Polycarpa aurata

Difficulty: Meerwasser-Lexikon rates it 'not suitable for aquarium keeping', and Quality Marine notes that sea squirt care is generally considered difficult. Quality Marine nevertheless lists the 'Giant Pacific tunicate' Polycarpa aurata among good candidates, provided you can keep up with feeding.

Acclimation: invertebrates cope very poorly with changes in water chemistry, even minor ones; acclimate it slowly, by floating or drip, without rushing. None of the sources consulted gives a protocol specific to sea squirts.

Placement: attach it to a stable surface, in a well-flushed area as in the wild. Meerwasser-Lexikon mentions zooxanthellae and a need for light, which no other source consulted confirms; light it normally, without treating it as a photosynthetic animal.

Water and filtration: sea squirts tolerate minor drops in water quality; Quality Marine suggests parameters similar to those for mushroom polyps and zoanthids. Because feeding has to be heavy, plan fairly strong filtration, good flow and skimming balanced to remove nutrients and toxins while leaving enough plankton: some sea squirt species secrete toxins.

Tankmates: these attached filter feeders do not bother corals, but avoid aggressive tankmates. Signs to watch: according to That Pet Place it periodically sheds its leathery skin: not necessarily a bad sign. Without enough food it eventually starves. Avoid copper, which harms invertebrates.

According to Quality Marine, food demands are high: direct daily feeding is a must, with brine shrimp nauplii, live rotifers and a splash of mollusc juice. To deliver it, use a baster or syringe, or invert a cut plastic bottle over the colony, squirt the food underneath and remove the bottle after about 5 minutes. That Pet Place advises zooplankton or phytoplankton several times a day: they need an almost constant food supply to avoid starving.