A tank of crayfish in the classroom is a normal sight in Japanese primary schools. It appears in the Life Environment Studies curriculum and again in science. On 1 June 2023 the red swamp crayfish became a designated invasive alien species. Does that mean schools can no longer keep them? Reading the statute and the ministry notices, it turns out a school is treated differently from a household.
The short answer first.
- Keeping red swamp crayfish and red-eared sliders at school is not illegal. No permit and no notification are needed
- But a school is not a household. It falls under keeping "as a business", so it must follow the keeping standard set by ministerial notice. The conditions are stricter than for a household
- Catching them on a class trip and bringing them back is allowed. Once an animal has been brought back, it cannot be returned to a pond or river
- Handing animals the school keeps to pupils to take home counts as distribution and is restricted. Handing them out and collecting them within the same lesson is allowed
- Releasing one into the wild carries up to three years' imprisonment or a fine of up to ¥3 million (both may be imposed; up to ¥100 million for a corporation)
- Buying them, even for educational use, requires a permit
- The American bullfrog is not in the conditional category. Keeping one at all requires a permit
- MEXT circulated a notice to every prefectural board of education on 22 May 2023
The rest of this article traces each point back to the source.
This article organises what the statute and public documents say. Whether a particular case falls under the rules is for the authorities to decide. Provisions and notices are quoted from the versions I checked on 14 August 2026. Translations of Japanese legal text are my own and are given for orientation, not as official renderings.
1. What changed on 1 June 2023
The red swamp crayfish (Procambarus clarkii) and the red-eared slider (Trachemys scripta) became designated invasive alien species on 1 June 2023. Not through an ordinary designation, though: they were placed in a category called Conditionally Designated Invasive Alien Species. The Cabinet decision was taken on 20 January 2023.
The category rests on Article 5 of the Supplementary Provisions of the Invasive Alien Species Act, added by the 2022 amendment. The provision allows the government, by Cabinet Order, to disapply all or part of Articles 4 and 7 to 9 for a species where applying them in full would itself risk making the damage worse.
Designate a widely kept animal outright and a great many of them lose their homes at once, which pushes them into the wild. The category exists to avoid that. What was actually disapplied is Article 4 (ban on keeping) and part of Article 8 (ban on transfer).
Two prohibitions were left standing. Article 7 (ban on import) and Article 9 (ban on release) remain fully in force. "Conditional" does not mean the regime is light. It means two of the four prohibitions have been partly lifted.
The Ministry of the Environment sets out what an ordinary person may and may not do. Catching them, taking them home and keeping them are not restricted. Giving one away to a small number of people, free of charge, needs no procedure. Selling, distributing or buying live individuals is prohibited, and so is releasing them.
The ministry is also explicit about catch and release:
Catching one and releasing it on the spot straight away (catch and release) is not subject to the restrictions.
Ministry of the Environment, "Regulations and procedures for red-eared sliders and red swamp crayfish" (my translation)Releasing on the spot is fine; releasing after taking it home is prohibited. That line is where school activities sit.
2. A school is not a household
The exemption is written separately for those who keep the animals as a business and for everyone else. The Ministry of the Environment gives examples of the first group:
Keeping outside an ordinary household, whether for profit or not, on a repeated and continuous basis, to a degree that can socially be regarded as the conduct of an undertaking.
(Examples) Keeping at a zoo or aquarium / keeping at a crayfish fishing pond / keeping as part of an educational undertaking at a school or similar / keeping at a research facility for academic research / keeping as part of a control programme
Schools are named. Whether money is involved makes no difference, as the text says.
For this group one extra condition attaches. The Supplementary Provisions of the Cabinet Order disapply Article 4 only where the keeping follows "the method prescribed by the competent minister for each species". That method is Ministry of the Environment Notice No. 36 of 2023, promulgated on 17 April 2023 and applied from 1 June, the day the Cabinet Order took effect.
The ministry's summary lists three requirements:
- keep the animals in a facility meeting the detailed criteria for a designated keeping facility
- check the state of the animals and inspect the facility on a regular basis
- keeping outside the facility is prohibited in principle, with an exception where several handlers are present and escape is prevented, for example by using a net of sufficient strength
No permit is required. No notification either. What does fall outside the conditions is a lidless tank left standing in a corridor. A school is not being given easier treatment. It has conditions attached that a household does not.
The detailed facility criteria are in a separate ministry PDF. I have not verified those figures. Anyone actually setting up a tank would do well to read the criteria directly.
3. Bringing one back is a one-way trip
On 22 May 2023 MEXT issued a circular titled "Handling of red-eared sliders and red swamp crayfish at schools" to prefectural and designated-city boards of education. Attached to it in full is a request issued by the Ministry of the Environment four days earlier. The environment ministry's text is the one that goes into classroom practice.
Since catching is not subject to the Invasive Alien Species Act, catching wild red-eared sliders and the like during school educational activities is possible. Taking the animals caught back with you is also possible; however, as releasing into the wild an animal once taken back is prohibited, please ensure that they are taken back only after careful consideration of whether the animal can be kept to the end without being let go.
