not a small fish and needs a very large aquarium.  To add to that, it is, like its smaller cousins, very territorial and can be aggressive.

Care of these fish is essentially the same as the red tail or rainbow shark but scaled up to 35 inches.  There are very few home aquariums that are capable of housing a fish of this size.


Black Shark



Pangasius/Iridescent shark

These guys are commonly labelled as sharks, but they are not, they are catfish.  Iridescent sharks are related to the Giant Mekong Catfish, which is one of the largest freshwater fish in the world.  They are not related to the other sharks covered in this article and they do look quite different.  As their name would suggest, they are shiny and appear iridescent (glowing), they have a long sleek body and strongly pointed fins, their eyes almost appear to pop out of the side of their heads, a bit like a hammerhead shark.

Iridescent sharks are regularly up for sale in aquarium shops at a size of 2 – 3 inches, but these are extremely large fish that can grow to a meter upwards, they are also schooling fish as juveniles, so really they shouldn’t be in home aquariums.

These giants are actually fairly peaceful for their size, but they are predatory and will eat anything they can swallow.  Their ability to swallow such large prey is pretty impressive and they can swallow fish that are almost as large as they are.

Due to their size, they are quite messy fish, so as well as a humongous tank, they will need plenty of filtration to keep it clean.  A single adult iridescent shark will require at least 300 gallons / 1363 litres as an absolute minimum, so a suitable aquarium for a group of these would be more like a public display.

Iridescent sharks eat a wide variety of food, as juveniles they like a meaty diet as this enables them to grow.  But they will eat plants too, so if you add any plants to their aquarium, be prepared for the plants to disappear.


Pangasius Shark Catfish



Keeping Freshwater sharks in your aquarium can be very rewarding.  They often have a great personality, just ensure you do some research, make sure they will fit in your tank, and choose tank mates wisely.  For more info on Freshwater sharks, have a look here.  If you have a shark and are concerned about aquarium size, check out our article here.


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About the author

James @Seriously Fishy

I am a fish keeping enthusiast with over 20 years experience. I currently keep American Cichlids (CA) which are my favourite fish to keep so far. I started Seriously Fishy as I noticed a large volume of people on various web pages looking for help with Aquarium basics. I created the first Seriously Fishy book to solve the issue in 28 pages, that led to the Seriously Fishy UK fish forum and blog.

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