Porcellio Haasi 'High Yellow' Isopods

There is nothing subtle about a mature Haasi High Yellow. This is a Spanish giant among the largest Porcellio kept in the hobby, and the High Yellow line pushes its colour to a vivid, bright yellow across most of the body, offset by darker shading on the sides and legs. Add the long, distinctive tail appendages the males carry and you have a genuine display animal, visible clear across a room. Every colony we send is captive-bred here in the UK.

Introduction

This is Porcellio haasi 'High Yellow', a line selected over generations for intense yellow from a species native to the calcareous mountain rock of north-eastern Spain, around Aragón. Standard P. haasi show only subtle yellow; the High Yellow is the deliberately-bred bright form. It ranks with the largest Spanish giants alongside the Titan, and stands apart on colour within the genus.

Appearance

A large Porcellio: males reach around 20 mm in the body, with long uropods, the paired "tails" at the rear, adding another 10 mm or so on top. Those long tails are the easiest way to sex a colony, since males carry them far longer than females. The yellow is bold rather than an accent, with the darker sides giving it depth, and it firms up as animals mature. Like all Porcellio it does not conglobate, relying on speed rather than rolling into a ball.

Care

Two things matter most. First, moisture: the old "dry-loving Spanish species" line is only half right. Their calcareous-rock home holds damp crevices, so they want a clear gradient, roughly a quarter damp and the rest drier, not a uniformly arid tub, which is slowly fatal, especially to the young. Pair that with genuinely high ventilation, since stagnant humid air is more dangerous than slightly low humidity. Second, space: males are territorial and will chase rivals, so give a starter group real room, 15 litres and up, with several separated hides so they can hold their own corners. Build a drier substrate of topsoil and flake soil with sand for drainage and plenty of limestone through it, because a calcareous-rock animal has a high calcium demand, and keep rotting white wood available, which is their preferred food. Our guide to the different types of Porcellio puts it in context.

Diet

Haasi are protein-hungry giants: a constant base of dried hardwood leaf litter and rotting white wood, vegetable once or twice a week, and protein two or three times a week, since underfed Porcellio will turn on each other. Keep several calcium sources going at all times, and set fresh food on the dry side so it does not spoil. A springtail culture helps around the damp zone.

Breeding

Haasi are seasonal breeders, prolific through spring and summer and quieter in the cooler months, so colony growth comes in bursts rather than a steady trickle, mirroring their Spanish climate. Give them space to keep male aggression low, a proper moisture gradient, constant calcium and protein, and a gentle seasonal swing in temperature, and a settled colony produces substantial broods in its peak months. Patience through the quiet season is part of keeping them.

Who is this for?

The Haasi High Yellow suits the keeper with a little Porcellio experience who wants something big and genuinely colourful, and the collector of Spanish giants, next to the Titan and the yellow-marked P. ornatus or the flat Greek Shield. It is not a beginner's isopod, nor one for a cramped or bone-dry setup; start on a hardier species like the Scaber Mix if you are new to the genus.

All stock is captive-bred here in the UK and ships under our live arrival guarantee, in a ventilated deli tub with a damp sphagnum corner inside a double-walled box. We post Monday to Thursday by Royal Mail next day before 1pm, with a 20% overcount included. Setup components are in our accessories range.