Ministry of the Environment, Alien Species Office, request of 18 May 2023, attached to the MEXT circular (my translation)The curriculum documents say nothing about what happens after collection. The only line in the primary science commentary is about the collecting itself:
In keeping and cultivation activities, where organisms are collected outdoors, collection shall be kept to the minimum necessary and consideration given to maintaining the ecosystem, while fostering an attitude of caring for living things through recognising the delicacy of their structure and function.
MEXT, Commentary on the Course of Study for Primary Schools (2017), Science, Chapter 4 (my translation)"Observe it, then put it back where you found it" is a familiar way to close a lesson. For these two species, putting it back after taking it home is prohibited. Creatures that may be returned and creatures that may not are mixed together in the same ditch.
4. Sending one home with a pupil counts as distribution
The same request contains the line closest to daily practice:
Handing red-eared sliders and the like to pupils during school educational activities and using them for dissection and so on, or collecting them back, on the spot is possible; however, handing red-eared sliders and the like kept by the school to pupils to take home constitutes distribution and is therefore subject to the restrictions.
Ministry of the Environment, Alien Species Office, request of 18 May 2023 (my translation)It is restricted even though nothing is charged, because of how the exemption is drafted. The Supplementary Provisions disapply Article 8 for "transfers that do not amount to sale, purchase or distribution". Passing one to a friend falls inside that. Handing them out to a whole class to take home falls on the distribution side.
Letting families take the surplus when the tank gets crowded; sending the tank home with one family over the summer. Both look ordinary. The first sits on the distribution side of the line.
| Situation at school | How the Act treats it |
|---|---|
| Catching crayfish in a nearby ditch during a lesson | Not restricted |
| Catching one and releasing it on the spot | Not restricted |
| Bringing them back and keeping them in class | Allowed, subject to the keeping standard |
| Releasing them in a local pond at the end of the year | Prohibited (Article 9, release) |
| Handing kept animals to pupils to take home | Distribution; restricted |
| Handing them out and collecting them within the lesson | Allowed |
| Buying them for educational use | Permit required |
| They live in the school biotope and nobody tends them | Not keeping |
| The same biotope, but staff feed them | Keeping |
The last two rows come from the same request. Even where the animals live in a school biotope of their own accord, this is not keeping so long as no specific act of management is carried out — feeding, attracting them, maintaining them, preventing injury. Start putting food in and the classification changes.
The penalty for release is not a light one. A breach of Article 9 falls under Article 32: up to three years' imprisonment or a fine of up to ¥3 million, and both may be imposed together. For a corporation there is a separate ceiling of ¥100 million.
5. The bullfrog is not in the conditional category
Only two species are conditionally designated. Other familiar animals around a school sit in the ordinary category. The American bullfrog has been listed since the Act took effect on 1 June 2005.
Under an ordinary designation Article 4 applies in full. Keeping, cultivating, holding and transporting are all prohibited in principle, and keeping one requires the minister's permit. Carrying one home counts as transport.
Education, though, is among the permitted purposes:
Article 3. The purposes prescribed by ministerial ordinance under Article 5, paragraph 1 of the Act shall be the following.
(i) exhibition at a museum, zoo or similar facility
(ii) education
(iii) maintenance of a livelihood
(the remainder omitted)
A school is in a position to obtain a permit: prepare a facility the animal cannot escape from, apply to the ministry's regional office and go through the review. Meanwhile, the provision listing the "unavoidable circumstances" under which keeping is allowed without a permit mentions neither schools nor educational institutions. So far as I could check, there is no provision that removes the requirement because the keeper is a school.
Crayfish split three ways
Similar names, different treatment:
| Species | Treatment | Since |
|---|---|---|
| Japanese crayfish (Cambaroides japonicus) | Not regulated under the Act | — |
| Red swamp crayfish | Conditionally designated | 1 June 2023 |
| All other non-native crayfish (yabby, marron, signal crayfish and so on) | Designated; a permit is needed to keep one | 2 November 2020 |
The ministry puts it plainly: "since 2 November 2020 all non-native crayfish other than the red swamp crayfish have been designated as invasive alien species." The blue crayfish sold in pet shops can fall in that group.
Other species a class might meet on a nature walk are listed too: the cane toad, the brown tree frog Polypedates leucomystax, western mosquitofish, bluegill, largemouth and smallmouth bass, channel catfish, all gars, the pale-blue tiger butterfly Hestina assimilis, the red-necked longhorn beetle, the buff-tailed bumblebee, the Argentine ant, the yellow-legged hornet and the Chinese mitten crab. On 14 August 2026 the ministry's list showed 162 designated species and species groups.
6. Compulsory keeping, and one line of commentary
In Life Environment Studies, keeping animals is set out as a continuous activity running across two school years:
Content (7) of Section 2 shall be dealt with across the two school years, and continuous keeping and cultivation shall be carried out so that the relationship with animals and plants deepens.
Course of Study for Primary Schools (2017), Life Environment Studies, Section 3 (3) (my translation)Invasive species appear once, in the commentary, positioned alongside weekend care, working with vets, handwashing and allergies:
Furthermore, sufficient consideration must be given to the handling of invasive alien species and the like, so as not to lead to the destruction of the local natural environment or ecosystem.
