Australian design studio Heliograf has unveiled a plastic-free alternative to the familiar fish-shaped soy sauce packet, offering a compostable option for takeaway sushi and other casual dining.
Developed with Vert Design, the new packaging – called Holy Carp! – is made from bagasse pulp, a fibrous by-product of sugar production. It is designed to replace the single-use plastic soy sauce fish that are widely used but rarely recycled due to their small size.
Like its plastic predecessor, Holy Carp! works as a dropper. Diners squeeze the fish’s belly to release small amounts of soy sauce, keeping the eating experience unchanged for consumers.
The project builds on Heliograf’s earlier Light Soy lamp, a large-scale version of the soy sauce fish made from recycled ocean-bound plastic. That lamp was created to draw attention to the environmental impact of the tiny packets, which often end up in landfills or the ocean, where they can be mistaken for food by birds and marine life.
“We created our recycled ocean-bound plastic lamps to highlight the big problem with the small, seemingly insignificant single-use soy fish and make a difference,” said Heliograf co-founder Angus Ware. “The lamps fund plastic clean-ups and hopefully inspire change in the way we design and use everyday objects, but we always felt we could do more.”
Ware said the studio wanted to move beyond awareness and offer a practical solution. “We have wanted to not just talk about and foreground the problem, but actually offer a real solution to single-use plastic soy sauce ‘fish’ and sachets.”
To do that, Heliograf approached Vert Design, which also worked on the Light Soy lamp and its plant-based packaging. The two studios adapted paper-pulp food container techniques to create a fish-shaped form that is both functional and compostable.
The bagasse-pulp fish has a slightly domed belly that allows it to function as a dropper when squeezed. Its tail fin acts as a grip for opening, while a flanged edge helps create a leak-proof seal. A small hole beneath the fish’s eye dispenses the sauce and can be sealed with a compostable sticker to prevent spills.
Unlike plastic soy sauce fish, which are typically pre-filled in factories, Holy Carp! is designed to be filled fresh by restaurants and used shortly after. Heliograf and Vert Design say the packaging maintains its integrity for up to 48 hours once filled.
The packaging has a capacity of 12 ml and combines bagasse fibres with a food-safe wax, removing the need for internal plastic or PFAS-based linings. Under normal home composting conditions, the material is expected to break down within four to six weeks.
Vert Design said the goal was not to erase the cultural memory of the soy sauce fish, but to preserve it in a more sustainable form.
The original plastic packaging, first developed in Japan in the 1950s to replace glass and ceramic bottles, has since been phased out or banned in some regions, including South Australia.
“From an Australian perspective, discarding such a playful and familiar piece of packaging would be a loss,” said Vert Design founder Andrew Simpson.
“The aim was to create a sustainable alternative that preserves the essence of this familiar experience while honouring its traditional roots.”
