Keeping an aquarium at home can be a rewarding adventure, but not all freshwater fish are safe, or legal, to own.
Some species are prohibited due to their potential to become invasive, harm native wildlife, or pose risks to local ecosystems. If you’re considering a unique freshwater pet, it’s essential to know which species to avoid.
This article is based on online sources for general information only. Regulations vary by country or region. Always verify local rules regarding pet fish.
1. Electric Eels
Contrary to their name, electric eels aren’t actually eels at all, but belong to the knifefish order. These Amazonian natives can generate up to 600 volts of electricity, enough to stun an adult human.
Regulators worldwide have banned them from home aquariums for obvious safety reasons. Beyond the shock risk, they require specialized care including enormous tanks exceeding 1,000 gallons and precise water parameters. Their ability to breathe air also makes them escape artists.
2. Piranhas And Pirambebas
Hollywood has cemented piranhas as ferocious killers, though their reputation exceeds reality. Nevertheless, these South American natives with distinctive jaw structures and razor-sharp teeth are banned in numerous regions.
Wildlife officials fear released specimens could establish breeding populations in warmer climates. California, Florida, and many other states maintain strict prohibitions. Even in areas where ownership isn’t explicitly forbidden, finding a legal seller proves nearly impossible due to transportation restrictions.
3. Snakeheads
Nicknamed “Frankenfish” for their monstrous abilities, snakeheads can survive out of water for days and even wiggle across land to find new habitats. Native to Asia and Africa, these predators have become ecological nightmares when released.
The U.S. banned all snakehead species in 2002 after established populations devastated native ecosystems. They possess primitive lungs allowing air breathing, making them nearly impossible to eradicate once established. Their voracious appetite and rapid reproduction make them particularly destructive invaders.
4. Tilapias
While tilapia appears on restaurant menus worldwide, many species are banned from home aquariums. These hardy cichlids reproduce with astonishing efficiency: a single female can produce hundreds of offspring monthly.
Florida and other warm regions prohibit tilapia ownership without special permits. When released, they quickly establish breeding populations that outcompete native fish for food and habitat. Their adaptability to poor water conditions makes them especially successful invaders in disturbed ecosystems. Some species can even survive in brackish environments.
5. Crucian Carp
Crucian carp have earned their place on banned species lists worldwide. These European natives resemble goldfish but possess extraordinary survival skills, including the ability to survive in nearly frozen water and oxygen-depleted environments.
When released, they hybridize with native fish, threatening genetic purity of local species. Their incredible adaptability allows them to thrive where other fish perish. The Lacey Act prohibits their transport across state lines in the U.S., effectively banning them from the aquarium trade.
6. European Perch
With their striking tiger-striped patterns and vibrant red fins, European perch might seem like attractive aquarium candidates. Unfortunately, their beauty masks their potential for ecological harm.
These adaptable predators can survive in various water conditions and reproduce rapidly. Australia learned this lesson the hard way when introduced perch decimated native fish populations.
Most U.S. states prohibit their possession, as do many other countries worldwide. Their competitive nature and voracious appetite make them particularly threatening to smaller native species.
7. Silver Arowana
Known as the “water monkey” for their remarkable jumping abilities, silver arowanas captivate aquarists with their prehistoric appearance and intelligence. Yet these Amazonian giants are restricted in many regions.
Growing up to 4 feet long, they quickly outgrow standard aquariums.
Their protected status under CITES regulations limits international trade. Australia has completely banned them due to their potential impact if released. Even in areas where they’re legal, proper care requires specialized knowledge and enormous tanks exceeding 1,000 gallons.
