Commercial fishing is reserved to local fishing vessles wholly owned by citizens of Brunei Darussalam or entities wholly owned by them or the government. Foreign investment in aquaculture is permitted without discrimination.
"ANNEX I - SCHEDULE OF BRUNEI DARUSSALAM
Sector: Fisheries and Services Incidental to Fisheries
Obligations Concerned: Performance Requirements (Article 9.10)
Measures: Brunei Darussalam Long-Term Development Plan, Administrative Measures and Guidelines
Description: Investment [...]
Foreign investors may not utilise sites under the control of the Department of Fisheries, Ministry of Primary Resources and Tourism, for any fisheries and services incidental to fisheries activities unless they comply with requirements to purchase, use or accord a preference to goods produced in Brunei Darussalam, or to purchase goods from local suppliers, or to comply with any requirement to transfer technology or other proprietary knowledge, as long as such requirement to transfer technology or other proprietary knowledge does not unreasonably prejudice the legitimate interests of the owner of technology or proprietary knowledge and is not for the purposes of commercial exploitation by Brunei Darussalam.." (ANNEX I - SCHEDULE OF BRUNEI DARUSSALAM, Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP))
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"PART I PRELIMINARY
Interpreation - [...]
"foreign fishing vessel" means any fishing vessel other than a local fishing vessel; [...]
"local fishing vessel" means any fishing vessel which is registered in Brunei Darussalam and which is wholly owned by one or more of the following- (a) a citizen of Brunei Darussalam; (b) a statutory corporation established under the laws of Brunei Darussalam [from definition found in other laws, this refers to SOEs]; (c) the Government; (d) a body corporate or unincorporate established in Brunei Darussalam and wholly owned by any of the persons described in paragraphs (a), (b) or (c), or another body corporate or unincorporate wholly owned by any of the persons described in any of those paragraphs;  
[...]
Operation of fishing vesseL 15. (lJ Any person who operates or allows to be operated any fishing vessel for the purpose of fishing (aJ without a licence; (bJ in contravention of any condition of such a licence; or (cJ in contravention of any direction, is guilty of an offence. 
[...]
PART VII FOREIGN FISHING VESSELS
Fishing etc. using foreign fishing vessels.
17. (1) No foreign fishing vessel shall be used or attempt to be used for fishing or for conducting any research or survey in relation to any fishery, in Brunei Darussalam waters unless (aJ it is authorised to do so under any international fishery agreement between the Government and(i) the government of the country; or (ii) any international organisation, to which such vessel is registered or to which it belongs; and (bJ it is used for those purposes in accordance with a licence. [...]"(Fishery Order, 2009)
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"Interpretation. 
2. In these Regulations, unless the context otherwise requires — 
"fish culture" means any activity involving the maintenance, propagation and promotion of the growth of fish in captivity or upon the sea bed within the territorial waters; 
"fish culture farm" means any establishment or site in which fish culture is carried out and includes all structures and equipment within the establishment or site;
[...]
Licence. 
4. (1) No person shall erect, operate or maintain a fish culture farm unless he has a licence issued under these Regulations.[...]" (FISHERIES (FISH CULTURE FARMS) REGULATIONS, 2002

ANNEX I - SCHEDULE OF BRUNEI DARUSSALAM, Comprehensive and Progressive Agreement for Trans-Pacific Partnership (CPTPP)
Fisheries Order, 2009
FISHERIES (FISH CULTURE FARMS) REGULATIONS, 2002
[<a href="https://www.mfat.govt.nz/assets/Trade-agreements/TPP/Annexes-ENGLISH/Annex-I.-Brunei.pdf">CPTPP</a>],[<a href="http://www.agc.gov.bn/AGC%20Images/LAWS/Gazette_PDF/2009/EN/s025.pdf">Order</a>],[<a href="https://www.agc.gov.bn/AGC%20Images/LAWS/Gazette_PDF/2002/EN/s030.pdf">Reg</a>]