MEXT, Commentary on the Course of Study for Primary Schools (2017), Life Environment Studies (my translation)The instruction to address invasive species directly appears in lower secondary science, where the section on nature and humankind says to "touch on climate change and invasive alien species". At primary level, keeping animals is compulsory and the invasive-species point is one line of commentary.
The phrase used for choosing which animals to keep is "those living in the familiar environment". One of the easiest creatures to find in a familiar Japanese waterway is the red swamp crayfish. The two overlap here.
The Ministry of the Environment writes about the same overlap in its control manual, listing it among the routes by which the species spreads:
Within the school curriculum of observing, collecting and keeping familiar organisms, red swamp crayfish are sometimes kept and eventually released on school grounds or into nearby waters.
Ministry of the Environment, "Manual on measures for the red swamp crayfish", April 2022 (my translation)The same manual notes releases made "as an act of goodwill, under the misconception that spreading familiar aquatic creatures to places where they do not live is a good thing". It points at the seam in the system rather than at anyone's conduct.
7. The material already exists
On 14 April 2022 the Ministry of the Environment published classroom material on the red swamp crayfish: two sets for Life Environment Studies in years 1 and 2, two for science in years 3 and 4, and a guide for teachers.
The teachers' guide states what the material is built around:
In a lesson dealing with living things, the single most important point to convey is that a creature you keep is kept responsibly to the end of its life (lifelong keeping) — and this applies to any creature, not only invasive ones.
Ministry of the Environment, "For teachers — aims, outline and classroom use of this material" (my translation)The same guide adds that "the red swamp crayfish itself is not to blame; behind the problem lies selfish human conduct". The three principles of preventing damage from invasive species close the document: do not introduce, do not abandon, do not spread.
For the red-eared slider there is a separate teaching programme, aimed at upper primary years and up, built as two 45-minute periods.
All of this sits on the environment ministry's site. It is not linked from the MEXT page that collects teaching materials. On the notice side there is the circular of 22 May 2023, and the following year's "Keeping animals at school (request)" of 28 August 2024, where consideration based on that circular appears as a single line under "other matters".
That 2024 notice also touches on what pupils bring in:
Not only in cases where animals are kept under the ownership or possession of the school, but also where insects and the like are kept under the ownership or possession of individual pupils, appropriate guidance shall in either case be provided, in line with the Course of Study, so that pupils may develop familiarity with living things and a wish to care for them.
MEXT, "Keeping animals at school (request)", 28 August 2024 (my translation)That passage is written from the angle of guidance and of costs falling on families, not from the angle of invasive species. On pupils bringing in creatures they caught themselves, I could not find a public document setting out whether it is allowed or how it should be handled.
Closing
The red swamp crayfish has not become impossible to keep. What changed is the way out. Catching one and carrying it back is as it was; the road back has closed. For a school, conditions from a ministerial notice attach to the keeping itself.
Both of those are settled before the tank goes on the shelf. How many to bring back, whether they can be kept to the end, what happens when they breed. The ministry's own request asks for the thinking to happen in that order.
What is written here is one way of looking at it. Statutes and notices get amended, and local ordinances may set their own rules. If you notice something, I would be glad to hear it through the contact form.
Sources
- Act on the Prevention of Adverse Ecological Impacts Caused by Designated Invasive Alien Species (Act No. 78 of 2004), Articles 1, 4, 5, 7, 8, 9, 9-2, 32, 33, 36 and Supplementary Provision Article 5 e-Gov (Japanese)
- Enforcement Order (Cabinet Order No. 169 of 2005), Appended Table 1 and Supplementary Provision Article 2 e-Gov (Japanese)
- Enforcement Regulation (MAFF/MOE Ordinance No. 2 of 2005), Articles 2 and 3 e-Gov (Japanese)
- Ministry of the Environment, "Regulation of conditionally designated invasive alien species" page / "Regulations and procedures" page
- Ministry of the Environment press release, 20 January 2023 (Cabinet decision) page
- Ministry of the Environment press release, 17 April 2023 (facility criteria and keeping method) page / summary PDF / outline of the regulation PDF
- Ministry of the Environment, "Non-native crayfish" page / "List of designated species" page
- Ministry of the Environment, "Procedures for keeping" page / "Penalties" page
- MEXT circular, 22 May 2023, "Handling of red-eared sliders and red swamp crayfish at schools" (includes the Ministry of the Environment request of 18 May 2023 as Attachment 1) PDF
- MEXT notice, 28 August 2024, "Keeping animals at school (request)" PDF / index page
- MEXT, Commentary on the Course of Study for Primary Schools (2017), Life Environment Studies PDF / Science PDF / Lower Secondary Science PDF
- Ministry of the Environment press release, 14 April 2022 (crayfish materials) page / "Learning tools" page / "For teachers" PDF
- Ministry of the Environment, "Manual on measures for the red swamp crayfish", April 2022 PDF / "Let's learn about the red-eared slider" material 1 PDF