Since most fish are forward propelling creatures, not many people think about fish swimming backwards. But, believe it or not, many of fish absolutely can. Now, they won’t do this often or for any length of time. However, there are situations they experience where it might be necessary.
Save for a few breeds, most fish can and do perform an amazing backstroke that takes keepers by surprise. It usually happens when fish are evading a predator, fighting with other fish or because they’re sick. In general, though, it’s not good for any fish to swim backwards even if they can.
#1. Which fish cannot swim backwards?
There are very few fish that can’t swim backwards. The most famous of these is the shark, but there are others too. The main reason behind their lack of ability is due to biological design.
Sharks can’t swim backwards because of how their skeletons are cartilaginous combined with the fact that their pectoral fins can’t curve upward. Their gills and scales, along with its overall build, limit rearward movement.
If you see a shark backup, it’s most often due to stopping from forward momentum. It’s simply physics coming into play. Because the muscles relax along with forward motion against the water current, they will appear to go back a little bit. Also, they use gravity to sink back somewhat, but they aren’t swimming backwards.
Debates around Other Fish
There are debates on whether other types of fish can swim backwards or not. No one has seen or recorded certain large fish like marlin, arowana and tuna swimming in reverse. Plus, fish that have a vertical pattern of travel, like shrimp fish, seahorses and razorfish don’t swim backwards simply because of their natural direction of propulsion.
#2. Which fish can only swim backwards?
There are no fishes that can only swim backwards. However, there are a few species of fish that do swim rearwards quite well. According to the Journal of the Royal Society, the inclusion of certain fins, like anal and dorsal ones, give them the ability to do this with great ease.
Eels are the most famous for being able to swim backwards as well as it does forwards. They’re adept at this because they can undulate the fin on their bellies. This elongated fin allows them to send electrical discharges to potential prey, thereby stunning them. Then, they back up and lunge forward to grab it.
According to New Scientist magazine, almost all fish that are able to send electrical discharges to their prey have great skill swimming backwards.
The triggerfish has an amazing capability to swim backwards; the Seattle Aquarium says that they’re quite the fancy dancers. Although they don’t perform their backstroke for any length of time, when they do, it’s beautiful to witness. This is due to how their top and bottom fins make them more maneuverable than many other fish.
Black Ghost Knife Fish
Also, the black ghost knife fish swims backwards as a predatory component. They use the fin on their belly to scan for potential prey and swim backwards in order to lunge at it without needing to circle around.
Blue Gill Sunfish
In a study published in Zoology magazine in 2016, the blue gill sunfish has an excellent capacity for reverse-direction propulsion. They employ their pectoral, anal, caudal and dorsal fins to achieve this. The dorsal and anal fins provide a sort of jet propulsion to move in reverse while the pectoral and caudal fins stiffen up for precision.
#3. Will pulling a fish backwards kill it?
Because the design of a fish’s gills, pulling it in a reverse direction can kill it. The gills must operate in a forward direction . This is what allows them to acquire the proper amount of oxygen. If you pull a fish backwards, it will cause suffocation and death.
#4. Can fish swim backwards for long periods of time?
Aside from eels, any amount of backwards swimming by any fish will be very brief. They’ll pull backwards to either catch potential food or to hide from an oncoming predator. Since the design of most gills lend themselves to forward motion, swimming backwards for too long will cause suffocation.
#5. Can clownfish swim backwards?
Clownfish can swim backwards. It’s not often that it happens and it usually takes fish keepers by surprise when they see it. But they will sometimes move in a rearwards direction. Clownfish often do this to back off from a fight with other aquatic life living in the tank.
However, if the backwards movement accompanies other strange behaviors like floating belly up or on the side, it could be an indication of illness. So, it is imperative that aquarists keep an eye on their clownfish to see if they observe any signs of disease.
#6. Can goldfish swim backwards?
Yes, goldfish can swim backwards. They use their pectoral fins in order to achieve a successful backstroke. They won’t do it often or for very long. And, if they do move in a reverse way, it’s a little clumsy and not nearly as graceful as when they swim forward.
That said, if the goldfish swims backwards more often than is normal, they could be ill in some way. Hobbyists should ensure the goldfish isn’t experiencing swim bladder issues.
#7. Can betta fish swim backwards?
Yes, betta fish can definitely swim backwards. They often do this in combat situations, so they can maneuver and back off from their opponent to gain a better advantage point.
But, they could also be experiencing some kind of disease. Swim bladder issues, tank water quality or a severe injury can cause a betta to swim backwards more than usual.
Read Also: Why Fish Swim In Circles?
As you can see, fish very much have the ability to swim in a backwards direction. It’s usually not for very long, but they do have this capacity. Save for sharks, marlins and a few other breeds, almost all fish will swim backwards at least once in their lives.
You must also monitor them closely and handle any issues that arise immediately. In the event they backup often because they’re fighting with other fish in the tank, you have to remove the aggressive fish to keep the tank’s peace.
This is because backwards swimming can be harmful to fish. Since the gills come equipped for forward movement, going backwards can cause them to suffocate. When fish don’t get appropriate amounts of oxygen, it will cause them to struggle.
So that’s it! I hope now you have understood about can fish swim backwards. Please share this article if you found it helpful. Thanks!
Hi! I’m Praveen Ghoshal, the founder of eFishkeeping.com. Inspired by my Dad, I got interested in fishkeeping when I was a kid. Since then, I have been involved with this hobby. Currently, I have 3 fish tanks at our home, where I enjoy this hobby with my Mom, Dad, and Younger Sister. Read more about me here.