There's a video doing the rounds. The scene is dark and murky — the deep ocean. In the footage a huge isopod is feeding on a carcass when a shark swims into shot, properly drawn by the smell of the same meal. As the shark gets close, the isopod grabs hold and clings on as the shark tries to leave. Is it defending its meal? Hoping the shark itself becomes the next course? We genuinely don't know enough about these deep-sea creatures to answer with confidence.
The viral framing tends to be that the isopod "attacks" the shark, but that's properly misleading. Bathynomus are deep-sea scavengers, not predators. The famous videos show opportunistic feeding behaviour — clinging on, sometimes pulling pieces away, sometimes scavenging from shark feeding aggregations. Impressive footage, but not the hunter-prey dynamic the headlines suggest.
It's also not 100% clear which Giant Isopod species appears in these videos — they're all Bathynomus sp. but the genus is properly more diverse than was understood even a few years ago. Bathynomus giganteus was long considered the largest, but recent species descriptions (including B. jamesi from the South China Sea, described in 2022) have complicated the picture. The deep ocean still hides species we haven't formally documented.
Can You Keep One at Home?
It might surprise you to know that it's properly possible to keep Giant Isopods in aquariums — though not your average fish tank. Several public aquariums around the world have successfully kept them. The challenges are significant.
The most famous example is Toba Aquarium in Japan. In 2014, one of their males died after roughly a five-year fast — the specimen had arrived in 2007 and stopped eating in 2009. The death attracted properly international attention because deep-sea scavengers like Bathynomus have astonishingly slow metabolisms. Long intervals between meals aren't unusual for the genus; they've evolved to handle exactly that scenario, since meals on the deep ocean floor (the carcasses of whales, sharks, and other large animals that sink down) are unpredictable and infrequent.
The size, by the way, is genuinely impressive but more "small dog" than the giant beasts the media sometimes portray. Adults of the larger species reach 30-50 cm — substantial, but not the metre-long monsters of internet myth.
The practical problems with keeping one at home:
- Tank size: Few of us have space for an aquarium that would house an adult Bathynomus properly
- Temperature: They need to be kept dark and very cold — around 4 °C, matching the deep-sea environment they evolved in. This means running something colder than your fridge, in the open, in the middle of your living room
- Power costs: You'd either need to live in eternal cold, or have an electricity bill that rivals a small village
- Lifespan: They're genuinely long-lived; this is a multi-decade commitment
For the vast majority of UK keepers, properly keeping a Bathynomus at home isn't realistic.
The Land-Based Alternative: Large Porcellio Species
The good news is that the UK invertebrate hobby has properly excellent large isopod options — terrestrial species that scratch the "impressive size" itch without needing deep-sea cooling systems.
Porcellio expansus 'La Senia'
This is properly one of the larger terrestrial isopods commonly kept. Adults reach around 4-5 cm — no, not the 40 cm of Bathynomus, but a properly manageable size that still has substantial body presence in an enclosure. They prefer warmer temperatures than 4 °C, and like to live in leaf litter rather than the ocean depths.
This means you can keep them in a properly manageable enclosure — something that can sit on a shelf or desk as a display case. They can show territorial behaviour toward each other, so you don't need to start with a massive colony, but they do appreciate space to spread out and establish their own zones within the enclosure.
Porcellio expansus Orange
If you're new to keeping isopods, the Orange variant is properly another wonderful choice. P. expansus Orange is more versatile than many premium isopods, able to live in a wider range of temperatures and humidities — as shown by their wide native range across Spain and Portugal. Adults reach around 3.5 cm, so they're properly smaller than the La Senia variant but not by much.
The wider tolerance makes them properly more forgiving for beginners learning isopod husbandry. They handle moderate husbandry variation better than premium Cubaris or Ardentiella species.
Porcellio hoffmannseggii
Sitting between the two P. expansus variants comes another properly substantial Spanish Porcellio species. P. hoffmannseggii reaches around 4 cm and thrives in a drier environment than most other isopods — properly suited to keepers who prefer the lower-humidity husbandry approach.
Like other Porcellio species, mature individuals can show territorial behaviour with each other, particularly mature males. Plan enclosure size to give them space to spread out rather than crowding them.
Where Do These Isopods Come From?
The animals you'll receive from us come from our own captive-bred stock. That means they haven't travelled too far to get to you — they've been bred here in England under UK conditions, which makes them properly well-adapted to UK home environments. For each species's native range and detailed care information, check out the individual product listings.
For the broader Porcellio collection, browse our Porcellio collection. For other large isopod options, the Porcellio magnificus is another substantial Spanish species worth considering — at around 4-5cm adult length, it's properly in the same size class as the P. expansus variants but with different visual character.
Setting Up for Large Porcellio Species
The setup requirements for these large terrestrial alternatives are properly straightforward. They're much more forgiving than tropical Cubaris or Ardentiella species:
- Enclosure size: Larger than for smaller species — 10-20 litres minimum for a small colony of 5-10 animals. Larger if you can
- Substrate: Organic topsoil mixed with leaf litter and decaying hardwood
- Hides: Plenty of cork bark pieces — they appreciate vertical cover as well as horizontal hides
- Calcium: Cuttlebone always available
- Temperature: UK ambient room temperature is properly fine; no specialist heating required
- Humidity: Moderate, with a moisture gradient (one end damper than the other) — they're not tropical species and don't need constantly high humidity
Browse our full accessories collection for setup essentials.
Giant Isopods at Home: The Honest Verdict
While the idea of keeping a deep-sea scavenger at home may seem amazing, it's probably not a great idea in the long run. The combination of tank size, cooling requirements, lifespan commitment, and the genuine welfare considerations of keeping a deep-sea species in shallow conditions makes it a project for properly specialised public aquariums, not home hobbyists.
The land-based alternatives, though, offer most of the visual appeal — substantial body size, impressive presence, and the satisfaction of keeping properly large isopods — without any of the deep-sea complications.
Plus, while a single Bathynomus could potentially eat a shark (with patience and the right circumstances), the Porcellio expansus Orange above could also eat a shark — as long as you cut it up into very small pieces, fed it to them gradually over several years, and were prepared to be properly patient. But they'd give it a go.
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