What a legal restriction on a species actually means

Possession, sale, import and release are regulated by different provisions and frequently have different answers for the same animal in the same country. A US federal injurious-wildlife listing bans import and interstate transport while leaving existing possession alone. An EU Union list entry has a sell-through period. A permitted-list jurisdiction like Australia treats absence from the list as the prohibition.

That last point inverts an assumption most readers carry. In the EU, a species not being on the invasive-alien-species list means it is not restricted by that instrument. In Australia, a species not being on the live-import list means it cannot be imported. The same fact — 'it is not on the list' — means opposite things.

Japan is the clearest illustration AquariumHQ holds. Its Invasive Alien Species Act designates crayfish at family level: Astacidae, Cambaridae, Cambaroididae and Parastacidae in their entirety, from November 2020. Every ornamental crayfish in this catalogue is inside that — the two-centimetre Mexican dwarf crayfish, the New Guinea Cherax species, the marbled crayfish. A keeping permit exists for academic research, exhibition and education, and the Ministry states directly that keeping one as a pet is not among the purposes for which it can be granted.

The exception is the red swamp crayfish: the most abundantly invasive crayfish in Japan and the one you ARE allowed to keep. In June 2023 it and the red-eared slider were moved into a new category created for them, in which selling, importing and releasing remain prohibited and keeping does not. The reason is stated plainly in the Ministry's own material: both species are already established nationwide and kept in enormous numbers, and a prohibition on keeping would have produced a mass release event on the day it commenced.

So one jurisdiction prohibits the pet-keeping of a tiny crayfish that has never established there and permits the pet-keeping of the crayfish that has colonised the entire country. Both decisions are defensible and neither follows from how invasive the animal is.

A restriction can be drawn at species, genus or family level, and readers — and databases — reliably assume species.

The England and Wales crayfish order prohibits keeping any live crayfish without a ministerial licence, at family level across Astacidae, Cambaridae and Parastacidae, with two narrow exceptions. The dwarf Mexican crayfish sold openly in British aquarium shops is a cambarid and is squarely inside it, which surprises a great many aquarists because the legislation is popularly associated with the signal crayfish.

The EU restriction on apple snails is a genus-level PLANT HEALTH measure rather than an invasive-species listing, directed at Pomacea because the snails damage aquatic plants. AquariumHQ published the wrong law for that finding for several sprints before checking it. The conclusion survived; the account of which instrument does it did not.

Every AquariumHQ entry that found no restriction says so in the form 'no restriction was identified in the sources checked, as of this date'. That is a statement about our search, not about the law, and the two are not interchangeable.

The model also records how far each check actually went. There is a real difference between an editor who opened the current consolidated text of a regulation and confirmed a species appears on its annex, and an editor who recorded that a named instrument exists and what it does in general terms. Both are useful; only the first supports a confident statement about a particular species, and the distinction is rendered next to every entry.

Law goes out of date silently. A legal record with no expiry becomes wrong without anybody touching it, so each entry carries a recheck interval matched to how volatile its instrument is — a statute standing since 1996 is not checked at the cadence of a Union list amended four times in nine years.

Treat everything here as a pointer to the right law rather than as advice about your situation. Then check with the authority named in the entry before acting, particularly if you are moving an animal between countries, and particularly for crayfish, snakeheads, crayfish-adjacent crustaceans and anything on a plant-health list.

And note that the one rule which is not jurisdictional is the one most likely to be an offence where you are: releasing a non-native animal into the wild.