The Different Types of Porcellio Isopods
Porcellio is the genus of large, flat, fast isopods - the ones that can't roll into a ball. It contains roughly 130-150 described species, and the ones in the UK hobby range from the bulletproof beginner favourites to some of the biggest and most sought-after isopods you can keep. The key thing to understand is that the genus splits into three fairly clear tiers: the hardy laevis and scaber morphs anyone can keep, a middle group of striking Mediterranean species, and the Spanish giants that need proper ventilation and patience. Browse the full range in our Porcellio collection.
What Defines the Genus
- They don't conglobate. Porcellio can't roll into a ball. They're flat-bodied and rely on speed instead - which also means they're more active and more visible than most isopods.
- They're big. Many species exceed 20 mm, and the Spanish giants go considerably further.
- They're surface-active. You actually see them, unlike burrowing species that spend their lives hidden.
- They're mostly Mediterranean and southern European in origin, with a few North African species and one very familiar UK native.
- They're protein-hungry. More so than other genera - and that matters, because underfed Porcellio are the source of most reports of isopod "aggression".
Beginner Tier
Dairy Cow (Porcellio laevis)
The best beginner Porcellio there is, and one of the best beginner isopods full stop. Bold black-and-white spotting, 20-25 mm, easy at 20-24°C with a humidity gradient, and a reliable breeder that produces visible offspring within months.
The one thing to remember: they're seriously protein-hungry, so give them a weekly protein feed. Our Dairy Cow care guide covers it, and you can browse Dairy Cow Isopods here.
Snow White (Porcellio laevis)
The white morph of the same species - identical hardy genetics in a cleaner visual package. Same size, same care, same forgiving nature.
One correction worth making: Snow Whites are Mediterranean and European in origin, not South American, despite that being repeated across the hobby. Browse our Snow White Isopods.
Lava (Porcellio scaber morph)
A selectively bred morph of the common rough woodlouse - the same species you'll find under a log in a British garden, but with striking orange-red lava patterning. Hardy, adaptable, and a good way into the genus. Browse our Lava Isopods.
Intermediate Tier
These want a little more care - better ventilation, more attention to the moisture gradient - but none is difficult:
- Porcellio werneri - Greek species with distinctive markings and moderate care needs.
- Bolivari Lemonade - a bright yellow morph of a Spanish species.
- Haasi High Yellow - high-contrast Spanish species, striking in a planted setup.
- Baeticensis Violet - unusual purple tones, a genuine collector's animal.
- Ornatus High Yellow - bold yellow banding.
- Spatulatus "Coros" - a less common Spanish species for keepers building a broad collection.
The Spanish Giants
These are the reason a lot of keepers get into Porcellio at all. They're the largest isopods in the hobby - considerably bigger than anything native to Britain - and they're genuinely impressive animals.
- Porcellio magnificus - the giant of the genus, and the one most people want.
- Porcellio hoffmannseggii - huge, and surprisingly manageable for its size.
- Porcellio expansus - broad-bodied and striking.
- Giant Orange - large and vividly coloured.
They want better drainage than tropical species, more ventilation, and a calcium-rich substrate. They're also slower breeders, so treat them as a project rather than a quick colony. And feed them well - big Porcellio with insufficient protein are exactly where moulting cannibalism comes from.
Frequently Asked Questions
What are Porcellio isopods?
A genus of around 130-150 species of large, flat, fast-moving isopods. Unlike Armadillidium they can't roll into a ball, so they rely on speed instead - which makes them noticeably more active and visible in an enclosure. Most hobby species are Mediterranean or southern European in origin.
Can Porcellio isopods roll into a ball?
No. They're flat-bodied and can't conglobate. If you want the classic pill-bug rolling behaviour, you want Armadillidium instead.
What is the best Porcellio for a beginner?
Dairy Cow (Porcellio laevis). Hardy, prolific, large enough to see easily, and forgiving of mistakes. Snow White is the same species in a different colour, and equally beginner-friendly.
What is the biggest Porcellio isopod?
The Spanish giants - P. magnificus, P. hoffmannseggii and P. expansus. They're the largest isopods commonly kept in the hobby and considerably bigger than any UK native species.
Do Porcellio need more protein than other isopods?
Yes, noticeably. It's the single most important thing to get right with the genus. Underfed Porcellio are behind almost every report of isopod aggression or moulting cannibalism - offer fish flakes or dried shrimp once or twice a week and the problem doesn't arise.
Are Porcellio isopods good for bioactive setups?
Excellent - they're vigorous processors of waste. But be cautious pairing large Porcellio with small or delicate animals; for sensitive setups, Dwarf Whites are the safer cleanup crew.
Browse the full genus in our Porcellio collection above, or see the wider range in our isopods collection.
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