If you’re a fish enthusiast or have spent time as an aquarium hobbyist, you may have heard of the Red-tail shark. These freshwater fish are known for their shark-like black bodies contrasted by bright red tails.
But are Red-tail sharks actually sharks? Many people wonder whether this is just a marketing ploy or if there’s some truth to it.
In this article, we aim to explore that question. Join us as we dive deep into the differences between Red-tail sharks and the common sharks that we know.
To put it simply, no, Red-tail sharks aren’t actual sharks. Red-tail sharks, or Redtail sharkminnows, are freshwater fish endemic to Thailand that are part of the Cyprinidae family.
That classification makes them more closely related to carps, minnows, and barbs than actual sharks in the Selachimorpha superorder.
Despite resembling sharks in appearance, they lack many of the characteristics and morphology that make actual marine sharks unique.
Okay, saying they’re not sharks because they don’t fit the scientific classification doesn’t really explain much, does it?
As such, we enumerated the critical morphological and behavioral distinction between actual sharks and Red-tail sharks for you. These are the following:
One of the most significant differences between sharks and Red-tail sharks is their bone composition.
Every shark in order Selachimorpha has cartilaginous skeletons. That means their bones comprise the same flexible tissue in your nose and ears.
It doesn’t matter where they live, whether in freshwater (like the Borneo River shark), salt water (like the great white shark), or in between (like the bull shark).
Compared to Red-tail sharks with bony skeletons, their bodies are more flexible. As a result, they swim faster with less energy.
The gill slits of Red-tail sharks also differ from marine sharks.
Like the average fish, Red-tail sharks only have two gill slits, one on each side. Sharks, on the other hand, have five to seven gill slits on each side.
The fin structure of sharks is also distinct from that of Red-tail sharks. The first thing you’d notice with shark fins is that they’re more fleshy and broader than other fish.
Additionally, Red-tail sharks have pectoral fins fused to their head like most bony fish, which is a feature sharks don’t possess.
Lastly, most shark species have two dorsal fins; Red-tail sharks generally have one.
Ironically though, Red-tail sharks got their name because of how their dorsal fin looks.
Although sharks are generally considered large animals, the sizes of different shark species vary greatly.
The average size of Red-tail sharks is six inches, but they can grow up to eight. The only actual sharks that come close to them are the smallest ones, like the dwarf lantern shark or pygmy shark.
Real sharks commonly have triangular serrated teeth that grab on their prey. They’re also notorious for having a large number of teeth, with multiple rows that continuously replace old ones.
Compared to real sharks, the Red-tail shark’s tooth is lackluster. They have small flat teeth designed to grind and crush plant matter and small crustaceans.
There’s also variability between the diets of sharks and Red-tail sharks. Red-tail sharks have an omnivorous diet that leans towards plants, while most sharks are carnivorous.
Although some sharks are omnivores, like the whale sharks, they’re the exception, not the rule.
Sharks in order Selachimorpha are primarily found in saltwater, but some species are flexible and can survive in rivers and seas, like the bull shark.
On the other hand, you can only find the Red-tail shark in rivers and streams in Thailand, and they’re strictly freshwater fish.
While we mostly view sharks as lone hunters, many of their species live in social environments with their kind.
In contrast, Red-tail sharks are considerably more solitary. When put in an aquarium, they’re observed to chase away and bully other fish.
As such, fish keepers tend to give them spacious tanks.
So, are Red-tail sharks actually sharks? From the difference between their bones to the contrast in their behavior, we can safely say that they’re rather far from each other.
Nevertheless, Red-tail sharks are still great as pets. Don’t let the misnomer deter you from keeping them.
With their black bodies and bright red tails, Red-tail sharks will stand out from other fish and would make a great addition to your aquarium, shark or not.
Jeff has always enjoyed having pets, but as a child, he was drawn to his family’s fish tank. Being able to maintain a small ecosystem and observe the behaviors and interactions in the underwater world peaked his interest early on and has kept him hooked until this day. On Avid Aquarist, Jeff shares everything he’s learned about helping aquatic life survive and thrive in a home aquarium.